WorldWideScience

Sample records for sound waves reverberating

  1. New theory on the reverberation of rooms. [considering sound wave travel time

    Science.gov (United States)

    Pujolle, J.

    1974-01-01

    The inadequacy of the various theories which have been proposed for finding the reverberation time of rooms can be explained by an attempt to examine what might occur at a listening point when image sources of determined acoustic power are added to the actual source. The number and locations of the image sources are stipulated. The intensity of sound at the listening point can be calculated by means of approximations whose conditions for validity are given. This leads to the proposal of a new expression for the reverberation time, yielding results which fall between those obtained through use of the Eyring and Millington formulae; these results are made to depend on the shape of the room by means of a new definition of the mean free path.

  2. Ensemble statistics of active and reactive sound intensity in reverberation rooms

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Molares, Alfonso Rodrıguez

    2011-01-01

    This paper examines fundamental statistical properties of the active and reactive sound intensity in reverberant enclosures driven with pure tones. The existing theory for sound intensity in a diffuse sound field, which is based on Waterhouse’s random wave model and therefore limited to the region...

  3. Effect of direction on loudness for wideband and reverberant sounds

    DEFF Research Database (Denmark)

    Sivonen, Ville Pekka; Ellermeier, Wolfgang

    2006-01-01

    The effect of incidence angle on loudness was investigated for wideband and reverberant sounds. In an adaptive procedure, five listeners matched the loudness of a sound coming from five incidence angles in the horizontal plane to that of the same sound with frontal incidence. The stimuli were...... presented to the listeners via individual binaural synthesis. The results confirm that loudness depends on sound incidence angle, as it does for narrow-band, anechoic sounds. The directional effects, however, were attenuated with the wideband and reverberant stimuli used in the present investigation....

  4. Decay of reverberant sound in a spherical enclosure

    International Nuclear Information System (INIS)

    Carroll, M.M.; Chien, C.F.

    1977-01-01

    The assumption of diffuse reflection (Lambert's Law) leads to integral equations for the wall intensity in a reverberant sound field in the steady state and during decay. The latter equation, in the special case of a spherical enclosure with uniformly absorbent walls and uniform wall intensity, allows exponential decay with a decay time which agrees closely with the Norris--Eyring prediction. The sound-intensity and sound-energy density in the medium, during decay, are also calculated

  5. Human Sound Externalization in Reverberant Environments

    DEFF Research Database (Denmark)

    Catic, Jasmina

    In everyday environments, listeners perceive sound sources as externalized. In listening conditions where the spatial cues that are relevant for externalization are not represented correctly, such as when listening through headphones or hearing aids, a degraded perception of externalization may...... occur. In this thesis, the spatial cues that arise from a combined effect of filtering due to the head, torso, and pinna and the acoustic environment were analysed and the impact of such cues for the perception of externalization in different frequency regions was investigated. Distant sound sources...... were simulated via headphones using individualized binaural room impulse responses (BRIRs). An investigation of the influence of spectral content of a sound source on externalization showed that effective externalization cues are present across the entire frequency range. The fluctuation of interaural...

  6. Reverberation impairs brainstem temporal representations of voiced vowel sounds: challenging periodicity-tagged segregation of competing speech in rooms

    Directory of Open Access Journals (Sweden)

    Mark eSayles

    2015-01-01

    Full Text Available The auditory system typically processes information from concurrently active sound sources (e.g., two voices speaking at once, in the presence of multiple delayed, attenuated and distorted sound-wave reflections (reverberation. Brainstem circuits help segregate these complex acoustic mixtures into auditory objects. Psychophysical studies demonstrate a strong interaction between reverberation and fundamental-frequency (F0 modulation, leading to impaired segregation of competing vowels when segregation is on the basis of F0 differences. Neurophysiological studies of complex-sound segregation have concentrated on sounds with steady F0s, in anechoic environments. However, F0 modulation and reverberation are quasi-ubiquitous.We examine the ability of 129 single units in the ventral cochlear nucleus of the anesthetized guinea pig to segregate the concurrent synthetic vowel sounds /a/ and /i/, based on temporal discharge patterns under closed-field conditions. We address the effects of added real-room reverberation, F0 modulation, and the interaction of these two factors, on brainstem neural segregation of voiced speech sounds. A firing-rate representation of single-vowels’ spectral envelopes is robust to the combination of F0 modulation and reverberation: local firing-rate maxima and minima across the tonotopic array code vowel-formant structure. However, single-vowel F0-related periodicity information in shuffled inter-spike interval distributions is significantly degraded in the combined presence of reverberation and F0 modulation. Hence, segregation of double-vowels’ spectral energy into two streams (corresponding to the two vowels, on the basis of temporal discharge patterns, is impaired by reverberation; specifically when F0 is modulated. All unit types (primary-like, chopper, onset are similarly affected. These results offer neurophysiological insights to perceptual organization of complex acoustic scenes under realistically challenging

  7. Rainforests as concert halls for birds: Are reverberations improving sound transmission of long song elements?

    DEFF Research Database (Denmark)

    Nemeth, Erwin; Dabelsteen, Torben; Pedersen, Simon Boel

    2006-01-01

    that longer sounds are less attenuated. The results indicate that higher sound pressure level is caused by superimposing reflections. It is suggested that this beneficial effect of reverberations explains interspecific birdsong differences in element length. Transmission paths with stronger reverberations......In forests reverberations have probably detrimental and beneficial effects on avian communication. They constrain signal discrimination by masking fast repetitive sounds and they improve signal detection by elongating sounds. This ambivalence of reflections for animal signals in forests is similar...... to the influence of reverberations on speech or music in indoor sound transmission. Since comparisons of sound fields of forests and concert halls have demonstrated that reflections can contribute in both environments a considerable part to the energy of a received sound, it is here assumed that reverberations...

  8. Sound localization and word discrimination in reverberant environment in children with developmental dyslexia

    Directory of Open Access Journals (Sweden)

    Wendy Castro-Camacho

    2015-04-01

    Full Text Available Objective Compare if localization of sounds and words discrimination in reverberant environment is different between children with dyslexia and controls. Method We studied 30 children with dyslexia and 30 controls. Sound and word localization and discrimination was studied in five angles from left to right auditory fields (-90o, -45o, 0o, +45o, +90o, under reverberant and no-reverberant conditions; correct answers were compared. Results Spatial location of words in no-reverberant test was deficient in children with dyslexia at 0º and +90o. Spatial location for reverberant test was altered in children with dyslexia at all angles, except –-90o. Word discrimination in no-reverberant test in children with dyslexia had a poor performance at left angles. In reverberant test, children with dyslexia exhibited deficiencies at -45o, -90o, and +45o angles. Conclusion Children with dyslexia could had problems when have to locate sound, and discriminate words in extreme locations of the horizontal plane in classrooms with reverberation.

  9. Plaatsafhankelijkheid van timbre bij nagalm (Place dependence of timbre in reverberant sound fields)

    NARCIS (Netherlands)

    Plomp, R.; Steeneken, H.J.M.

    1973-01-01

    The sound-pressure level of a simple tone in a diffuse sound field varies from point to point with a theoretical standard deviation of 5.57 dB. This variability affects the timbre of complex tones in reverberant sound fields, Experiments have shown that the timbre dissimilarity at any two positions

  10. Sound wave transmission (image)

    Science.gov (United States)

    When sounds waves reach the ear, they are translated into nerve impulses. These impulses then travel to the brain where they are interpreted by the brain as sound. The hearing mechanisms within the inner ear, can ...

  11. Acoustic parameters of sound insulating materials investigation in small reverberation rooms on rubber plates

    Directory of Open Access Journals (Sweden)

    О.О. Козлітін

    2005-01-01

    Full Text Available  The new method of sound insulating materials acoustic characteristics investigation in small reverberation rooms was elaborated. The research of sound insulating materials on rubber plates was done. The analysis of obtained results of acoustic parameters of materials being a part of the composite real structures of airplane was carried out.

  12. Digital servo control of random sound test excitation. [in reverberant acoustic chamber

    Science.gov (United States)

    Nakich, R. B. (Inventor)

    1974-01-01

    A digital servocontrol system for random noise excitation of a test object in a reverberant acoustic chamber employs a plurality of sensors spaced in the sound field to produce signals in separate channels which are decorrelated and averaged. The average signal is divided into a plurality of adjacent frequency bands cyclically sampled by a time division multiplex system, converted into digital form, and compared to a predetermined spectrum value stored in digital form. The results of the comparisons are used to control a time-shared up-down counter to develop gain control signals for the respective frequency bands in the spectrum of random sound energy picked up by the microphones.

  13. Sound insulation and reverberation time for classrooms - Criteria in regulations and classification schemes in the Nordic countries

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2016-01-01

    Acoustic regulations or guidelines for schools exist in all five Nordic countries. The acoustic criteria depend on room uses and deal with airborne and impact sound insulation, reverberation time, sound absorption, traffic noise, service equipment noise and other acoustic performance...... have become more extensive and stricter during the last two decades. The paper focuses on comparison of sound insulation and reverberation time criteria for classrooms in regulations and classification schemes in the Nordic countries. Limit values and changes over time will be discussed as well as how...... not identical. The national criteria for quality level C correspond to the national regulations or recommendations for new-build. The quality levels A and B are intended to define better acoustic performance than C, and D lower performance. Typically, acoustic regulations and classification criteria for schools...

  14. A wavenumber approach to quantifying the isotropy of the sound field in reverberant spaces

    DEFF Research Database (Denmark)

    Nolan, Melanie; Fernandez Grande, Efren; Brunskog, Jonas

    2018-01-01

    This study proposes an experimental method for evaluating isotropy in enclosures, based on an analysis of the wavenumber spectrum in the spherical harmonics domain. The wavenumber spectrum, which results from expanding an arbitrary sound field into a plane-wave basis, is used to characterize the ...

  15. Topography Estimation of the Core Mantle Boundary with ScS Reverberations and Diffraction Waves

    Science.gov (United States)

    Hein, B. E.; Nakata, N.

    2017-12-01

    In this study, we use the propagation of global seismic waves to study the Core Mantle Boundary (CMB). We focus on the use of S-wave reflections at the CMB (ScS reverberations) and outer-core diffracted waves. It is difficult imaging the CMB with the ScS wave because the complexity of the structure in the near surface ( 50 km); the complex structure degrades the signal-to-noise ratio of of the ScS. To avoid estimating the structure in the crust, we rely on the concept of seismic interferometry to extract wave propagation through mantle, but not through the crust. Our approach is compute the deconvolution between the ScS (and its reverberation) and direct S waves generated by intermediate to deep earthquakes (>50 km depth). Through this deconvolution, we have the ability to filter out the direct S wave and retrieve the wave field propagating from only the hypocenter to the outer core, but not between the hypocenter to the receiver. After the deconvolution, we can isolate the CMB reflected waves from the complicated wave phenomena because of the near-surface structure. Utilizing intermediate and deep earthquakes is key since we can suppress the near-surface effect from the surface to the hypocenter of the earthquakes. The variation of such waves (e.g., travel-time perturbation and/or wavefield decorrelation) at different receivers and earthquakes provides the information of the topography of the CMB. In order to get a more detailed image of the topography of the CMB we use diffracted seismic waves such as Pdiff , Sdiff, and P'P'. By using two intermediate to deep earthquakes on a great circle path with a station we can extract the wave propagation between the two earthquakes to simplify the waveform, similar to how it is preformed using the ScS wave. We generate more illumination of the CMB by using diffracted waves rather than only using ScS reverberations. The accurate topography of CMB obtained by these deconvolution analyses may provide new insight of the

  16. Small-sized reverberation chamber for the measurement of sound absorption

    International Nuclear Information System (INIS)

    Rey, R. del; Alba, J.; Bertó, L.; Gregori, A.

    2017-01-01

    This paper presents the design, construction, calibration and automation of a reverberation chamber for small samples. A balance has been sought between reducing sample size, to reduce the manufacturing costs of materials, and finding the appropriate volume of the chamber, to obtain reliable values at high and mid frequencies. The small-sized reverberation chamber, that was built, has a volume of 1.12 m3 and allows for the testing of samples of 0.3 m2. By using diffusers, to improve the diffusion degree, and automating measurements, we were able to improve the reliability of the results, thus reducing test errors. Several comparison studies of the measurements of the small-sized reverberation chamber and the standardised reverberation chamber are shown, and a good degree of adjustment can be seen between them, within the range of valid frequencies. This paper presents a small laboratory for comparing samples and making decisions before the manufacturing of larger sizes. [es

  17. Evanescent reverberation

    NARCIS (Netherlands)

    Serra, R.

    2012-01-01

    Abstract—One of the main statistical models for fields in reverberation chambers is the so-called "plane wave integral representation" model of David Hill. However, despite being widely known and used, this model (as stated by D. Hill himself) lacks a rigorous demonstration, especially when

  18. A machine-hearing system exploiting head movements for binaural sound localisation in reverberant conditions

    DEFF Research Database (Denmark)

    May, Tobias; Ma, Ning; Wierstorf, Hagen

    2015-01-01

    This paper is concerned with machine localisation of multiple active speech sources in reverberant environments using two (binaural) microphones. Such conditions typically present a problem for ‘classical’ binaural models. Inspired by the human ability to utilise head movements, the current study...

  19. Sound waves in hadronic matter

    Science.gov (United States)

    Wilk, Grzegorz; Włodarczyk, Zbigniew

    2018-01-01

    We argue that recent high energy CERN LHC experiments on transverse momenta distributions of produced particles provide us new, so far unnoticed and not fully appreciated, information on the underlying production processes. To this end we concentrate on the small (but persistent) log-periodic oscillations decorating the observed pT spectra and visible in the measured ratios R = σdata(pT) / σfit (pT). Because such spectra are described by quasi-power-like formulas characterised by two parameters: the power index n and scale parameter T (usually identified with temperature T), the observed logperiodic behaviour of the ratios R can originate either from suitable modifications of n or T (or both, but such a possibility is not discussed). In the first case n becomes a complex number and this can be related to scale invariance in the system, in the second the scale parameter T exhibits itself log-periodic oscillations which can be interpreted as the presence of some kind of sound waves forming in the collision system during the collision process, the wave number of which has a so-called self similar solution of the second kind. Because the first case was already widely discussed we concentrate on the second one and on its possible experimental consequences.

  20. Problems in nonlinear acoustics: Pulsed finite amplitude sound beams, nonlinear acoustic wave propagation in a liquid layer, nonlinear effects in asymmetric cylindrical sound beams, effects of absorption on the interaction of sound beams, and parametric receiving arrays

    Science.gov (United States)

    Hamilton, Mark F.

    1990-12-01

    This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.

  1. Fundamental plasma emission involving ion sound waves

    International Nuclear Information System (INIS)

    Cairns, I.H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L ± S → T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived. (author)

  2. Influence of impedance phase angle on sound pressures and reverberation times in a rectangular room

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Lee, Doheon; Santurette, Sébastien

    2014-01-01

    , but with an absorptive ceiling are investigated. The zero phase angle, which has commonly been assumed in practice, is regarded as reference and differences in the sound pressure level and early decay time from the reference are quantified. As expected, larger differences in the room acoustic parameters are found...

  3. Sound power emitted by a pure-tone source in a reverberation room

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Molares, Alfonso Rodriguez

    2009-01-01

    Energy considerations are of enormous practical importance in acoustics. In "energy acoustics," sources of noise are described in terms of the sound power they emit, the underlying assumption being that this property is independent of the particular environment where the sources are placed. Howev...

  4. Nonlocal nonlinear coupling of kinetic sound waves

    Directory of Open Access Journals (Sweden)

    O. Lyubchyk

    2014-11-01

    Full Text Available We study three-wave resonant interactions among kinetic-scale oblique sound waves in the low-frequency range below the ion cyclotron frequency. The nonlinear eigenmode equation is derived in the framework of a two-fluid plasma model. Because of dispersive modifications at small wavelengths perpendicular to the background magnetic field, these waves become a decay-type mode. We found two decay channels, one into co-propagating product waves (forward decay, and another into counter-propagating product waves (reverse decay. All wavenumbers in the forward decay are similar and hence this decay is local in wavenumber space. On the contrary, the reverse decay generates waves with wavenumbers that are much larger than in the original pump waves and is therefore intrinsically nonlocal. In general, the reverse decay is significantly faster than the forward one, suggesting a nonlocal spectral transport induced by oblique sound waves. Even with low-amplitude sound waves the nonlinear interaction rate is larger than the collisionless dissipation rate. Possible applications regarding acoustic waves observed in the solar corona, solar wind, and topside ionosphere are briefly discussed.

  5. Long-lasting novelty-induced neuronal reverberation during slow-wave sleep in multiple forebrain areas.

    Directory of Open Access Journals (Sweden)

    Sidarta Ribeiro

    2004-01-01

    Full Text Available The discovery of experience-dependent brain reactivation during both slow-wave (SW and rapid eye-movement (REM sleep led to the notion that the consolidation of recently acquired memory traces requires neural replay during sleep. To date, however, several observations continue to undermine this hypothesis. To address some of these objections, we investigated the effects of a transient novel experience on the long-term evolution of ongoing neuronal activity in the rat forebrain. We observed that spatiotemporal patterns of neuronal ensemble activity originally produced by the tactile exploration of novel objects recurred for up to 48 h in the cerebral cortex, hippocampus, putamen, and thalamus. This novelty-induced recurrence was characterized by low but significant correlations values. Nearly identical results were found for neuronal activity sampled when animals were moving between objects without touching them. In contrast, negligible recurrence was observed for neuronal patterns obtained when animals explored a familiar environment. While the reverberation of past patterns of neuronal activity was strongest during SW sleep, waking was correlated with a decrease of neuronal reverberation. REM sleep showed more variable results across animals. In contrast with data from hippocampal place cells, we found no evidence of time compression or expansion of neuronal reverberation in any of the sampled forebrain areas. Our results indicate that persistent experience-dependent neuronal reverberation is a general property of multiple forebrain structures. It does not consist of an exact replay of previous activity, but instead it defines a mild and consistent bias towards salient neural ensemble firing patterns. These results are compatible with a slow and progressive process of memory consolidation, reflecting novelty-related neuronal ensemble relationships that seem to be context- rather than stimulus-specific. Based on our current and previous results

  6. The ensemble variance of pure-tone measurements in reverberation rooms

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Molares, Alfonso Rodriguez

    2010-01-01

    Reverberation rooms are often used for measuring the sound power emitted by sources of sound. At medium and high frequencies, where the modal overlap is high, a fairly simple model based on sums of waves from random directions having random phase relations gives good predictions of the ensemble s...

  7. Negative ion sound solitary waves revisited

    Science.gov (United States)

    Cairns, R. A.; Cairns

    2013-12-01

    Some years ago, a group including the present author and Padma Shukla showed that a suitable non-thermal electron distribution allows the formation of ion sound solitary waves with either positive or negative density perturbations, whereas with Maxwellian electrons only a positive density perturbation is possible. The present paper discusses the qualitative features of this distribution allowing the negative waves and shared with suitable two-temperature distributions.

  8. Broadcast sound technology

    CERN Document Server

    Talbot-Smith, Michael

    1990-01-01

    Broadcast Sound Technology provides an explanation of the underlying principles of modern audio technology. Organized into 21 chapters, the book first describes the basic sound; behavior of sound waves; aspects of hearing, harming, and charming the ear; room acoustics; reverberation; microphones; phantom power; loudspeakers; basic stereo; and monitoring of audio signal. Subsequent chapters explore the processing of audio signal, sockets, sound desks, and digital audio. Analogue and digital tape recording and reproduction, as well as noise reduction, are also explained.

  9. Transformation of second sound into surface waves in superfluid helium

    International Nuclear Information System (INIS)

    Khalatnikov, I.M.; Kolmakov, G.V.; Pokrovsky, V.L.

    1995-01-01

    The Hamiltonian theory of superfluid liquid with a free boundary is developed. Nonlinear amplitudes of parametric Cherenkov radiation of a surface wave by second sound and the inner decay of second sound waves are found. Threshold amplitudes of second sound waves for these two processes are determined. 4 refs

  10. Estimation methods for sound levels and reverberation time in a room with irregular shape or absorption distribution

    NARCIS (Netherlands)

    Gerretsen, E.

    2006-01-01

    The reverberation time of an enclosed space is an important parameter to describe the acoustic quality in enclosed spaces. Mainly due to its simplicity Sabine’s equation is normally used even though the considered situations seldom comply with its preconditions: regular room shape, regular

  11. Testing Cosmology with Cosmic Sound Waves

    CERN Document Server

    Corasaniti, Pier Stefano

    2008-01-01

    WMAP observations have accurately determined the position of the first two peaks and dips in the CMB temperature power spectrum. These encode information on the ratio of the distance to the last scattering surface to the sound horizon at decoupling. However pre-recombination processes can contaminate this distance information. In order to assess the amplitude of these effects we use the WMAP data and evaluate the relative differences of the CMB peaks and dips multipoles. We find that the position of the first peak is largely displaced with the respect to the expected position of the sound horizon scale at decoupling. In contrast the relative spacings of the higher extrema are statistically consistent with those expected from perfect harmonic oscillations. This provides evidence for a scale dependent phase shift of the CMB oscillations which is caused by gravitational driving forces affecting the propagation of sound waves before recombination. By accounting for these effects we have performed a MCMC likelihoo...

  12. WAVE: Interactive Wave-based Sound Propagation for Virtual Environments.

    Science.gov (United States)

    Mehra, Ravish; Rungta, Atul; Golas, Abhinav; Ming Lin; Manocha, Dinesh

    2015-04-01

    We present an interactive wave-based sound propagation system that generates accurate, realistic sound in virtual environments for dynamic (moving) sources and listeners. We propose a novel algorithm to accurately solve the wave equation for dynamic sources and listeners using a combination of precomputation techniques and GPU-based runtime evaluation. Our system can handle large environments typically used in VR applications, compute spatial sound corresponding to listener's motion (including head tracking) and handle both omnidirectional and directional sources, all at interactive rates. As compared to prior wave-based techniques applied to large scenes with moving sources, we observe significant improvement in runtime memory. The overall sound-propagation and rendering system has been integrated with the Half-Life 2 game engine, Oculus-Rift head-mounted display, and the Xbox game controller to enable users to experience high-quality acoustic effects (e.g., amplification, diffraction low-passing, high-order scattering) and spatial audio, based on their interactions in the VR application. We provide the results of preliminary user evaluations, conducted to study the impact of wave-based acoustic effects and spatial audio on users' navigation performance in virtual environments.

  13. The effect of loudness on the reverberance of music: reverberance prediction using loudness models.

    Science.gov (United States)

    Lee, Doheon; Cabrera, Densil; Martens, William L

    2012-02-01

    This study examines the auditory attribute that describes the perceived amount of reverberation, known as "reverberance." Listening experiments were performed using two signals commonly heard in auditoria: excerpts of orchestral music and western classical singing. Listeners adjusted the decay rate of room impulse responses prior to convolution with these signals, so as to match the reverberance of each stimulus to that of a reference stimulus. The analysis examines the hypothesis that reverberance is related to the loudness decay rate of the underlying room impulse response. This hypothesis is tested using computational models of time varying or dynamic loudness, from which parameters analogous to conventional reverberation parameters (early decay time and reverberation time) are derived. The results show that listening level significantly affects reverberance, and that the loudness-based parameters outperform related conventional parameters. Results support the proposed relationship between reverberance and the computationally predicted loudness decay function of sound in rooms. © 2012 Acoustical Society of America

  14. Decay curves in coupled, reverberant spaces

    DEFF Research Database (Denmark)

    Balin, Jamilla; Nolan, Melanie; Fernandez Grande, Efren

    2016-01-01

    This study investigates the effect of panel and boundary diffusers in a reverberant space. Diffusers are usually mounted in a reverberation chamber to increase the diffuse sound field as recommended in Annex A of ISO 354. The ISO is not specific about the location or the material of the panels; t...

  15. Viscosity and attenuation of sound wave in high density deuterium

    International Nuclear Information System (INIS)

    Inoue, Kazuko; Ariyasu, Tomio

    1985-01-01

    The penetration of low frequency sound wave into the fuel deuterium is discussed as for laser fusion. The sound velocity and the attenuation constant due to viscosity are calculated for high density (n = 10 24 -- 10 27 cm -3 , T = 10 -1 -- 10 4 eV) deuterium. The shear viscosity of free electron gas and the bulk viscosity due to ion-ion interaction mainly contribute to the attenuation of sound wave. The sound wave of the frequency below 10 10 Hz can easily penetrate through the compressed fuel deuterium of diameter 1 -- 10 3 μm. (author)

  16. Measurement of the sound power incident on the walls of a reverberation room with near field acoustic holography

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Tiana Roig, Elisabet

    2010-01-01

    area; and it has always been regarded as impossible to measure the sound power that is incident on a wall directly. This paper examines a new method of determining this quantity from sound pressure measurements at positions on the wall using 'statistically optimised near field acoustic holography...

  17. Experiments on second-sound shock waves in superfluid helium

    International Nuclear Information System (INIS)

    Cummings, J.C.; Schmidt, D.W.; Wagner, W.J.

    1978-01-01

    The waveform and velocity of second-sound waves in superfluid helium have been studied experimentally using superconducting, thin-film probes. The second-sound waves were generated with electrical pulses through a resistive film. Variations in pulse power, pulse duration, and bath temperature were examined. As predicted theoretically, the formation of a shock was observed at the leading or trailing edge of the waves depending on bath temperature. Breakdown of the theoretical model was observed for large pulse powers. Accurate data for the acoustic second-sound speed were derived from the measurements of shock-wave velocities and are compared with previous results

  18. Coherent Seismic Arrivals in the P Wave Coda of the 2012 Mw 7.2 Sumatra Earthquake: Water Reverberations or an Early Aftershock?

    Science.gov (United States)

    Fan, Wenyuan; Shearer, Peter M.

    2018-04-01

    Teleseismic records of the 2012 Mw 7.2 Sumatra earthquake contain prominent phases in the P wave train, arriving about 50 to 100 s after the direct P arrival. Azimuthal variations in these arrivals, together with back-projection analysis, led Fan and Shearer (https://doi.org/10.1002/2016GL067785) to conclude that they originated from early aftershock(s), located ˜150 km northeast of the mainshock and landward of the trench. However, recently, Yue et al. (https://doi.org/10.1002/2017GL073254) argued that the anomalous arrivals are more likely water reverberations from the mainshock, based mostly on empirical Green's function analysis of a M6 earthquake near the mainshock and a water phase synthetic test. Here we present detailed back-projection and waveform analyses of three M6 earthquakes within 100 km of the Mw 7.2 earthquake, including the empirical Green's function event analyzed in Yue et al. (https://doi.org/10.1002/2017GL073254). In addition, we examine the waveforms of three M5.5 reverse-faulting earthquakes close to the inferred early aftershock location in Fan and Shearer (https://doi.org/10.1002/2016GL067785). These results suggest that the reverberatory character of the anomalous arrivals in the mainshock coda is consistent with water reverberations, but the origin of this energy is more likely an early aftershock rather than delayed and displaced water reverberations from the mainshock.

  19. Propagation of sound waves in ducts

    DEFF Research Database (Denmark)

    Jacobsen, Finn

    2000-01-01

    Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described.......Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described....

  20. Sound waves in (2+1) dimensional holographic magnetic fluids

    International Nuclear Information System (INIS)

    Buchbinder, Evgeny I.; Buchel, Alex; Vazquez, Samuel E.

    2008-01-01

    We use the AdS/CFT correspondence to study propagation of sound waves in strongly coupled (2+1) dimensional conformal magnetic fluids. Our computation provides a nontrivial consistency check of the viscous magneto-hydrodynamics of Hartnoll-Kovtun-Mueller-Sachdev to leading order in the external field. Depending on the behavior of the magnetic field in the hydrodynamic limit, we show that it can lead to further attenuation of sound waves in the (2+1) dimensional conformal plasma, or reduce the speed of sound. We present both field theory and dual supergravity descriptions of these phenomena. While to the leading order in momenta the dispersion of the sound waves obtained from the dual supergravity description agrees with the one predicted from field theory, we find a discrepancy at higher order. This suggests that further corrections to HKMS magneto-hydrodynamics are necessary.

  1. High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2004-01-01

    Full Text Available Short wavelength ion sound waves (2-4kHz are detected in association with the Langmuir waves (~15-30kHz in the source regions of several local type III radio bursts. They are most probably not due to any resonant wave-wave interactions such as the electrostatic decay instability because their wavelengths are much shorter than those of Langmuir waves. The Langmuir waves occur as coherent field structures with peak intensities exceeding the Langmuir collapse thresholds. Their scale sizes are of the order of the wavelength of an ion sound wave. These Langmuir wave field characteristics indicate that the observed short wavelength ion sound waves are most probably generated during the thermalization of the burnt-out cavitons left behind by the Langmuir collapse. Moreover, the peak intensities of the observed short wavelength ion sound waves are comparable to the expected intensities of those ion sound waves radiated by the burnt-out cavitons. However, the speeds of the electron beams derived from the frequency drift of type III radio bursts are too slow to satisfy the needed adiabatic ion approximation. Therefore, some non-linear process such as the induced scattering on thermal ions most probably pumps the beam excited Langmuir waves towards the lower wavenumbers, where the adiabatic ion approximation is justified.

  2. On Viscosity, Conduction and Sound Waves in the Intracluster Medium

    Energy Technology Data Exchange (ETDEWEB)

    Fabian, A.

    2005-01-25

    Recent X-ray and optical observations of the Perseus cluster indicate that the viscous and conductive dissipation of sound waves is the mechanism responsible for heating the intracluster medium and thus balancing radiative cooling of cluster cores. We discuss this mechanism more generally and show how the specific heating and cooling rates vary with temperature and radius. It appears that the heating mechanism is most effective above 10{sup 7}K, which allows for radiative cooling to proceed within normal galaxy formation but will stifle the growth of very massive galaxies. The scaling of the wavelength of sound waves with cluster temperature and feedback in the system are investigated.

  3. Determining the speed of sound in the air by sound wave interference

    Science.gov (United States)

    Silva, Abel A.

    2017-07-01

    Mechanical waves propagate through material media. Sound is an example of a mechanical wave. In fluids like air, sound waves propagate through successive longitudinal perturbations of compression and decompression. Audible sound frequencies for human ears range from 20 to 20 000 Hz. In this study, the speed of sound v in the air is determined using the identification of maxima of interference from two synchronous waves at frequency f. The values of v were correct to 0 °C. The experimental average value of {\\bar{ν }}\\exp =336 +/- 4 {{m}} {{{s}}}-1 was found. It is 1.5% larger than the reference value. The standard deviation of 4 m s-1 (1.2% of {\\bar{ν }}\\exp ) is an improved value by the use of the concept of the central limit theorem. The proposed procedure to determine the speed of sound in the air aims to be an academic activity for physics classes of scientific and technological courses in college.

  4. Sound wave contours around wind turbine arrays

    International Nuclear Information System (INIS)

    Van Beek, A.; Van Blokland, G.J.

    1993-02-01

    Noise pollution is an important factor in selecting suitable sites for wind turbines in order to realize 1000 MW of wind power as planned by the Dutch government for the year 2000. Therefore an accurate assessment of wind turbine noise is important. The amount of noise pollution from a wind turbine depends on the wind conditions. An existing standard method to assess wind turbine noise is supplemented and adjusted. In the first part of the investigation the method was developed and applied for a solitary sound source. In the second part attention is paid to the use of the method for wind turbine arrays. It appears that the adjusted method results in a shift of the contours of the permitted noise level. In general the contours are 15-25% closer to the wind farm, which means that the minimal permitted distance between houses and wind turbine arrays can be reduced. 14 figs., 1 tab., 4 appendices, 7 refs

  5. Plasma waves observed by sounding rockets

    International Nuclear Information System (INIS)

    Kimura, I.

    1977-01-01

    Observations of plasma wave phenomena have been conducted with several rockets launched at Kagoshima Space Center, Kyushu, Japan, and at Showa Base, Antarctica. This report presents some results of the observations in anticipation of having valuable comments from other plasma physicists, especially from those who are concerned with laboratory plasma. In the K-9M-41 rocket experiment, VLF plasma waves were observed. In this experiment, the electron beam of several tens of uA was emitted from a hot cathode when a positive dc bias changing from 0 to 10V at 1V interval each second was applied to a receiving dipole antenna. The discrete emissions with 'U' shaped frequency spectrum were observed for the dc bias over 3 volts. The U emissions appeared twice per spin period of the rocket. Similar rocket experiment was performed at Showa Base using a loop and dipole antenna and without hot cathode. Emissions were observed with varying conditions. At present, the authors postulate that such emissions may be produced just in the vicinity of a rocket due to a kind of wake effect. (Aoki, K.)

  6. Linear theory of sound waves with evaporation and condensation

    International Nuclear Information System (INIS)

    Inaba, Masashi; Watanabe, Masao; Yano, Takeru

    2012-01-01

    An asymptotic analysis of a boundary-value problem of the Boltzmann equation for small Knudsen number is carried out for the case when an unsteady flow of polyatomic vapour induces reciprocal evaporation and condensation at the interface between the vapour and its liquid phase. The polyatomic version of the Boltzmann equation of the ellipsoidal statistical Bhatnagar–Gross–Krook (ES-BGK) model is used and the asymptotic expansions for small Knudsen numbers are applied on the assumptions that the Mach number is sufficiently small compared with the Knudsen number and the characteristic length scale divided by the characteristic time scale is comparable with the speed of sound in a reference state, as in the case of sound waves. In the leading order of approximation, we derive a set of the linearized Euler equations for the entire flow field and a set of the boundary-layer equations near the boundaries (the vapour–liquid interface and simple solid boundary). The boundary conditions for the Euler and boundary-layer equations are obtained at the same time when the solutions of the Knudsen layers on the boundaries are determined. The slip coefficients in the boundary conditions are evaluated for water vapour. A simple example of the standing sound wave in water vapour bounded by a liquid water film and an oscillating piston is demonstrated and the effect of evaporation and condensation on the sound wave is discussed. (paper)

  7. Sound

    CERN Document Server

    Robertson, William C

    2003-01-01

    Muddled about what makes music? Stuck on the study of harmonics? Dumbfounded by how sound gets around? Now you no longer have to struggle to teach concepts you really don t grasp yourself. Sound takes an intentionally light touch to help out all those adults science teachers, parents wanting to help with homework, home-schoolers seeking necessary scientific background to teach middle school physics with confidence. The book introduces sound waves and uses that model to explain sound-related occurrences. Starting with the basics of what causes sound and how it travels, you'll learn how musical instruments work, how sound waves add and subtract, how the human ear works, and even why you can sound like a Munchkin when you inhale helium. Sound is the fourth book in the award-winning Stop Faking It! Series, published by NSTA Press. Like the other popular volumes, it is written by irreverent educator Bill Robertson, who offers this Sound recommendation: One of the coolest activities is whacking a spinning metal rod...

  8. Sound topology, duality, coherence and wave-mixing an introduction to the emerging new science of sound

    CERN Document Server

    Deymier, Pierre

    2017-01-01

    This book offers an essential introduction to the notions of sound wave topology, duality, coherence and wave-mixing, which constitute the emerging new science of sound. It includes general principles and specific examples that illuminate new non-conventional forms of sound (sound topology), unconventional quantum-like behavior of phonons (duality), radical linear and nonlinear phenomena associated with loss and its control (coherence), and exquisite effects that emerge from the interaction of sound with other physical and biological waves (wave mixing).  The book provides the reader with the foundations needed to master these complex notions through simple yet meaningful examples. General principles for unraveling and describing the topology of acoustic wave functions in the space of their Eigen values are presented. These principles are then applied to uncover intrinsic and extrinsic approaches to achieving non-conventional topologies by breaking the time revers al symmetry of acoustic waves. Symmetry brea...

  9. The energy transport by the propagation of sound waves in wave guides with a moving medium

    NARCIS (Netherlands)

    le Grand, P.

    1977-01-01

    The problem of the propagation of sound waves radiated by a source in a fluid moving with subsonic velocity between two parallel walls or inside a cylindrical tube is considered in [2], The most interesting thing of this problem is that waves may occur with constant amplitude coming from infinity.

  10. Simulation of sound waves using the Lattice Boltzmann Method for fluid flow: Benchmark cases for outdoor sound propagation

    NARCIS (Netherlands)

    Salomons, E.M.; Lohman, W.J.A.; Zhou, H.

    2016-01-01

    Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases:

  11. Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation.

    Science.gov (United States)

    Salomons, Erik M; Lohman, Walter J A; Zhou, Han

    2016-01-01

    Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing.

  12. Electromagnetic reverberation chambers

    CERN Document Server

    Besnier, Philippe

    2013-01-01

    Dedicated to a complete presentation on all aspects of reverberation chambers, this book provides the physical principles behind these test systems in a very progressive manner. The detailed panorama of parameters governing the operation of electromagnetic reverberation chambers details various applications such as radiated immunity, emissivity, and shielding efficiency experiments.In addition, the reader is provided with the elements of electromagnetic theory and statistics required to take full advantage of the basic operational rules of reverberation chambers, including calibration proc

  13. Plane-wave decomposition by spherical-convolution microphone array

    Science.gov (United States)

    Rafaely, Boaz; Park, Munhum

    2004-05-01

    Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

  14. Exploitation of the Reverberant Propagation of Elastic Waves in Structures: Towards a Concept of Low-resource SHM Sensor Network

    Science.gov (United States)

    Moulin, Emmanuel; Benmeddour, Farouk; Achdjian, Hossep; Chehami, Lynda; Assaad, Jamal; de Rosny, Julien; Prada, Claire

    Actual implementation of an efficient SHM system is necessarily hampered by the constraints of power-consumption and intrusive- ness (weight, size, in-service integration) of sensors. In the field of ultrasound-based SHM, conventional methods rely on relatively powerful acoustic sources synchronized with the sensors, and exploit only the first propagated (ballistic) wavepackets. The aim of this paper is to present possible techniques to exploit the whole complexity of reverberation signals, in order to extract the maxi- mum information from limited hardware, software, or power resources. A first aspect is the extraction of statistical properties of the codas of multiply-reflected signals, which can be used to estimate structural properties from a small number of sensors. In this technique, the required signal processing is relatively light and synchronization between the acquisition channels is not necessary. A second aspect is concerned with the possibility of using ambient acoustic sources, naturally present for example in transportation applications, instead of artificial power-consuming ultrasound sources.

  15. Effort variation regularization in sound field reproduction

    DEFF Research Database (Denmark)

    Stefanakis, Nick; Jacobsen, Finn; Sarris, Ioannis

    2010-01-01

    In this paper, active control is used in order to reproduce a given sound field in an extended spatial region. A method is proposed which minimizes the reproduction error at a number of control positions with the reproduction sources holding a certain relation within their complex strengths......), and adaptive wave field synthesis (AWFS), both under free-field conditions and in reverberant rooms. It is shown that effort variation regularization overcomes the problems associated with small spaces and with a low ratio of direct to reverberant energy, improving thus the reproduction accuracy...

  16. The 2011 marine heat wave in Cockburn Sound, southwest Australia

    Directory of Open Access Journals (Sweden)

    T. H. Rose

    2012-07-01

    Full Text Available Over 2000 km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2–4 °C were recorded at a number of locations, and satellite-derived SSTs (sea surface temperatures were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound, a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002–2010. A significant warming event, 2–4 °C in magnitude, persisted for > 8 weeks, and seawater temperatures at 10 to 20 m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being ~ 2 mg l−1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching; fish, invertebrate and macroalgae mortalities; and algal blooms. However, there is a paucity of historical information on ecologically-sensitive habitats and taxa in Cockburn Sound, so that formal examinations of biological responses to the heat wave were not possible. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted.

  17. An oscillation phenomenon of low frequency reverberation in the shallow water and its physical explanation

    Institute of Scientific and Technical Information of China (English)

    LI; Fenghua; LIU; Jianjun; LI; Zhenglin; ZHANG; Renhe

    2005-01-01

    An oscillation phenomenon of the low frequency reverberation intensity was observed in several shallow water reverberation experiments. This phenomenon cannot be explained by the widely used incoherent reverberation theory. In this paper, to explain the observed oscillation phenomenon, a normal mode based coherent reverberation theory is presented. The theoretical analysis and numerical results show that modal interference can cause the regular oscillation phenomenon of the low frequency reverberation intensity, and the oscillation frequency is determined by the normal mode eigen-values. A new method to estimate the bottom sound speed based on the oscillation frequency of reverberation intensity was presented in this paper. The experimental results at three different sites indicate that the bottom sound speed estimated from the oscillation frequency of reverberation intensity agrees with that inverted from Matched Field Processing (MFP) well.

  18. Effect of Sound Waves on Decarburization Rate of Fe-C Melt

    Science.gov (United States)

    Komarov, Sergey V.; Sano, Masamichi

    2018-02-01

    Sound waves have the ability to propagate through a gas phase and, thus, to supply the acoustic energy from a sound generator to materials being processed. This offers an attractive tool, for example, for controlling the rates of interfacial reactions in steelmaking processes. This study investigates the kinetics of decarburization in molten Fe-C alloys, the surface of which was exposed to sound waves and Ar-O2 gas blown onto the melt surface. The main emphasis is placed on clarifying effects of sound frequency, sound pressure, and gas flow rate. A series of water model experiments and numerical simulations are also performed to explain the results of high-temperature experiments and to elucidate the mechanism of sound wave application. This is explained by two phenomena that occur simultaneously: (1) turbulization of Ar-O2 gas flow by sound wave above the melt surface and (2) motion and agitation of the melt surface when exposed to sound wave. It is found that sound waves can both accelerate and inhibit the decarburization rate depending on the Ar-O2 gas flow rate and the presence of oxide film on the melt surface. The effect of sound waves is clearly observed only at higher sound pressures on resonance frequencies, which are defined by geometrical features of the experimental setup. The resonance phenomenon makes it difficult to separate the effect of sound frequency from that of sound pressure under the present experimental conditions.

  19. Digitizing Sound: How Can Sound Waves be Turned into Ones and Zeros?

    Science.gov (United States)

    Vick, Matthew

    2010-10-01

    From MP3 players to cell phones to computer games, we're surrounded by a constant stream of ones and zeros. Do we really need to know how this technology works? While nobody can understand everything, digital technology is increasingly making our lives a collection of "black boxes" that we can use but have no idea how they work. Pursuing scientific literacy should propel us to open up a few of these metaphorical boxes. High school physics offers opportunities to connect the curriculum to sports, art, music, and electricity, but it also offers connections to computers and digital music. Learning activities about digitizing sounds offer wonderful opportunities for technology integration and student problem solving. I used this series of lessons in high school physics after teaching about waves and sound but before optics and total internal reflection so that the concepts could be further extended when learning about fiber optics.

  20. Application of electromagnetic and sound waves in nutritional assessment

    International Nuclear Information System (INIS)

    Heymsfield, S.B.; Rolandelli, R.; Casper, K.; Settle, R.G.; Koruda, M.

    1987-01-01

    Four relatively new techniques that apply electromagnetic or sound waves promise to play a major role in the study of human body composition and in clinical nutritional assessment. Computerized axial tomography, nuclear magnetic resonance, infrared interactance, and ultrasonography provide capabilities for measuring the following: total body and regional fat volume; regional skeletal muscle volume; brain, liver, kidney, heart, spleen, and tumor volume; lean tissue content of triglyceride, iron, and high-energy intermediates; bone density; and cardiac function. Each method is reviewed with regard to basic principles, research and clinical applications, strengths, and limitations.33 references

  1. Jump in the amplitude of a sound wave associated with contraction of a nitrogen discharge

    International Nuclear Information System (INIS)

    Galechyan, G.A.; Mkrtchyan, A.R.; Tavakalyan, L.B.

    1993-01-01

    The use of a sound wave created by an external source and directed along the positive column of a nitrogen discharge in order to make the discharge pass to the contracted state is studied experimentally. A phenomenon involving a jump in the sound wave amplitude, caused by the discharge contraction, is observed and studied. It is established that the amplitude of the sound wave as a function of the discharge current near the jump exhibits hysteresis. It is shown that in the field of a high-intensity sound wave causing the discharge to expand eliminates the jump in the sound amplitude. The dependence of the growth time of the sound amplitude caused by the jump in this quantity on the sound wave intensity is determined. 24 refs., 4 figs., 1 tab

  2. Second sound shock waves in rotating superfluid helium

    International Nuclear Information System (INIS)

    Torczynski, J.R.

    1983-01-01

    Second sound shock waves have been used to examine the breakdown of superfluidity in bulk He II. The maximum counterflow velocity achieved in this manner was measured at a variety of temperatures and pressures. The results are found to agree with predictions of vortex nucleation theories (Langer and Fisher, 1967) in their pressure and temperature dependences although it was shown that dissipation occurred only near the heater. A simple scaling argument is suggested, assuming breakdown occurs near the heater. A vortex dynamics model of breakdown (following the method of Turner, private communication) is developed. To examine the effect of vorticity on breakdown, second sound shocks were produced in rotating helium. Experiments were performed in which the shocks propagated either along or normal to the axis of rotation, called axial and transverse cases, respectively. In both cases the decay was seen to increase monotonically with the rotation rate. Furthermore, the decay was ongoing rather than being confined to a narrow region near the heater. However, the extraordinary dissipation in the transverse case seemed to be related primarily to the arrival of secondary waves from the heater-sidewall boundary. An explanation of this difference is put forth in terms of vortex nucleation in the bulk fluid, using ideas similar to Crocco's Theorem. In order to examine the breakdown of superfluidity away from walls in nonrotation fluid, spherically converging second shocks were produced. The temperature jumps of the waves were measured, and exact numerical solutions of the two-fluid jump conditions (Moody, 1983) were used to calculate the relative velocity in each case

  3. Method of synthesizing silica nanofibers using sound waves

    Science.gov (United States)

    Sharma, Jaswinder K.; Datskos, Panos G.

    2015-09-15

    A method for synthesizing silica nanofibers using sound waves is provided. The method includes providing a solution of polyvinyl pyrrolidone, adding sodium citrate and ammonium hydroxide to form a first mixture, adding a silica-based compound to the solution to form a second mixture, and sonicating the second mixture to synthesize a plurality of silica nanofibers having an average cross-sectional diameter of less than 70 nm and having a length on the order of at least several hundred microns. The method can be performed without heating or electrospinning, and instead includes less energy intensive strategies that can be scaled up to an industrial scale. The resulting nanofibers can achieve a decreased mean diameter over conventional fibers. The decreased diameter generally increases the tensile strength of the silica nanofibers, as defects and contaminations decrease with the decreasing diameter.

  4. Binaural Speech Understanding With Bilateral Cochlear Implants in Reverberation.

    Science.gov (United States)

    Kokkinakis, Kostas

    2018-03-08

    The purpose of this study was to investigate whether bilateral cochlear implant (CI) listeners who are fitted with clinical processors are able to benefit from binaural advantages under reverberant conditions. Another aim of this contribution was to determine whether the magnitude of each binaural advantage observed inside a highly reverberant environment differs significantly from the magnitude measured in a near-anechoic environment. Ten adults with postlingual deafness who are bilateral CI users fitted with either Nucleus 5 or Nucleus 6 clinical sound processors (Cochlear Corporation) participated in this study. Speech reception thresholds were measured in sound field and 2 different reverberation conditions (0.06 and 0.6 s) as a function of the listening condition (left, right, both) and the noise spatial location (left, front, right). The presence of the binaural effects of head-shadow, squelch, summation, and spatial release from masking in the 2 different reverberation conditions tested was determined using nonparametric statistical analysis. In the bilateral population tested, when the ambient reverberation time was equal to 0.6 s, results indicated strong positive effects of head-shadow and a weaker spatial release from masking advantage, whereas binaural squelch and summation contributed no statistically significant benefit to bilateral performance under this acoustic condition. These findings are consistent with those of previous studies, which have demonstrated that head-shadow yields the most pronounced advantage in noise. The finding that spatial release from masking produced little to almost no benefit in bilateral listeners is consistent with the hypothesis that additive reverberation degrades spatial cues and negatively affects binaural performance. The magnitude of 4 different binaural advantages was measured on the same group of bilateral CI subjects fitted with clinical processors in 2 different reverberation conditions. The results of this work

  5. Universal instability of dust ion-sound waves and dust-acoustic waves

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Watanabe, K.

    2002-01-01

    It is shown that the dust ion-sound waves (DISW) and the dust-acoustic waves (DAW) are universally unstable for wave numbers less than some critical wave number. The basic dusty plasma state is assumed to be quasi-neutral with balance of the plasma particle absorption on the dust particles and the ionization with the rate proportional to the electron density. An analytical expression for the critical wave numbers, for the frequencies and for the growth rates of DISW and DAW are found using the hydrodynamic description of dusty plasma components with self-consistent treatment of the dust charge variations and by taking into account the change of the ion and electron distributions in the dust charging process. Most of the previous treatment do not take into account the latter process and do not treat the basic state self-consistently. The critical lengths corresponding to these critical wave numbers can be easily achieved in the existing experiments. It is shown that at the wave numbers larger than the critical ones DISW and DAW have a large damping which was not treated previously and which can be also measured. The instabilities found in the present work on their non linear stage can lead to formation of different types of dust self-organized structures. (author)

  6. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation.

    Science.gov (United States)

    Deymier, P A; Swinteck, N; Runge, K; Deymier-Black, A; Hoying, J B

    2015-01-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  7. ASTROMETRIC REVERBERATION MAPPING

    International Nuclear Information System (INIS)

    Shen Yue

    2012-01-01

    Spatially extended emission regions of active galactic nuclei respond to continuum variations, if such emission regions are powered by energy reprocessing of the continuum. The response from different parts of the reverberating region arrives at different times lagging behind the continuum variation. The lags can be used to map the geometry and kinematics of the emission region (i.e., reverberation mapping, RM). If the extended emission region is not spherically symmetric in configuration and velocity space, reverberation may produce astrometric offsets in the emission region photocenter as a function of time delay and velocity, detectable with future μas to tens of μas astrometry. Such astrometric responses provide independent constraints on the geometric and kinematic structure of the extended emission region, complementary to traditional RM. In addition, astrometric RM is more sensitive to infer the inclination of a flattened geometry and the rotation angle of the extended emission region.

  8. Rarefaction and compression waves of the first sound in superfluid He-II

    International Nuclear Information System (INIS)

    Efimov, V.F.; Kolmakov, G.V.; Lebedeva, E.V.; Mezhov-Deglin, L.P.; Trusov, A.B.

    1999-01-01

    The evolution of the form of the first sound waves, excited by the pulse heater in the superfluid He-II with increase in the thermal pulse Q-capacity, is studied. Propagation of the first sound rarefaction wave (heating wave), subsequent transformation of the rarefaction wave into the compression wave and further into the compression shock wave with Q growth are observed in the fluid, compressed up to 13.3 atm., i.e. it is possible to judge about the change in the heat transfer conditions at the solid body - He-II interface by the change in the sound wave form. It is established that heat expansion of the He-I normal fluid layer, originating at the interface between He-II and the heater by the Q-capacity exceeding certain critical one, is the basic cause of the compression waves excitation in He-II by the pressures of P ≥ 1 atm [ru

  9. The role of reverberation-related binaural cues in the externalization of speech

    DEFF Research Database (Denmark)

    Catic, Jasmina; Santurette, Sébastien; Dau, Torsten

    2015-01-01

    The perception of externalization of speech sounds was investigated with respect to the monaural and binaural cues available at the listeners’ ears in a reverberant environment. Individualized binaural room impulse responses (BRIRs) were used to simulate externalized sound sources via headphones....... The measured BRIRs were subsequently modified such that the proportion of the response containing binaural vs monaural information was varied. Normal-hearing listeners were presented with speech sounds convolved with such modified BRIRs. Monaural reverberation cues were found to be sufficient...

  10. Longitudinal sound waves in a collisionless, quasineutral plasma

    Science.gov (United States)

    Ramos, J. J.

    2017-12-01

    The time evolution of slow sound waves in a homogeneous, collisionless and quasineutral plasma, in particular their Landau damping, is investigated using the kinetic-magnetohydrodynamics formulation of Ramos (J. Plasma Phys. vol. 81, 2015 p. 905810325; vol. 82, 2016 p. 905820607). In this approach, the electric field is eliminated from a closed, hybrid fluid-kinetic system that ensures automatically the fulfilment of the charge neutrality condition. Considering the time dependence of a spatial-Fourier-mode linear perturbation with wavevector parallel to the equilibrium magnetic field, this can be cast as a second-order self-adjoint problem with a continuum spectrum of real and positive squared frequencies. Therefore, a conventional resolution of the identity with a continuum basis of singular normal modes is guaranteed, which simplifies significantly a Van Kampen-like treatment of the Landau damping. The explicit form of such singular normal modes is obtained, along with their orthogonality relations. These are used to derive the damped time evolution of the fluid moments of solutions of initial-value problems, for the most general kinds of initial conditions. The non-zero parallel electric field is not used explicitly in this analysis, but it is calculated from any given solution after the later has been obtained.

  11. Dynamics of unstable sound waves in a non-equilibrium medium at the nonlinear stage

    Science.gov (United States)

    Khrapov, Sergey; Khoperskov, Alexander

    2018-03-01

    A new dispersion equation is obtained for a non-equilibrium medium with an exponential relaxation model of a vibrationally excited gas. We have researched the dependencies of the pump source and the heat removal on the medium thermodynamic parameters. The boundaries of sound waves stability regions in a non-equilibrium gas have been determined. The nonlinear stage of sound waves instability development in a vibrationally excited gas has been investigated within CSPH-TVD and MUSCL numerical schemes using parallel technologies OpenMP-CUDA. We have obtained a good agreement of numerical simulation results with the linear perturbations dynamics at the initial stage of the sound waves growth caused by instability. At the nonlinear stage, the sound waves amplitude reaches the maximum value that leads to the formation of shock waves system.

  12. An 'Orca-stra' of Science and Sound: The Reverberations of Northeast Pacific Whales and How We're Helping People Understand Them Though Games, Demos and Listening

    Science.gov (United States)

    Pelz, M.; Dewey, R. K.; Hoeberechts, M.; Kanes, K.; Ewing, N.

    2015-12-01

    Presented by the Ocean Networks Canada (ONC) Leaning and Engagement team, this demonstration focuses on our strategy for engaging and inspiring the next generation of ocean advocates by introducing them to one of the ocean's most charismatic inhabitants: marine mammals (and don't worry, we don't need any tanks or neoprene suits to do it). Using bioacoustic data, we can bring the essence of the animals with us. ONC, an initiative of the University of Victoria, operates cabled ocean observatories which supply continuous power and Internet connectivity to a broad suite of subsea instruments from the coast to the deep sea. This Internet connectivity permits researchers, students and members of the public to download freely available data onto their computers from anywhere around the globe, in real-time. Our demo focuses on the story of bioacoustics from instrument to animal. When visiting classrooms or hosting booths, we enhance user knowledge and experience by connecting familiar animals with their acoustic data from hydrophones. This includes listening to hydrophone clips collected from the network, analyzing sounds using interactive, real-time software and playing interactive games designed to get participants thinking like a scientist and taking a whale's perspective. For example, participants listen to recordings and guess the sound, identify frequencies and try a working hydrophone. The presentation consists of a suite of activities that meet a broad range of Next Generation Science Standards and includes links to the SoundCloud, https://soundcloud.com/oceannetworkscanada the ONC hydrophone FAQ, http://www.oceannetworks.ca/smart-hydrophone-faq and a classroom ready resource, Shouting Whales http://openschool.bc.ca/shouting_whales/index.html . The included links allow users anywhere to have a similar whale "experience" as the data are classroom ready, accessible and free.

  13. Investigation on acceptable reverberation time at various frequency bands in halls that present amplified music

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Jeong, Cheol-Ho; Støfringsdal, Bård

    2018-01-01

    Subjective ratings from 25 professional musicians and sound engineers were obtained to assess two Danish rock venues of similar size and similar low frequency reverberation times, but different high frequency reverberation times. The musicians judged one hall significantly better than the other......, confirming a hypothesis that rock venues can have a longer reverberation time at mid to high frequencies at least in the empty condition. A fairly long reverberation time in the 63 Hz octave band is found to be acceptable, so the 125 Hz octave band is probably the single most important band to control...... for amplified music....

  14. On the sound absorption coefficient of porous asphalt pavements for oblique incident sound waves

    NARCIS (Netherlands)

    Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Bekke, Dirk; Davy, J.; Don, Ch.; McMinn, T.; Dowsett, L.; Broner, N.; Burgess, M.

    2014-01-01

    A rolling tyre will radiate noise in all directions. However, conventional measurement techniques for the sound absorption of surfaces only give the absorption coefficient for normal incidence. In this paper, a measurement technique is described with which it is possible to perform in situ sound

  15. Soliton emission stimulated by sound wave or external field

    International Nuclear Information System (INIS)

    Malomed, B.A.

    1987-01-01

    Langmuir soliton interaction with ion-acoustic wave results in soliton radiative decay at the expence of emission by the soliton of linear langmuir waves. Intensity of this radiation in the ''subsonic'' regime as well as the rate of energy transfer from acoustic waves to langmuir ones and soliton decay rate are calculated. Three cases are considered: monochromatic acoustic wave, nonmonochromatic wave packet with a wide spectrum, random acoustic field, for which results appear to be qualitatively different. A related problem, concerning the radiation generation by soliton under external electromagnetic wave effect is also considered. Dissipation effect on radiation is investigated

  16. On propagation of sound waves in Q2D conductors in a quantizing magnetic field

    CERN Document Server

    Kirichenko, O V; Galbova, O; Ivanovski, G; Krstovska, D

    2003-01-01

    The attenuation of sound waves propagating normally to the layers of a Q2D conductor is analysed at low enough temperatures when quantization of the energy of conduction electrons results in an oscillatory dependence of the sound attenuation rate on the inverse magnetic field. The sound wave decrement is found for different orientations of the magnetic field with respect to the layers. A layered conductor is shown to be most transparent in the case when the magnetic field is orthogonal to the layers.

  17. On propagation of sound waves in Q2D conductors in a quantizing magnetic field

    International Nuclear Information System (INIS)

    Kirichenko, O.V.; Peschansky, V.G.; Galbova, O.; Ivanovski, G.; Krstovska, D.

    2003-01-01

    The attenuation of sound waves propagating normally to the layers of a Q2D conductor is analysed at low enough temperatures when quantization of the energy of conduction electrons results in an oscillatory dependence of the sound attenuation rate on the inverse magnetic field. The sound wave decrement is found for different orientations of the magnetic field with respect to the layers. A layered conductor is shown to be most transparent in the case when the magnetic field is orthogonal to the layers

  18. Teaching about Mechanical Waves and Sound with a Tuning Fork and the Sun

    Science.gov (United States)

    Leccia, Silvio; Colantonio, Arturo; Puddu, Emanuella; Galano, Silvia; Testa, Italo

    2015-01-01

    Literature in "Physics Education" has shown that students encounter many difficulties in understanding wave propagation. Such difficulties lead to misconceptions also in understanding sound, often used as context to teach wave propagation. To address these issues, we present in this paper a module in which the students are engaged in…

  19. Thermal and viscous effects on sound waves: revised classical theory.

    Science.gov (United States)

    Davis, Anthony M J; Brenner, Howard

    2012-11-01

    In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier-Stokes-Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.

  20. Effect of a sound wave on the stability of an argon discharge

    International Nuclear Information System (INIS)

    Galechyan, G.A.; Karapetyan, D.M.; Tavakalyan, L.B.

    1992-01-01

    The effect of a sound wave on the stability of the positive column of an argon discharge has been studied experimentally in the range of pressures from 40 to 180 torr and discharge currents from 40 to 110 mA in a tube with an interior diameter of 9.8 cm. It is shown that, depending on the intensity of the sound wave and the discharge parameters, sound can cause the positive column either to contract or to leave the contracted state. The electric field strength has been measured as a function of the sound intensity. An analogy between the effect of sound and that of longitudinal pumping of the gas on the argon discharge parameters has been established. The radial temperature of the gas has been studied in an argon discharge as a function of the sound intensity for different gas pressures. A direct relationship has been established between the sign of the detector effect produced by a sound wave in a discharge and the processes of contraction and filamentation of a discharge. 11 refs., 4 figs., 1 tab

  1. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  2. Sensory illusions: Common mistakes in physics regarding sound, light and radio waves

    Science.gov (United States)

    Briles, T. M.; Tabor-Morris, A. E.

    2013-03-01

    Optical illusions are well known as effects that we see that are not representative of reality. Sensory illusions are similar but can involve other senses than sight, such as hearing or touch. One mistake commonly noted among instructors is that students often mis-identify radio signals as sound waves and not as part of the electromagnetic spectrum. A survey of physics students from multiple high schools highlights the frequency of this common misconception, as well as other nuances on this misunderstanding. Many students appear to conclude that, since they experience radio broadcasts as sound, then sound waves are the actual transmission of radio signals and not, as is actually true, a representation of those waves as produced by the translator box, the radio. Steps to help students identify and correct sensory illusion misconceptions are discussed. School of Education

  3. Efficient techniques for wave-based sound propagation in interactive applications

    Science.gov (United States)

    Mehra, Ravish

    Sound propagation techniques model the effect of the environment on sound waves and predict their behavior from point of emission at the source to the final point of arrival at the listener. Sound is a pressure wave produced by mechanical vibration of a surface that propagates through a medium such as air or water, and the problem of sound propagation can be formulated mathematically as a second-order partial differential equation called the wave equation. Accurate techniques based on solving the wave equation, also called the wave-based techniques, are too expensive computationally and memory-wise. Therefore, these techniques face many challenges in terms of their applicability in interactive applications including sound propagation in large environments, time-varying source and listener directivity, and high simulation cost for mid-frequencies. In this dissertation, we propose a set of efficient wave-based sound propagation techniques that solve these three challenges and enable the use of wave-based sound propagation in interactive applications. Firstly, we propose a novel equivalent source technique for interactive wave-based sound propagation in large scenes spanning hundreds of meters. It is based on the equivalent source theory used for solving radiation and scattering problems in acoustics and electromagnetics. Instead of using a volumetric or surface-based approach, this technique takes an object-centric approach to sound propagation. The proposed equivalent source technique generates realistic acoustic effects and takes orders of magnitude less runtime memory compared to prior wave-based techniques. Secondly, we present an efficient framework for handling time-varying source and listener directivity for interactive wave-based sound propagation. The source directivity is represented as a linear combination of elementary spherical harmonic sources. This spherical harmonic-based representation of source directivity can support analytical, data

  4. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    Directory of Open Access Journals (Sweden)

    Magdalena Ryżak

    Full Text Available The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa. We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop. The highest sound pressure level (and the greatest variability was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  5. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    Science.gov (United States)

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  6. Electromagnetic Fields in Reverberant Environments

    NARCIS (Netherlands)

    Vogt-Ardatjew, Robert Andrzej

    2017-01-01

    The phenomenon of resonating electromagnetic (EM) fields has been commonly and successfully exploited in reverberation chambers (RC) for the purpose of electromagnetic compatibility (EMC) testing, as well as modeling multipath environments. Although largely successful, the currently used statistical

  7. Reverberant Acoustic Test Facility (RATF)

    Data.gov (United States)

    Federal Laboratory Consortium — The very large Reverberant Acoustic Test Facility (RATF) at the NASA Glenn Research Center (GRC), Plum Brook Station, is currently under construction and is due to...

  8. Introduction to the physics properties of the waves trough the sound and acoustic didactics

    OpenAIRE

    Bernad Martínez, Jordi

    2017-01-01

    The project makes a journey through sound and acoustics to introduce abstract concepts related with the properties of waves, its processing and acquisition, digitization and compression. Develop a portfolio of basic theory adapted to students, which provides support for practices in order to consolidate and assimilate concepts related to the world of waves and communication. The project aims to link the content with situations or activities related to daily experiences of young students. Curr...

  9. Secondary sound classification for the assessment of focus positioning in shock-wave lithotripsy

    OpenAIRE

    Grennberg, Anders; Almquist, Lars-Olof; Holmner, Nils-Gunnar; Olsson, Lennart

    1993-01-01

    A problem encountered when using acoustic shock-waves for kidney stone disintegration is that the positioning of the focus relative to a stone, for the best possible fragmenting effect, is crtitical. The standard methods for focus positioning are ultrasound or x-ray imaging. These methods are, however, not always sufficient and a better indication of a well positioned focus would be valuable. The secondary sound emitted as a result of each shock-wave has been found to contain valuable informa...

  10. Slow-wave metamaterial open panels for efficient reduction of low-frequency sound transmission

    Science.gov (United States)

    Yang, Jieun; Lee, Joong Seok; Lee, Hyeong Rae; Kang, Yeon June; Kim, Yoon Young

    2018-02-01

    Sound transmission reduction is typically governed by the mass law, requiring thicker panels to handle lower frequencies. When open holes must be inserted in panels for heat transfer, ventilation, or other purposes, the efficient reduction of sound transmission through holey panels becomes difficult, especially in the low-frequency ranges. Here, we propose slow-wave metamaterial open panels that can dramatically lower the working frequencies of sound transmission loss. Global resonances originating from slow waves realized by multiply inserted, elaborately designed subwavelength rigid partitions between two thin holey plates contribute to sound transmission reductions at lower frequencies. Owing to the dispersive characteristics of the present metamaterial panels, local resonances that trap sound in the partitions also occur at higher frequencies, exhibiting negative effective bulk moduli and zero effective velocities. As a result, low-frequency broadened sound transmission reduction is realized efficiently in the present metamaterial panels. The theoretical model of the proposed metamaterial open panels is derived using an effective medium approach and verified by numerical and experimental investigations.

  11. Interaction of Sound with Sound by Novel Mechanisms: Ultrasonic Four-Wave Mixing Mediated by a Suspension and Ultrasonic Three-Wave Mixing at a Free Surface

    Science.gov (United States)

    Simpson, Harry Jay

    Two mechanisms of sound interacting with sound are experimentally and theoretically investigated. Ultrasonic four-wave mixing in a dilute particle suspension, analogous to optical four-wave mixing in photorefractive materials, involves the interaction of three ultrasonic wavefields that produces a fourth scattered wavefield. The experimental configuration consists of two ultrasonic (800 kHz) pump waves that are used to produce a grating in a suspension of 25 μm diameter polymer particles in salt water. The pump waves are counter-propagating, which form a standing wavefield in the suspension and the less compressible particles are attracted to the pressure nodes in response to the time averaged radiation pressure. A higher frequency (2-10 MHz) ultrasonic wavefield is used to probe the resulting grating. The ultrasonic Bragg scattering is then measured. The scattering depends strongly on the response to the pump wave and is an unusual class of acoustical nonlinearity. Investigation of very small amplitude gratings are done by studying the temporal response of the Bragg scattering to a sudden turn on of a moderate amplitude pump wavefield in a previously homogeneous particle suspension. The Bragg scattering has been verified experimentally and is modeled for early-time grating formations using a sinusoidal grating. The larger amplitude gratings are studied in equilibrium and are modeled using an Epstein layer approximation. Ultrasonic three-wave mixing at a free surface involves the interaction of a high amplitude 400 kHz plane wavefield incident at 33^circ on a water-air interface with a normally incident high frequency (4.6 MHz) focused wavefield. The 400 kHz "pump" wavefield reflects from the surface and produces an oscillating surface displacement that forms a local traveling phase grating. Simultaneously the 4.6 MHz "probe" wavefield is reflected from the free surface. The grating scatters the focused probe wavefield and produces (or contributes to) spatially

  12. Maximum likelihood based multi-channel isotropic reverberation reduction for hearing aids

    DEFF Research Database (Denmark)

    Kuklasiński, Adam; Doclo, Simon; Jensen, Søren Holdt

    2014-01-01

    We propose a multi-channel Wiener filter for speech dereverberation in hearing aids. The proposed algorithm uses joint maximum likelihood estimation of the speech and late reverberation spectral variances, under the assumption that the late reverberant sound field is cylindrically isotropic....... The dereverberation performance of the algorithm is evaluated using computer simulations with realistic hearing aid microphone signals including head-related effects. The algorithm is shown to work well with signals reverberated both by synthetic and by measured room impulse responses, achieving improvements...

  13. Sound and sound sources

    DEFF Research Database (Denmark)

    Larsen, Ole Næsbye; Wahlberg, Magnus

    2017-01-01

    There is no difference in principle between the infrasonic and ultrasonic sounds, which are inaudible to humans (or other animals) and the sounds that we can hear. In all cases, sound is a wave of pressure and particle oscillations propagating through an elastic medium, such as air. This chapter...... is about the physical laws that govern how animals produce sound signals and how physical principles determine the signals’ frequency content and sound level, the nature of the sound field (sound pressure versus particle vibrations) as well as directional properties of the emitted signal. Many...... of these properties are dictated by simple physical relationships between the size of the sound emitter and the wavelength of emitted sound. The wavelengths of the signals need to be sufficiently short in relation to the size of the emitter to allow for the efficient production of propagating sound pressure waves...

  14. Propagation and attenuation of sound waves as well as spectrally resolved Rayleigh scattering in weakly ionized plasmas

    International Nuclear Information System (INIS)

    Kopainsky, J.

    1975-01-01

    In weakly ionized plasmas the scattering of electromagnetic waves on free electrons (Thompson scattering) can be neglected as compared with the scattering on bound electrons (Rayleigh scattering). If the scattering process can be described by a fluid dynamical model it is caused by sound waves which are generated or annihilated by the incident electromagnetic wave. The propagation of sound waves results in a shift of the scattered line whereas their absorption within the plasma produces the broadening of the scattered line. The theory of propagation of sound in weakly ionized plasmas is developed and extended to Rayleigh scattering. The results are applied to laser scattering in a weakly ionized hydrogen plasma. (Auth.)

  15. Reading drift in flow rate sensors caused by steady sound waves

    International Nuclear Information System (INIS)

    Maximiano, Celso; Nieble, Marcio D.; Migliavacca, Sylvana C.P.; Silva, Eduardo R.F.

    1995-01-01

    The use of thermal sensors very common for the measurement of small flows of gases. In this kind of sensor a little tube forming a bypass is heated symmetrically, then the temperature distribution in the tube modifies with the mass flow along it. When a stationary wave appears in the principal tube it causes an oscillation of pressure around the average value. The sensor, located between two points of the principal tube, indicates not only the principal mass flow, but also that one caused by the difference of pressure induced by the sound wave. When the gas flows at low pressures the equipment indicates a value that do not correspond to the real. Tests and essays were realized by generating a sound wave in the principal tube, without mass flow, and the sensor detected flux. In order to solve this problem a wave-damper was constructed, installed and tested in the system and it worked satisfactory eliminating with efficiency the sound wave. (author). 2 refs., 3 figs

  16. The generation of sound by vorticity waves in swirling duct flows

    Science.gov (United States)

    Howe, M. S.; Liu, J. T. C.

    1977-01-01

    Swirling flow in an axisymmetric duct can support vorticity waves propagating parallel to the axis of the duct. When the cross-sectional area of the duct changes a portion of the wave energy is scattered into secondary vorticity and sound waves. Thus the swirling flow in the jet pipe of an aeroengine provides a mechanism whereby disturbances produced by unsteady combustion or turbine blading can be propagated along the pipe and subsequently scattered into aerodynamic sound. In this paper a linearized model of this process is examined for low Mach number swirling flow in a duct of infinite extent. It is shown that the amplitude of the scattered acoustic pressure waves is proportional to the product of the characteristic swirl velocity and the perturbation velocity of the vorticity wave. The sound produced in this way may therefore be of more significance than that generated by vorticity fluctuations in the absence of swirl, for which the acoustic pressure is proportional to the square of the perturbation velocity. The results of the analysis are discussed in relation to the problem of excess jet noise.

  17. Interactive Sound Propagation using Precomputation and Statistical Approximations

    Science.gov (United States)

    Antani, Lakulish

    Acoustic phenomena such as early reflections, diffraction, and reverberation have been shown to improve the user experience in interactive virtual environments and video games. These effects arise due to repeated interactions between sound waves and objects in the environment. In interactive applications, these effects must be simulated within a prescribed time budget. We present two complementary approaches for computing such acoustic effects in real time, with plausible variation in the sound field throughout the scene. The first approach, Precomputed Acoustic Radiance Transfer, precomputes a matrix that accounts for multiple acoustic interactions between all scene objects. The matrix is used at run time to provide sound propagation effects that vary smoothly as sources and listeners move. The second approach couples two techniques---Ambient Reverberance, and Aural Proxies---to provide approximate sound propagation effects in real time, based on only the portion of the environment immediately visible to the listener. These approaches lie at different ends of a space of interactive sound propagation techniques for modeling sound propagation effects in interactive applications. The first approach emphasizes accuracy by modeling acoustic interactions between all parts of the scene; the second approach emphasizes efficiency by only taking the local environment of the listener into account. These methods have been used to efficiently generate acoustic walkthroughs of architectural models. They have also been integrated into a modern game engine, and can enable realistic, interactive sound propagation on commodity desktop PCs.

  18. Are communication activities shaped by environmental constraints in reverberating and absorbing forest habitats?

    DEFF Research Database (Denmark)

    Mathevon, Nicolas; Aubin, Thierry; Dabelsteen, Torben

    2004-01-01

    In the dense vegetation of temperate or tropical forests, communication processes are constrained by propagation-induced modifications of the transmitted sounds. The presence of leaves, trunks and branches induces important sound reverberation and absorption leading to diminution of the signal en...

  19. Intermittent large amplitude internal waves observed in Port Susan, Puget Sound

    Science.gov (United States)

    Harris, J. C.; Decker, L.

    2017-07-01

    A previously unreported internal tidal bore, which evolves into solitary internal wave packets, was observed in Port Susan, Puget Sound, and the timing, speed, and amplitude of the waves were measured by CTD and visual observation. Acoustic Doppler current profiler (ADCP) measurements were attempted, but unsuccessful. The waves appear to be generated with the ebb flow along the tidal flats of the Stillaguamish River, and the speed and width of the resulting waves can be predicted from second-order KdV theory. Their eventual dissipation may contribute significantly to surface mixing locally, particularly in comparison with the local dissipation due to the tides. Visually the waves appear in fair weather as a strong foam front, which is less visible the farther they propagate.

  20. GRACILE: a comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

    Directory of Open Access Journals (Sweden)

    M. Ern

    2018-04-01

    Full Text Available Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs and chemistry climate models (CCMs usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases. We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE. GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER. Typical distributions (zonal averages and global maps of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground-based, airborne, or other satellite instruments and for comparison with gravity wave distributions, both resolved and parametrized, in GCMs and CCMs. The GRACILE data set is available as supplementary data at https://doi.org/10.1594/PANGAEA.879658.

  1. GRACILE: a comprehensive climatology of atmospheric gravity wave parameters based on satellite limb soundings

    Science.gov (United States)

    Ern, Manfred; Trinh, Quang Thai; Preusse, Peter; Gille, John C.; Mlynczak, Martin G.; Russell, James M., III; Riese, Martin

    2018-04-01

    Gravity waves are one of the main drivers of atmospheric dynamics. The spatial resolution of most global atmospheric models, however, is too coarse to properly resolve the small scales of gravity waves, which range from tens to a few thousand kilometers horizontally, and from below 1 km to tens of kilometers vertically. Gravity wave source processes involve even smaller scales. Therefore, general circulation models (GCMs) and chemistry climate models (CCMs) usually parametrize the effect of gravity waves on the global circulation. These parametrizations are very simplified. For this reason, comparisons with global observations of gravity waves are needed for an improvement of parametrizations and an alleviation of model biases. We present a gravity wave climatology based on atmospheric infrared limb emissions observed by satellite (GRACILE). GRACILE is a global data set of gravity wave distributions observed in the stratosphere and the mesosphere by the infrared limb sounding satellite instruments High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). Typical distributions (zonal averages and global maps) of gravity wave vertical wavelengths and along-track horizontal wavenumbers are provided, as well as gravity wave temperature variances, potential energies and absolute momentum fluxes. This global data set captures the typical seasonal variations of these parameters, as well as their spatial variations. The GRACILE data set is suitable for scientific studies, and it can serve for comparison with other instruments (ground-based, airborne, or other satellite instruments) and for comparison with gravity wave distributions, both resolved and parametrized, in GCMs and CCMs. The GRACILE data set is available as supplementary data at https://doi.org/10.1594/PANGAEA.879658" target="_blank">https://doi.org/10.1594/PANGAEA.879658.

  2. An open-structure sound insulator against low-frequency and wide-band acoustic waves

    Science.gov (United States)

    Chen, Zhe; Fan, Li; Zhang, Shu-yi; Zhang, Hui; Li, Xiao-juan; Ding, Jin

    2015-10-01

    To block sound, i.e., the vibration of air, most insulators are based on sealed structures and prevent the flow of the air. In this research, an acoustic metamaterial adopting side structures, loops, and labyrinths, arranged along a main tube, is presented. By combining the accurately designed side structures, an extremely wide forbidden band with a low cut-off frequency of 80 Hz is produced, which demonstrates a powerful low-frequency and wide-band sound insulation ability. Moreover, by virtue of the bypass arrangement, the metamaterial is based on an open structure, and thus air flow is allowed while acoustic waves can be insulated.

  3. Propagation of sound wave in high density deuterium at high temperatures

    International Nuclear Information System (INIS)

    Inoue, Kazuko; Ariyasu, Tomio

    1986-01-01

    The velocity and the attenuation constant of sound wave have been calculated for high density (10 24 ∼ 10 27 /cm 3 ) deuterium at high temperatures (10 -1 ∼ 10 4 eV). This calculation was made to understand the fuel properties in inertial confinement fusion and to obtain the basic data for pellet design. The isentropic sound wave which propagates in deuterium in plasma state at temperature T i = T e , is dealt with. The velocity is derived using the modulus of bulk elasticity of the whole system and the modulus of shear elasticity due to ion-ion interaction. For the calculation of attenuation constant, the bulk and shear viscosity due to ion-ion interaction, the shear viscosity of free electron gas, and the thermal conductivity due to free electrons are considered. The condition of frequency for the existence of such isentropic sound wave is discussed. The possibility of penetration into the fuel pellet in inertial confinement fusion is also discussed. The followings have been found: (1) The sound velocity is determined mainly from the bulk elasticity. The contribution of the shear elasticity is small. The velocity ranges from 2.8 x 10 6 to 1.5 x 10 8 cm/s in the above mentioned temperature and density regions. (2) The coefficient of attenuation constant with respect to ω 2 /2ρu 3 plotted versus temperature with the parameter of density shows a minimum. At temperatures below this minimum, the attenuation comes mainly from the bulk viscosity due to ion-ion interaction and the shear viscosity due to free electron gas. At temperatures above this minimum, the sound is attenuated mainly by the thermal conductivity due to electrons. (3) The condition for the existence of such adiabatic sound wave, is satisfied with the frequency less than 10 10 Hz. But, as for the pellet design, the wave length of sound with frequency less than 10 10 Hz is longer than the diameter of pellet when compressed highly. (author)

  4. Sound waves and dynamics of superfluid Fermi gases in optical lattices

    International Nuclear Information System (INIS)

    Zhang Aixia; Xue Jukui

    2009-01-01

    The sound waves, the stability of Bloch waves, the Bloch oscillation, and the self-trapping phenomenon in interacting two-component Fermi gases throughout the BEC-BCS crossover in one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) optical lattices are discussed in detail. Within the hydrodynamical theory and by using the perturbative and tight-binding approximation, sound speed in both weak and tight 1D, 2D, 3D optical lattices, and the criteria for occurrences of instability of Bloch waves and self-trapping of Fermi gases along the whole BEC-BCS crossover in tight 1D, 2D, 3D optical lattices are obtained analytically. The results show that the sound speed, the criteria for occurrences of instability of Bloch waves and self-trapping, and the destruction of Bloch oscillation are modified dramatically by the lattice parameters (lattice dimension and lattice strength), the atom density or atom number, and the atom interaction.

  5. Spatial Statistics of Deep-Water Ambient Noise; Dispersion Relations for Sound Waves and Shear Waves

    Science.gov (United States)

    2015-09-30

    bi-linear hydrophone 8 array to locate biological sound sources on a coral reef ”, J. Acoust. Soc. Am. 137, 30-41 (2015) [published, refereed]. 3...Friedlander, A. K. Gregg, S. A. Sandin and M. J. Buckingham, “The origins of ambient biological sound from coral reef ecosystems in the Line Islands...descending under gravity and, after releasing a drop weight at a pre-assigned depth, returning to the surface under buoyancy. Throughout the descent and

  6. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  7. Coupling of Rayleigh-like waves with zero-sound modes in normal 3He

    International Nuclear Information System (INIS)

    Bogacz, S.A.; Ketterson, J.B.

    1985-01-01

    The Landau kinetic equation is solved in the collisionless regime for a sample of normal 3 He excited by a surface perturbation of arbitrary ω and k. The boundary condition for the nonequilibrium particle distribution is determined for the case of specular reflection of the elementary excitations at the interface. Using the above solution, the energy flux through the boundary is obtained as a function of the surface wave velocity ω/k. The absorption spectrum and its frequency derivative are calculated numerically for typical values of temperature and pressure. The spectrum displays a sharp, resonant-like maximum concentrated at the longitudinal sound velocity and a sharp maximum of the derivative concentrated at the transverse sound velocity. The energy transfer is cut off discontinuously below the Fermi velocity. An experimental measurement of the energy transfer spectrum would permit a determination of both zero-sound velocities and the Fermi velocity with spectroscopic precision

  8. Deltas, freshwater discharge, and waves along the Young Sound, NE Greenland

    DEFF Research Database (Denmark)

    Kroon, Aart; Abermann, Jakob; Bendixen, Mette

    2017-01-01

    , and bathymetry), fluvial discharges and associated sediment load, and processes by waves and currents. Main factors steering the Arctic fluvial discharges into the Young Sound are the snow and ice melt and precipitation in the catchment, and extreme events like glacier lake outburst floods (GLOFs). Waves......A wide range of delta morphologies occurs along the fringes of the Young Sound in Northeast Greenland due to spatial heterogeneity of delta regimes. In general, the delta regime is related to catchment and basin characteristics (geology, topography, drainage pattern, sediment availability...... are subordinate and only rework fringes of the delta plain forming sandy bars if the exposure and fetch are optimal. Spatial gradients and variability in driving forces (snow and precipitation) and catchment characteristics (amount of glacier coverage, sediment characteristics) as well as the strong and local...

  9. Simultaneous observations of E- and B-ULF waves aboard a sounding rocket payload

    International Nuclear Information System (INIS)

    Kloecker, N.; Luehr, H.; Grabowski, R.

    1980-01-01

    Magnetic and electric field variations in the frequency range of 0.5 to 4 Hz were made on a payload flown within the IMS sounding rocket campaign 'Substormphenomena'. The payload was launched into an auroral break-up. The waves show amplitudes up to 100 nT in B and 100 mV/m in E. Mutual correlation of B and E as well as correlation with electron precipitation are observed. The energy flux of the waves and the particles are equally directed and of the same order of magnitude. (Auth.)

  10. Underwater Sound Levels at a Wave Energy Device Testing Facility in Falmouth Bay, UK.

    Science.gov (United States)

    Garrett, Joanne K; Witt, Matthew J; Johanning, Lars

    2016-01-01

    Passive acoustic monitoring devices were deployed at FaBTest in Falmouth Bay, UK, a marine renewable energy device testing facility during trials of a wave energy device. The area supports considerable commercial shipping and recreational boating along with diverse marine fauna. Noise monitoring occurred during (1) a baseline period, (2) installation activity, (3) the device in situ with inactive power status, and (4) the device in situ with active power status. This paper discusses the preliminary findings of the sound recording at FabTest during these different activity periods of a wave energy device trial.

  11. Kinetic theory for radiation interacting with sound waves in ultrarelativistic pair plasmas

    International Nuclear Information System (INIS)

    Marklund, Mattias; Shukla, Padma K.; Stenflo, Lennart

    2006-01-01

    A kinetic theory for radiation interacting with sound waves in an ultrarelativistic electron-positron plasma is developed. It is shown that the effect of a spatial spectral broadening of the electromagnetic pulse is to introduce a reduction of the growth rates for the decay and modulational instabilities. Such spectral broadening could be due to a finite pulse coherence length, or through the use of random phase filters, and would stabilize the propagation of electromagnetic pulses

  12. Sound Shell Model for Acoustic Gravitational Wave Production at a First-Order Phase Transition in the Early Universe

    Science.gov (United States)

    Hindmarsh, Mark

    2018-02-01

    A model for the acoustic production of gravitational waves at a first-order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that the sound waves are linear and that their power spectrum is determined by the characteristic form of the sound shell around the expanding bubble. The predicted power spectrum has two length scales, the average bubble separation and the sound shell width when the bubbles collide. The peak of the power spectrum is at wave numbers set by the sound shell width. For a higher wave number k , the power spectrum decreases to k-3. At wave numbers below the inverse bubble separation, the power spectrum goes to k5. For bubble wall speeds near the speed of sound where these two length scales are distinguished, there is an intermediate k1 power law. The detailed dependence of the power spectrum on the wall speed and the other parameters of the phase transition raises the possibility of their constraint or measurement at a future space-based gravitational wave observatory such as LISA.

  13. Sound Shell Model for Acoustic Gravitational Wave Production at a First-Order Phase Transition in the Early Universe.

    Science.gov (United States)

    Hindmarsh, Mark

    2018-02-16

    A model for the acoustic production of gravitational waves at a first-order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that the sound waves are linear and that their power spectrum is determined by the characteristic form of the sound shell around the expanding bubble. The predicted power spectrum has two length scales, the average bubble separation and the sound shell width when the bubbles collide. The peak of the power spectrum is at wave numbers set by the sound shell width. For a higher wave number k, the power spectrum decreases to k^{-3}. At wave numbers below the inverse bubble separation, the power spectrum goes to k^{5}. For bubble wall speeds near the speed of sound where these two length scales are distinguished, there is an intermediate k^{1} power law. The detailed dependence of the power spectrum on the wall speed and the other parameters of the phase transition raises the possibility of their constraint or measurement at a future space-based gravitational wave observatory such as LISA.

  14. Sound absorption in a field of a strong electromagnetic wave in a quantizied magnetic field

    International Nuclear Information System (INIS)

    Chajkovskij, I.A.

    1974-01-01

    A coefficient of sound absorption GAMMA in a semiconductor and semi-metal in the quantized magnetic field is calculated for a system exposed to a field of strong electromagnetic radiation. The cases E parallel H and E orthogonal H are considered. Along with the already known strong oscillations of sound absorption in magnetic fields, the absorption spectrum GAMMAsub(par) and GAMMAsub(orth) shows new oscillations representing a manifestation of the quasi-energetic electron spectrum in the field of a strong electromagnetic wave. The oscillation height at E parallel H is modulated by the electromagnetic field. It is shown that the ratio GAMMAsub(par)/GAMMAsub(orth) allows the determination of the effective mass of the carriers

  15. Dynamic PIV measurement on the effect of sound wave in upper plenum of boiling water reactor

    International Nuclear Information System (INIS)

    Kumagai, Kosuke; Someya, Satoshi; Okamoto, Koji

    2008-01-01

    In one of the power uprated plants in the United States, the steam dryer breakages due to fatigue fracture occurred. It is conceivable that the increased steam flow passing through the branches caused a self-induced vibration with the propagation of sound wave into the steam-dome. The resonance among the structure, flow and the pressure fluctuation resulted in the breakages. To understand the basic mechanism of the resonance, previous researches were done by a point measurement of the pressure and by a phase averaged measurement of the flow, while it was difficult to detect the interaction among them by the conventional method. In the preliminary study, Dynamic Particle Image Velocimetry (PIV) System was applied to investigate the effect of sound on the flow. (author)

  16. Sound wave generation by a spherically symmetric outburst and AGN feedback in galaxy clusters

    Science.gov (United States)

    Tang, Xiaping; Churazov, Eugene

    2017-07-01

    We consider the evolution of an outburst in a uniform medium under spherical symmetry, having in mind active galactic nucleus feedback in the intracluster medium. For a given density and pressure of the medium, the spatial structure and energy partition at a given time tage (since the onset of the outburst) are fully determined by the total injected energy Einj and the duration tb of the outburst. We are particularly interested in the late phase evolution when the strong shock transforms into a sound wave. We studied the energy partition during such transition with different combinations of Einj and tb. For an instantaneous outburst with tb → 0, which corresponds to the extension of classic Sedov-Taylor solution with counter-pressure, the fraction of energy that can be carried away by sound waves is ≲12 per cent of Einj. As tb increases, the solution approaches the 'slow piston' limit, with the fraction of energy in sound waves approaching zero. We then repeat the simulations using radial density and temperature profiles measured in Perseus and M87/Virgo clusters. We find that the results with a uniform medium broadly reproduce an outburst in more realistic conditions once proper scaling is applied. We also develop techniques to map intrinsic properties of an outburst (Einj, tb and tage) to the observables like the Mach number of the shock and radii of the shock and ejecta. For the Perseus cluster and M87, the estimated (Einj, tb and tage) agree with numerical simulations tailored for these objects with 20-30 per cent accuracy.

  17. Wireless Communications in Reverberant Environments

    Science.gov (United States)

    2015-01-01

    Dedications For Mom, Dad , Michelle, Tyler, and Emily. iii Acknowledgments Moshe once told us that we would learn more from our lab mates than we would...in reverberant environments, such as industrial facilities, naval vessels, aircraft, and spacecraft, has proven challenging, because rich ...environments are characterized by rich electromagnetic scattering which is a result of the low absorption of electromagnetic radiation by the surfaces

  18. A Novel Approach for Blind Estimation of Reverberation Time using Rayleigh Distribution Model

    Directory of Open Access Journals (Sweden)

    AMAD HAMZA

    2016-10-01

    Full Text Available In this paper a blind estimation approach is proposed which directly utilizes the reverberant signal for estimating the RT (Reverberation Time.For estimation a very well-known method is used; MLE (Maximum Likelihood Estimation. Distribution of the decay rate is the core of the proposed method and can be achieved from the analysis of decay curve of the energy of the sound or from enclosure impulse response. In a pre-existing state of the art method Laplace distribution is used to model reverberation decay. The method proposed in this paper make use of the Rayleigh distribution and a spotting approach for modelling decay rate and identifying region of free decay in reverberant signal respectively. Motivation for the paper was deduced from the fact, when the reverberant speech RT falls in specific range then the signals decay rate impersonate Rayleigh distribution. On the basis of results of the experiments carried out for numerous reverberant signal it is clear that the performance and accuracy of the proposed method is better than other pre-existing methods

  19. A Novel Approach for Blind Estimation of Reverberation Time using Rayleigh Distribution Model

    International Nuclear Information System (INIS)

    Hamza, A.; Jan, T.; Ali, A.

    2016-01-01

    In this paper a blind estimation approach is proposed which directly utilizes the reverberant signal for estimating the RT (Reverberation Time). For estimation a very well-known method is used; MLE (Maximum Likelihood Estimation). Distribution of the decay rate is the core of the proposed method and can be achieved from the analysis of decay curve of the energy of the sound or from enclosure impulse response. In a pre-existing state of the art method Laplace distribution is used to model reverberation decay. The method proposed in this paper make use of the Rayleigh distribution and a spotting approach for modelling decay rate and identifying region of free decay in reverberant signal respectively. Motivation for the paper was deduced from the fact, when the reverberant speech RT falls in specific range then the signals decay rate impersonate Rayleigh distribution. On the basis of results of the experiments carried out for numerous reverberant signal it is clear that the performance and accuracy of the proposed method is better than other pre-existing methods. (author)

  20. Gravitational waves from the sound of a first order phase transition.

    Science.gov (United States)

    Hindmarsh, Mark; Huber, Stephan J; Rummukainen, Kari; Weir, David J

    2014-01-31

    We report on the first three-dimensional numerical simulations of first-order phase transitions in the early Universe to include the cosmic fluid as well as the scalar field order parameter. We calculate the gravitational wave (GW) spectrum resulting from the nucleation, expansion, and collision of bubbles of the low-temperature phase, for phase transition strengths and bubble wall velocities covering many cases of interest. We find that the compression waves in the fluid continue to be a source of GWs long after the bubbles have merged, a new effect not taken properly into account in previous modeling of the GW source. For a wide range of models, the main source of the GWs produced by a phase transition is, therefore, the sound the bubbles make.

  1. Preference of reverberation time for musicians and audience of the Javanese traditional gamelan music

    Science.gov (United States)

    Suyatno; Tjokronegoro, H. A.; Merthayasa, I. G. N.; Supanggah, R.

    2016-11-01

    This paper presents results of an investigation of room acoustic parameters those are appropriated particularly to perform a Javanese gamelan. The acoustic parameters were obtained by analysing simulated sounds of performance. Those simulated sounds were obtained by sound convolution technique of a dry sound signal of Javanese gamelan performance with impulse responses rooms whose appropriated reverberation time. The reverberation time were varied between 1.0s to 1.8s, those belong to the characteristic of Pendopo Mangkunegaran Surakarta. In this case, Pendopo Mangkunegaran is assumed as one of the most suitable concert halls for Javanese gamelan performance. To obtain the acoustic parameters, we used a psycho-acoustics measurement based on paired comparison test that having different of acoustic parameters to determine the most comfortable one to majority of respondents. The respondents who have participated in this research composed of a group of professional musicians of Javanese gamelan and groups of audience who are not musician, nevertheless part of them were familiar with Javanese gamelan music. The comparison test gave results and showed majority of respondents of group of musicians had a notion sound reverberation time of 1.2s was most comfortable. This corresponds to +6.2dB, clarity and 74% definition. It means the appropriate acoustic condition allows musicians to recognize and distinguish clearly sound of each instrument being played. Meanwhile, group of audience had a notion reverberation time in a range of 1.2s - 1.6s was most comfortable. This range of reverberation time corresponds to +4dB to +6.2dB of clarity, and 66% to 74% of definition.

  2. Effects of different diffuser types on the diffusivity in reverberation chambers

    DEFF Research Database (Denmark)

    Nolan, Melanie; Vercammen, Martijn; Jeong, Cheol-Ho

    2015-01-01

    Knowledge of sound absorption properties of typical building materials is essential for all tasks related to room acoustic design. The Sabine absorption coefficient is measured in a reverberation chamber according to the international standard ISO 354. It is known that inter-laboratory reproducib...

  3. Illustrations and supporting texts for sound standing waves of air columns in pipes in introductory physics textbooks

    Directory of Open Access Journals (Sweden)

    Liang Zeng

    2014-07-01

    Full Text Available In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly assigned to two groups of 15 each. Both groups were administered a presurvey. Then, group A read the air molecule motion illustration handout, and group B read a traditional textbook illustration handout; both groups were administered postsurveys. Subsequently, the procedure was reversed: group B read the air molecule motion illustration handout and group A read the traditional textbook illustration handout. This was followed by a second postsurvey along with an exit research questionnaire. The study found that the majority of students experienced meaningful learning and stated that they understood sound standing wave phenomena significantly better using the air molecule motion illustration approach. This finding provides a method for physics education researchers to design illustrations for abstract sound standing wave concepts, for publishers to improve their illustrations with supporting text, and for instructors to facilitate deeper learning in their students on sound standing waves.

  4. Measurement on the effect of sound wave in upper plenum of boiling water reactor

    International Nuclear Information System (INIS)

    Kumagai, Kosuke; Someya, Satoshi; Okamoto, Koji

    2009-01-01

    In recent years, the power uprate of Boiling Water Reactors have been conducted at several existing power plants as a way to improve plant economy. In one of the power uprated plants (117.8% uprates) in the United States, the steam dryer breakages due to fatigue fracture occurred. It is conceivable that the increased steam flow passing through the branches caused a self-induced vibration with the propagation of sound wave into the steam-dome. The resonance among the structure, flow and the pressure fluctuation resulted in the breakages. To understand the basic mechanism of the resonance, previous researches were done by a point measurement of the pressure and by a phase averaged measurement of the flow, while it was difficult to detect the interaction among them by the conventional method. In this study, Dynamic Particle Image Velocimetry (PIV) System was applied to investigate the effect of sound on natural convection and forced convection. Especially, when the phases of acoustic sources were different, various acoustic wave effects were checked. (author)

  5. Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

    Science.gov (United States)

    McMullen, Katherine Y.; Poppe, Lawrence J.; Parker, Castle E.

    2015-01-01

    Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

  6. Statistical properties of kinetic and total energy densities in reverberant spaces

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Molares, Alfonso Rodriguez

    2010-01-01

    Many acoustical measurements, e.g., measurement of sound power and transmission loss, rely on determining the total sound energy in a reverberation room. The total energy is usually approximated by measuring the mean-square pressure (i.e., the potential energy density) at a number of discrete....... With the advent of a three-dimensional particle velocity transducer, it has become somewhat easier to measure total rather than only potential energy density in a sound field. This paper examines the ensemble statistics of kinetic and total sound energy densities in reverberant enclosures theoretically...... positions. The idea of measuring the total energy density instead of the potential energy density on the assumption that the former quantity varies less with position than the latter goes back to the 1930s. However, the phenomenon was not analyzed until the late 1970s and then only for the region of high...

  7. Shielding Effectiveness Measurements using a Reverberation Chamber

    NARCIS (Netherlands)

    Leferink, Frank Bernardus Johannes; Bergsma, J.G.; Bergsma, Hans; van Etten, Wim

    2006-01-01

    Shielding effectiveness measurements have been performed using a reverberation chamber. The reverberation chamber methodology as we1l as the measurement setup is described and some results are given. Samples include glass reinforced plastic panels, aluminum panels with many holes, wire mesh, among

  8. Rayleigh scattering of a cylindrical sound wave by an infinite cylinder.

    Science.gov (United States)

    Baynes, Alexander B; Godin, Oleg A

    2017-12-01

    Rayleigh scattering, in which the wavelength is large compared to the scattering object, is usually studied assuming plane incident waves. However, full Green's functions are required in a number of problems, e.g., when a scatterer is located close to the ocean surface or the seafloor. This paper considers the Green's function of the two-dimensional problem that corresponds to scattering of a cylindrical wave by an infinite cylinder embedded in a homogeneous fluid. Soft, hard, and impedance cylinders are considered. Exact solutions of the problem involve infinite series of products of Bessel functions. Here, simple, closed-form asymptotic solutions are derived, which are valid for arbitrary source and receiver locations outside the cylinder as long as its diameter is small relative to the wavelength. The scattered wave is given by the sum of fields of three linear image sources. The viability of the image source method was anticipated from known solutions of classical electrostatic problems involving a conducting cylinder. The asymptotic acoustic Green's functions are employed to investigate reception of low-frequency sound by sensors mounted on cylindrical bodies.

  9. The role of reverberation-related binaural cues in the externalization of speech.

    Science.gov (United States)

    Catic, Jasmina; Santurette, Sébastien; Dau, Torsten

    2015-08-01

    The perception of externalization of speech sounds was investigated with respect to the monaural and binaural cues available at the listeners' ears in a reverberant environment. Individualized binaural room impulse responses (BRIRs) were used to simulate externalized sound sources via headphones. The measured BRIRs were subsequently modified such that the proportion of the response containing binaural vs monaural information was varied. Normal-hearing listeners were presented with speech sounds convolved with such modified BRIRs. Monaural reverberation cues were found to be sufficient for the externalization of a lateral sound source. In contrast, for a frontal source, an increased amount of binaural cues from reflections was required in order to obtain well externalized sound images. It was demonstrated that the interaction between the interaural cues of the direct sound and the reverberation strongly affects the perception of externalization. An analysis of the short-term binaural cues showed that the amount of fluctuations of the binaural cues corresponded well to the externalization ratings obtained in the listening tests. The results further suggested that the precedence effect is involved in the auditory processing of the dynamic binaural cues that are utilized for externalization perception.

  10. Plasma oscillations and sound waves in collision-dominated two-component plasmas

    International Nuclear Information System (INIS)

    Hansen, J.P.; Sjoegren, L.

    1982-01-01

    Charge, mass, and electron density fluctuation spectra of strongly correlated, fully ionized two-component plasmas within the framework of the Mori--Zwanzig memory function formalism are analyzed. All dynamical correlation functions are expressed in terms of the memory functions of the ion and electron velocity autocorrelation functions by a generalized effective field approximation which preserves the exact initial values (i.e., static correlations). The theory reduces correctly to the mean field (or collisionless Vlasov) results in the weak coupling limit, and yields charge density fluctuation spectra in good agreement with available computer simulation data, as well as reasonable estimates of the transport coefficients. The collisional damping and frequency shift of the plasma oscillation mode are sizeable, even in the long wavelength limit. The theory also predicts the propagation of well-defined sound waves in dense plasmas in thermal equilibrium

  11. Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation

    International Nuclear Information System (INIS)

    Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.

    1993-01-01

    Changes in the composition of trace gases in the earth's atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth's climate that may be caused by radiatively active gases introduced into the earth's atmosphere by man's activities. Radiatively active trace gases produce temperature changes in the earth's atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992

  12. Third sound: the propagation of waves on the surface of superfluid helium with healing and relaxation

    International Nuclear Information System (INIS)

    Johnson, R.S.

    1984-01-01

    The propagation of surface waves - that is 'third' sound -on superfluid helium is considered. The fluid is treated as a continuum, using the two-fluid model of Landau, and incorporating the effects of healing, relaxation, thermal conductivity and Newtonian viscosity. A linear theory is developed which includes some discussion of the matching to the outer regions of the vapour. This results in a comprehensive propagation speed for linear waves, although a few properties of the flow are left undetermined at this order. A nonlinear theory is then outlined which leads to the Burgers equation in an appropriate far field, and enables the leading-order theory to be concluded. Some numerical results, for two temperatures, are presented by first recording the Helmholtz free energy as a polynomial in densities, but only the equilibrium state can be satisfactorily reproduced. The propagation speed, as a function of film thickness, is roughly estimated. The looked-for reduction in the predicted speeds is evident, but the magnitude of this reduction is too large for very thin films. However, these analytical results should prove more effective when a complete and accurate description of the Helmholtz free energy is available. (author)

  13. Making Sound Connections

    Science.gov (United States)

    Deal, Walter F., III

    2007-01-01

    Sound provides and offers amazing insights into the world. Sound waves may be defined as mechanical energy that moves through air or other medium as a longitudinal wave and consists of pressure fluctuations. Humans and animals alike use sound as a means of communication and a tool for survival. Mammals, such as bats, use ultrasonic sound waves to…

  14. Modeling of "Stripe" Wave Phenomena Seen by the CHARM II and ACES Sounding Rockets

    Science.gov (United States)

    Dombrowski, M. P.; Labelle, J. W.

    2010-12-01

    Two recent sounding-rocket missions—CHARM II and ACES—have been launched from Poker Flat Research Range, carrying the Dartmouth High-Frequency Experiment (HFE) among their primary instruments. The HFE is a receiver system which effectively yields continuous (100% duty cycle) E-field waveform measurements up to 5 MHz. The CHARM II sounding rocket was launched 9:49 UT on 15 February 2010 into a substorm, while the ACES mission consisted of two rockets, launched into quiet aurora at 9:49 and 9:50 UT on 29 January 2009. At approximately 350 km on CHARM II and the ACES High-Flyer, the HFE detected short (~2s) bursts of broadband (200-500 kHz) noise with a 'stripe' pattern of nulls imposed on it. These nulls have 10 to 20 kHz width and spacing, and many show a regular, non-linear frequency-time relation. These events are different from the 'stripes' discussed by Samara and LaBelle [2006] and Colpitts et al. [2010], because of the density of the stripes, the non-linearity, and the appearance of being an absorptive rather than emissive phenomenon. These events are similar to 'stripe' features reported by Brittain et al. [1983] in the VLF range, explained as an interference pattern between a downward-traveling whistler-mode wave and its reflection off the bottom of the ionosphere. Following their analysis method, we modeled our stripes as higher-frequency interfering whistlers reflecting off of a density gradient. This model predicts the near-hyperbolic frequency-time curves and high density of the nulls, and therefore shows promise at explaining the new observations.

  15. Wave field synthesis, adaptive wave field synthesis and ambisonics using decentralized transformed control: Potential applications to sound field reproduction and active noise control

    Science.gov (United States)

    Gauthier, Philippe-Aubert; Berry, Alain; Woszczyk, Wieslaw

    2005-09-01

    Sound field reproduction finds applications in listening to prerecorded music or in synthesizing virtual acoustics. The objective is to recreate a sound field in a listening environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. Classical WFS, therefore, does not perform well in a real reproduction space such as room. Previous work has suggested that it is physically possible to reproduce a progressive wave field in-room situation using active control approaches. In this paper, a formulation of adaptive wave field synthesis (AWFS) introduces practical possibilities for an adaptive sound field reproduction combining WFS and active control (with WFS departure penalization) with a limited number of error sensors. AWFS includes WFS and closed-loop ``Ambisonics'' as limiting cases. This leads to the modification of the multichannel filtered-reference least-mean-square (FXLMS) and the filtered-error LMS (FELMS) adaptive algorithms for AWFS. Decentralization of AWFS for sound field reproduction is introduced on the basis of sources' and sensors' radiation modes. Such decoupling may lead to decentralized control of source strength distributions and may reduce computational burden of the FXLMS and the FELMS algorithms used for AWFS. [Work funded by NSERC, NATEQ, Université de Sherbrooke and VRQ.] Ultrasound/Bioresponse to

  16. Dynamic PIV measurement of the effect of sound waves in the upper plenum of the boiling water reactor

    International Nuclear Information System (INIS)

    Kumagai, Kosuke; Someya, Satoshi; Okamoto, Koji

    2008-01-01

    In recent years, power uprating of boiling power reactors has been conducted at several existing power plants in order to improve plant economy. In one power uprated plant (117.8% uprate) in the United States, steam dryer breakages due to fatigue fracture occurred. It is conceivable that the increased steam flow passing through the branches caused a self-induced vibration with the propagation of sound waves into the steam-dome. The resonance among the structure, the flow, and the pressure fluctuation resulted in the breakages. In order to clarify the basic mechanism of the resonance, previous studies were performed by conducting a point measurement of the pressure and a phase averaged measurement of the flow, although detecting the interaction among the structure, the flow, and the pressure fluctuation by the conventional method was difficult. In a preliminary study, a dynamic Particle Image Velocimetry (PIV) system was used to investigate the effect of sound on the flow. A dynamic PIV system is the newest entrant to the field of fluid flow measurement. Its paramount advantage is the instantaneous global evaluation of conditions over a plane extended across the entire velocity field. Using the dynamic PIV system, the influence of sound waves on the flow field was measured. As a result, when two speakers were placed diagonally and sound waves were presented in the same phase, vertical motion was strongly observed compared to horizontal motion. (author)

  17. Three-dimensional modelling of sound absorption in porous asphalt pavement for oblique incident waves

    NARCIS (Netherlands)

    Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Glorieux, C.

    2015-01-01

    Sound absorption of porous asphalt pavements is an important property when reducing tyre-road noise. A hybrid model has been developed to predict the sound absorption of porous roads. This model is a combination of an analytical analysis of the sound eld and a numerical approach, including both the

  18. Construction Of Critical Thinking Skills Test Instrument Related The Concept On Sound Wave

    Science.gov (United States)

    Mabruroh, F.; Suhandi, A.

    2017-02-01

    This study aimed to construct test instrument of critical thinking skills of high school students related the concept on sound wave. This research using a mixed methods with sequential exploratory design, consists of: 1) a preliminary study; 2) design and review of test instruments. The form of test instruments in essay questions, consist of 18 questions that was divided into 5 indicators and 8 sub-indicators of the critical thinking skills expressed by Ennis, with questions that are qualitative and contextual. Phases of preliminary study include: a) policy studies; b) survey to the school; c) and literature studies. Phases of the design and review of test instruments consist of two steps, namely a draft design of test instruments include: a) analysis of the depth of teaching materials; b) the selection of indicators and sub-indicators of critical thinking skills; c) analysis of indicators and sub-indicators of critical thinking skills; d) implementation of indicators and sub-indicators of critical thinking skills; and e) making the descriptions about the test instrument. In the next phase of the review test instruments, consist of: a) writing about the test instrument; b) validity test by experts; and c) revision of test instruments based on the validator.

  19. Localization of a sound source in in a guided medium and reverberating field. Contribution to a study on leak localization in the internal wall of containment of a nuclear reactor in the case of a severe reactor accident

    International Nuclear Information System (INIS)

    Thomann, F.

    1996-01-01

    Basic data necessary for the localization of a leak in the internal wall of the containment are presented by studying the sound generated by gas jets coming out of (leaking fissures) as well as propagation in a guided medium. The results acquired have led us to choose the simple intercorrelation method and the matched filed processing method, both of which are likely to adequately handle our problems. Whereas the intercorrelation method appears to be limited in scope when dealing in the guided medium, the matched field processing is suited to leak localization over a surface of approximately 1000 m 2 (for a total surface of 10 000 m 2 ). Preliminary studies on the leak signal and on replicated signals have led us to limit the frequency band to 2600 - 3000 Hz. We have succeeded in locating a leak situated in an ordinary position with a minimum amount of replicated signals and basic data. We have improved on the estimation of Bartlett and MVDE (minimum variance distortion less filter) rendering them even more effective. Afterwards, we considered the severe accident situation and showed that the system can be installed in situ. (author)

  20. A Statistical Analysis of Langmuir Wave-Electron Correlations Observed by the CHARM II Auroral Sounding Rocket

    Science.gov (United States)

    Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

    2014-12-01

    Langmuir-mode electron plasma waves are frequently observed by spacecraft in active plasma environments such as the ionosphere. Ionospheric Langmuir waves may be excited by the bump-on-tail instability generated by impinging beams of electrons traveling parallel to the background magnetic field (B). The Correlation of High-frequencies and Auroral Roar Measurement (CHARM II) sounding rocket was launched into a substorm at 9:49 UT on 17 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the University of Iowa Wave-Particle Correlator (WPC), the Dartmouth High-Frequency Experiment (HFE), several charged particle detectors, low-frequency wave instruments, and a magnetometer. The HFE is a receiver system which effectively yields continuous (100% duty cycle) electric-field waveform measurements from 100 kHz to 5 MHz, and which had its detection axis aligned nominally parallel to B. The HFE output was fed on-payload to the WPC, which uses a phase-locked loop to track the incoming wave frequency with the most power, then sorting incoming electrons at eight energy levels into sixteen wave-phase bins. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, and the WPC showed wave-lock and statistically significant particle correlation distributions during several time periods. We show results of an in-depth analysis of the CHARM II WPC data for the entire flight, including statistical analysis of correlations which show evidence of direct interaction with the Langmuir waves, indicating (at various times) trapping of particles and both driving and damping of Langmuir waves by particles. In particular, the sign of the gradient in particle flux appears to correlate with the phase relation between the electrons and the wave field, with possible implications for the wave physics.

  1. Localizing Submarine Earthquakes by Listening to the Water Reverberations

    Science.gov (United States)

    Castillo, J.; Zhan, Z.; Wu, W.

    2017-12-01

    Mid-Ocean Ridge (MOR) earthquakes generally occur far from any land based station and are of moderate magnitude, making it complicated to detect and in most cases, locate accurately. This limits our understanding of how MOR normal and transform faults move and the manner in which they slip. Different from continental events, seismic records from earthquakes occurring beneath the ocean floor show complex reverberations caused by P-wave energy trapped in the water column that are highly dependent of the source location and the efficiency to which energy propagated to the near-source surface. These later arrivals are commonly considered to be only a nuisance as they might sometimes interfere with the primary arrivals. However, in this study, we take advantage of the wavefield's high sensitivity to small changes in the seafloor topography and the present-day availability of worldwide multi-beam bathymetry to relocate submarine earthquakes by modeling these water column reverberations in teleseismic signals. Using a three-dimensional hybrid method for modeling body wave arrivals, we demonstrate that an accurate hypocentral location of a submarine earthquake (<5 km) can be achieved if the structural complexities near the source region are appropriately accounted for. This presents a novel way of studying earthquake source properties and will serve as a means to explore the influence of physical fault structure on the seismic behavior of transform faults.

  2. Ducted electromagnetic waves in the Martian ionosphere detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar

    Science.gov (United States)

    Zhang, Zhenfei; Orosei, Roberto; Huang, Qian; Zhang, Jie

    2016-07-01

    In the data of the Mars Advanced Radar for Subsurface and Ionosphere Sounding on board the European Space Agency (ESA) mission Mars Express (MEX), a distinctive type of signals (called the "epsilon signature"), which is similar to that previously detected during radio sounding of the terrestrial F region ionosphere, is found. The signature is interpreted to originate from multiple reflections of electromagnetic waves propagating along sounder pulse-created, crustal magnetic field-aligned plasma bubbles (waveguides). The signatures have a low (below 0.5%) occurrence rate and apparent cutoff frequencies 3-5 times higher than the theoretical one for an ordinary mode wave. These properties are explained by the influence of the perpendicular ionospheric plasma density gradient and the sounder pulse frequency on the formation of waveguides.

  3. Usage of measured reverberation tail in a binaural room impulse response synthesis

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Madsen, Esben

    2011-01-01

    The aim of the modern communication technologies is an immersive experience. One of the applications that should provide the feeling of being together and sharing the same environment during the communication process is BEAMING. The goal of this paper is to improve audible spatial impression...... density of reflections. That can lead to metallic and unnatural sound. Also, room-specific sound envelopment feeling is lost. This paper investigates the possibility of using measured reverberation tail instead of the modeled one in BRIRs synthesis. Three cases are observed. In the first one, BRIRs...... case and measured late reverberation from the first one. All three cases are evaluated and compared objectively based on the obtained room acoustic parameters as well as subjectively by listening tests....

  4. Neural Segregation of Concurrent Speech: Effects of Background Noise and Reverberation on Auditory Scene Analysis in the Ventral Cochlear Nucleus.

    Science.gov (United States)

    Sayles, Mark; Stasiak, Arkadiusz; Winter, Ian M

    2016-01-01

    Concurrent complex sounds (e.g., two voices speaking at once) are perceptually disentangled into separate "auditory objects". This neural processing often occurs in the presence of acoustic-signal distortions from noise and reverberation (e.g., in a busy restaurant). A difference in periodicity between sounds is a strong segregation cue under quiet, anechoic conditions. However, noise and reverberation exert differential effects on speech intelligibility under "cocktail-party" listening conditions. Previous neurophysiological studies have concentrated on understanding auditory scene analysis under ideal listening conditions. Here, we examine the effects of noise and reverberation on periodicity-based neural segregation of concurrent vowels /a/ and /i/, in the responses of single units in the guinea-pig ventral cochlear nucleus (VCN): the first processing station of the auditory brain stem. In line with human psychoacoustic data, we find reverberation significantly impairs segregation when vowels have an intonated pitch contour, but not when they are spoken on a monotone. In contrast, noise impairs segregation independent of intonation pattern. These results are informative for models of speech processing under ecologically valid listening conditions, where noise and reverberation abound.

  5. Assessing student understanding of sound waves and trigonometric reasoning in a technology-rich, project-enhanced environment

    Science.gov (United States)

    Wilhelm, Jennifer Anne

    This case study examined what student content understanding could occur in an inner city Industrial Electronics classroom located at Tree High School where project-based instruction, enhanced with technology, was implemented for the first time. Students participated in a project implementation unit involving sound waves and trigonometric reasoning. The unit was designed to foster common content learning (via benchmark lessons) by all students in the class, and to help students gain a deeper conceptual understanding of a sub-set of the larger content unit (via group project research). The objective goal of the implementation design unit was to have students gain conceptual understanding of sound waves, such as what actually waves in a wave, how waves interfere with one another, and what affects the speed of a wave. This design unit also intended for students to develop trigonometric reasoning associated with sinusoidal curves and superposition of sinusoidal waves. Project criteria within this design included implementation features, such as the need for the student to have a driving research question and focus, the need for benchmark lessons to help foster and scaffold content knowledge and understanding, and the need for project milestones to complete throughout the implementation unit to allow students the time for feedback and revision. The Industrial Electronics class at Tree High School consisted of nine students who met daily during double class periods giving 100 minutes of class time per day. The class teacher had been teaching for 18 years (mathematics, physics, and computer science). He had a background in engineering and experience teaching at the college level. Benchmark activities during implementation were used to scaffold fundamental ideas and terminology needed to investigate characteristics of sound and waves. Students participating in benchmark activities analyzed motion and musical waveforms using probeware, and explored wave phenomena using waves

  6. Sound wave generation by a spherically symmetric outburst and AGN feedback in galaxy clusters II: impact of thermal conduction.

    Science.gov (United States)

    Tang, Xiaping; Churazov, Eugene

    2018-04-01

    We analyze the impact of thermal conduction on the appearance of a shock-heated gas shell which is produced when a spherically symmetric outburst of a supermassive black hole inflates bubbles of relativistic plasma at the center of a galaxy cluster. The presence of the hot and low-density shell can be used as an ancillary indicator for a high rate of energy release during the outburst, which is required to drive strong shocks into the gas. Here we show that conduction can effectively erase such shell, unless the diffusion of electrons is heavily suppressed. We conclude that a more robust proxy to the energy release rate is the ratio between the shock radius and bubble radius. We also revisited the issue of sound waves dissipation induced by thermal conduction in a scenario, where characteristic wavelength of the sound wave is set by the total energy of the outburst. For a fiducial short outburst model, the dissipation length does not exceed the cooling radius in a typical cluster, provided that the conduction is suppressed by a factor not larger than ˜100. For quasi-continuous energy injection neither the shock-heated shell nor the outgoing sound wave are important and the role of conduction is subdominant.

  7. Nonlinear second- and first-sound wave equations in 3He-4He mixtures

    International Nuclear Information System (INIS)

    Mohazzab, Masoud; Mulders, Norbert

    2000-01-01

    We derive nonlinear Burgers equations for first and second sound in mixtures of 3 He- 4 He, using a reductive perturbation method and obtain expressions for the nonlinear and dissipation coefficients. We further find a diffusion equation for a coupled temperature-concentration mode. The amplitude of first (second) sound generated from second (first) sound in mixtures is also derived. Our derivation includes the dependence of thermodynamical quantities on temperature, pressure, and 3 He concentration, and is valid up to a first order in terms of the isobaric expansion coefficient. We show that close to the λ line the nonlinearity of second sound in mixtures is enhanced as compared with pure 4 He

  8. Emphasis of spatial cues in the temporal fine structure during the rising segments of amplitude-modulated sounds

    Science.gov (United States)

    Dietz, Mathias; Marquardt, Torsten; Salminen, Nelli H.; McAlpine, David

    2013-01-01

    The ability to locate the direction of a target sound in a background of competing sources is critical to the survival of many species and important for human communication. Nevertheless, brain mechanisms that provide for such accurate localization abilities remain poorly understood. In particular, it remains unclear how the auditory brain is able to extract reliable spatial information directly from the source when competing sounds and reflections dominate all but the earliest moments of the sound wave reaching each ear. We developed a stimulus mimicking the mutual relationship of sound amplitude and binaural cues, characteristic to reverberant speech. This stimulus, named amplitude modulated binaural beat, allows for a parametric and isolated change of modulation frequency and phase relations. Employing magnetoencephalography and psychoacoustics it is demonstrated that the auditory brain uses binaural information in the stimulus fine structure only during the rising portion of each modulation cycle, rendering spatial information recoverable in an otherwise unlocalizable sound. The data suggest that amplitude modulation provides a means of “glimpsing” low-frequency spatial cues in a manner that benefits listening in noisy or reverberant environments. PMID:23980161

  9. Single-Channel Blind Estimation of Reverberation Parameters

    DEFF Research Database (Denmark)

    Doire, C.S.J.; Brookes, M. D.; Naylor, P. A.

    2015-01-01

    The reverberation of an acoustic channel can be characterised by two frequency-dependent parameters: the reverberation time and the direct-to-reverberant energy ratio. This paper presents an algorithm for blindly determining these parameters from a single-channel speech signal. The algorithm uses...

  10. Sonar waveforms for reverberation rejection, Part IV: Adaptive processing.

    NARCIS (Netherlands)

    IJsselmuide, S.P. van; Deruaz, L.; Been, R.; Doisy, Y.; Beerens, S.P.

    2002-01-01

    For littoral ASW, reverberation is a big problem and rejection of reverberation is of utmost importance. The influence of the transmitted signal on the signal to reverberation ratio has been presented in three preceding papers. In this paper, the influence of improved signal processing on the

  11. Material sound source localization through headphones

    Science.gov (United States)

    Dunai, Larisa; Peris-Fajarnes, Guillermo; Lengua, Ismael Lengua; Montaña, Ignacio Tortajada

    2012-09-01

    In the present paper a study of sound localization is carried out, considering two different sounds emitted from different hit materials (wood and bongo) as well as a Delta sound. The motivation of this research is to study how humans localize sounds coming from different materials, with the purpose of a future implementation of the acoustic sounds with better localization features in navigation aid systems or training audio-games suited for blind people. Wood and bongo sounds are recorded after hitting two objects made of these materials. Afterwards, they are analysed and processed. On the other hand, the Delta sound (click) is generated by using the Adobe Audition software, considering a frequency of 44.1 kHz. All sounds are analysed and convolved with previously measured non-individual Head-Related Transfer Functions both for an anechoic environment and for an environment with reverberation. The First Choice method is used in this experiment. Subjects are asked to localize the source position of the sound listened through the headphones, by using a graphic user interface. The analyses of the recorded data reveal that no significant differences are obtained either when considering the nature of the sounds (wood, bongo, Delta) or their environmental context (with or without reverberation). The localization accuracies for the anechoic sounds are: wood 90.19%, bongo 92.96% and Delta sound 89.59%, whereas for the sounds with reverberation the results are: wood 90.59%, bongo 92.63% and Delta sound 90.91%. According to these data, we can conclude that even when considering the reverberation effect, the localization accuracy does not significantly increase.

  12. Excitation of short-scale fluctuations by parametric decay of helicon waves into ion-sound and Trivelpiece-Gould waves

    International Nuclear Information System (INIS)

    Lorenz, B; Kraemer, M; Selenin, V L; Aliev, Yu M

    2005-01-01

    The helicon wave field and the excitation of short-scale electrostatic fluctuations in a helicon-produced plasma are closely related as both the helicon wave damping and the fluctuation level are shown to increase with the launched rf power. Correlation methods using electrostatic probes as well as microwave back-scattering at the upper-hybrid resonance are applied to obtain the dispersion relations of the fluctuations in the low-frequency and high-frequency ranges. The frequency and wavenumber spectra measured for all components of the wave vector allow us to identify the fluctuations as ion-sound and Trivelpiece-Gould waves that originate from parametric decay of the helicon pump wave. The growth rates and thresholds inferred from the evolution of the fluctuations in a wide range of helicon plasma parameters are in good agreement with predictions for the parametric decay instability that takes into account realistic damping rates for the decay waves as well as non-vanishing parallel wavenumber of the helicon pump

  13. Power Difference in Spectrum of Sound Radiation before and after Break of Phantom by Piezoelectric Extracorporeal Shock Wave Lithotriptor

    Science.gov (United States)

    Kanai, Hiroshi; Jang, Yun-Seok; Chubachi, Noriyoshi; Tanahashi, Yoshikatsu

    1994-05-01

    This paper investigates the difference in the spectrum of sound radiated before and after the break of a phantom at a focal point of the piezoelectric extracorporeal shock wave lithotriptor (ESWL) in order to identify the break time or to examine whether a calculus exists exactly at the focal point or not. From the preliminary experiments using a piece of chalk as a phantom of a calculus to measure the sound radiated when impact is applied to the chalk by an impact hammer, it is found that the bending vibration component of the vibration is exhibited in the spectrum of sound. However, for small-sized chalk shorter than 3 cm, the peak frequency of the bending vibration is higher than 20 kHz. From the experiments using a piezoeletric ESWL, it is found that there is clear difference in the power spectra among the sound radiated before the break, that radiated just after the break in the breaking process, and that radiated when the chalk does not exist at the focal point of the ESWL. These characteristics will be effective for the examination of the existence of the calculus at the focal point.

  14. Sound excitation at reflection of two electromagnetic waves from dence semibounded plasma

    International Nuclear Information System (INIS)

    Livdan, D.O.; Muratov, V.I.; Shuklin, A.P.

    1988-01-01

    The problem of two electromagnetic waves reflection by semibounded plasma which is nontransparent for each of these waves is solved. The reflection coefficients are obtained for normally incident waves. It is shown that the moduli of the reflection coefficients differ from the unit and this is due to the interaction of the external raiation with the acoustic wave excited in plasma. The energy flux in plasma is calculated

  15. Reverberation Mapping Results from MDM Observatory

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Peterson, B. M.; Pogge, R. W.

    2010-01-01

    Reverberation mapping takes advantage of the presence of a time delay or lag, t, between continuum and emission line flux variations observed through spectroscopic monitoring campaigns to infer the radius of the broad-line region (BLR) and, subsequently, the central black hole mass in type 1 AGNs...

  16. Reverberation Mapping Results from MDM Observatory

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Peterson, B. M.; Pogge, R. W.

    2009-01-01

    We present results from a multi-month reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from around the world. We measure broad line region (BLR) radii and black hole masses for six objects. A velocity-resolved analysis of the H_beta response show...

  17. Perception of Reverberation in Small Rooms

    DEFF Research Database (Denmark)

    Kaplanis, Neofytos; Bech, Søren; Jensen, Søren Holdt

    summarises the current literature following a top-down approach. It identifies the perceptual aspects of reverberation and attempts to establish links to physical measures, focussing on small rooms. Results indicate that the current acoustical metrics often have limited correlation to the perceptual...

  18. Problems in nonlinear acoustics: Scattering of sound by sound, parametric receiving arrays, nonlinear effects in asymmetric sound beams and pulsed finite amplitude sound beams

    Science.gov (United States)

    Hamilton, Mark F.

    1989-08-01

    Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.

  19. Resonant behaviour of MHD waves on magnetic flux tubes. I - Connection formulae at the resonant surfaces. II - Absorption of sound waves by sunspots

    Science.gov (United States)

    Sakurai, Takashi; Goossens, Marcel; Hollweg, Joseph V.

    1991-01-01

    The present method of addressing the resonance problems that emerge in such MHD phenomena as the resonant absorption of waves at the Alfven resonance point avoids solving the fourth-order differential equation of dissipative MHD by recourse to connection formulae across the dissipation layer. In the second part of this investigation, the absorption of solar 5-min oscillations by sunspots is interpreted as the resonant absorption of sounds by a magnetic cylinder. The absorption coefficient is interpreted (1) analytically, under certain simplifying assumptions, and numerically, under more general conditions. The observed absorption coefficient magnitude is explained over suitable parameter ranges.

  20. CFD-DEM Simulation of Propagation of Sound Waves in Fluid Particles Fluidised Medium

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available In this work, speed of sound in 2 phase mixture has been explored using CFD-DEM (Computational Fluid Dynamcis - Discrete Element Modelling. In this method volume averaged Navier Stokes, continuity and energy equations are solved for fluid. Particles are simulated as individual entities; their behaviour is captured by Newton's laws of motion and classical contact mechanics. Particle-fluid interaction is captured using drag laws given in literature. The speed of sound in a medium depends on physical properties. It has been found experimentally that speed of sound drops significantly in 2 phase mixture of fluidised particles because of its increased density relative to gas while maintaining its compressibility. Due to the high rate of heat transfer within 2 phase medium as given in Roy et al. (1990, it has been assumed that the fluidised gas-particle medium is isothermal. The similar phenomenon has been tried to be captured using CFD-DEM numerical simulation. The disturbance is introduced and fundamental frequency in the medium is noted to measure the speed of sound for e.g. organ pipe. It has been found that speed of sound is in agreement with the relationship given in Roy et al. (1990. Their assumption that the system is isothermal also appears to be valid.

  1. Interactive physically-based sound simulation

    Science.gov (United States)

    Raghuvanshi, Nikunj

    behind obstructions, reverberation, scattering from complex geometry and sound focusing. This is enabled by a novel compact representation that takes a thousand times less memory than a direct scheme, thus reducing memory footprints to fit within available main memory. To the best of my knowledge, this is the only technique and system in existence to demonstrate auralization of physical wave-based effects in real-time on large, complex 3D scenes.

  2. Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

    Science.gov (United States)

    Baumgarten, Kathrin; Gerding, Michael; Baumgarten, Gerd; Lübken, Franz-Josef

    2018-01-01

    Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly affected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not adequately implemented in many circulation models. The daylight-capable Rayleigh-Mie-Raman (RMR) lidar at Kühlungsborn (54° N, 12° E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement, which shows a large variability of gravity waves and tides on timescales of days. Using a one-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement period a strong 24 h wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4-8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement period and therefore a strong GW activity. The analysis indicates a further change in wave-wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GWs in general circulation models.

  3. A new definition of boundary point between early reflections and late reverberation in room impulse responses.

    Science.gov (United States)

    Hidaka, Takayuki; Yamada, Yoshinari; Nakagawa, Takehiko

    2007-07-01

    The early reflections in the room impulse response are usually defined as those observed within the initial 80 ms after the arrival of the direct sound, after which time the sound field is called reverberant. This number was chosen from measurements of other functions in a limited number of halls. In order to give an objective foundation to this time separation and to establish a physical indicator for it, a new method is proposed that defines a "transition time t(L)," which is the time at which the energy correlation between the direct plus initial sound and the subsequent decaying sound first achieves a specified low value. For various halls this number is shown and its relevance as a new parameter is discussed.

  4. ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. II. LAGRANGIAN CONSTRAINED ANALYSIS

    International Nuclear Information System (INIS)

    Vasil, Geoffrey M.; Lecoanet, Daniel; Brown, Benjamin P.; Zweibel, Ellen G.; Wood, Toby S.

    2013-01-01

    The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves while retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown et al., which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received attention in atmospheric applications, and more recently in studies of white-dwarf supernova progenitors. We demonstrate that one model conserves energy but the other does not. We use Lagrangian variational methods to extend the energy conserving model to a general equation of state, and dub the resulting equation set the generalized pseudo-incompressible (GPI) model. We show that the GPI equations suitably capture low-frequency phenomena in both convection and radiative zones in stars and other stratified systems, and we provide recommendations for converting low-Mach number codes to this equation set

  5. Simultaneous multi-band channel sounding at mm-Wave frequencies

    DEFF Research Database (Denmark)

    Müller, Robert; Häfner, Stephan; Dupleich, Diego

    2016-01-01

    The vision of multi Gbit/s data rates in future mobile networks requires the change to millimeter wave (mm-Wave) frequencies for increasing bandwidth. As a consequence, new technologies have to be deployed to tackle the drawbacks of higher frequency bands, e.g. increased path loss. Development an...

  6. A study of the electric response of He II at the excitation of second sound waves

    Czech Academy of Sciences Publication Activity Database

    Chagovets, Tymofiy

    2016-01-01

    Roč. 42, č. 3 (2016), s. 230-235 ISSN 1063-777X R&D Projects: GA ČR GP13-03806P Institutional support: RVO:68378271 Keywords : superfluid helium * electric response * second sound * ions in He II Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.804, year: 2016

  7. Modelling absorption in porous asphalt concrete for oblique incident sound waves

    NARCIS (Netherlands)

    Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Sas, P; Moens, D.; Denayer, H.

    2014-01-01

    A numerical model to predict the sound absorption of porous asphalt has been developed. The approach is a combination between a microstructural approach and a finite element approach. The model used to describe the viscothermal properties of the air inside the pores of the asphalt is the low reduced

  8. Persistent flow and third-sound waves in the He-II film

    International Nuclear Information System (INIS)

    Verbeek, H.J.

    1980-01-01

    The author describes experiments performed on persistent film-flow in He-II film. Data obtained using the third-sound technique is presented. The experiments demonstrate unequivocally the reality of persistent currents in the He-II film. (Auth.)

  9. Nonlinear Raman scattering behavior with Langmuir and sound waves coupling in a homogeneous plasma

    International Nuclear Information System (INIS)

    Bonnaud, G.; Pesme, D.; Pellat, R.

    1990-01-01

    By means of wave-coupling simulations, the typical nonlinear evolution of stimulated Raman scattering (SRS) is investigated in a homogeneous sub-quarter-critical plasma for present-day low laser irradiances and kilo-electron-volt electron temperatures. The decrease of the Langmuir energy observed after the SRS growth is found to be basically the result of the electrostatic decay instability (EDI) onset, which generates a high-amplitude ion-acoustic wave. The resulting strong modulation of the plasma density causes a conversion process that transforms the initial one-wave-vector Langmuir wave driven by SRS into a Bloch wave and induces SRS detuning and larger damping. The conditions involved herein have allowed isolation of these processes from the modulational instability; in addition, the Langmuir collapse is found not to occur owing to the high electron temperature

  10. Reaching imaginary places: resonance and reverberation

    Directory of Open Access Journals (Sweden)

    Kristupas Sabolius

    2012-10-01

    Full Text Available Based on Bachelard’s phenomenological take on the temporality of imagination, this paper analyzes a few works by Marcos Lutyens, a contemporary artist. Bachelard offers two concepts that bring about an altered temporality of material imagination: resonance and reverberation. Resonance is a dynamical condition through which the world discloses its imaginary opportunities: it oscillates with larger amplitude at some frequencies than it does at others. Under this intense state, the attunement of two rhythms, the rhythm of consciousness and the world-rhythm, can occur. Reverberation technically means a further step, i.e., a change in the configuration of our rhythmical settings through the intrusion of an alien vibration: we are possessed by external rhythms; the so-called depth of our interiority is affected by an alien energy, and we vibrate in tune with alien rhythms. By reshaping the rhythmical organization of one’s perception (using hypnosis, a trance state and registered body automatisms, Lutyens tries to trace pathways related to unconscious thought processes. Shifting the experience of duration, he moves through imaginary environments within the preconscious that are progressively charted and recorded. Consequently it appears that what is “penetration” in space is marked by resonance and reverberation in time.

  11. Binaural segregation in multisource reverberant environments.

    Science.gov (United States)

    Roman, Nicoleta; Srinivasan, Soundararajan; Wang, DeLiang

    2006-12-01

    In a natural environment, speech signals are degraded by both reverberation and concurrent noise sources. While human listening is robust under these conditions using only two ears, current two-microphone algorithms perform poorly. The psychological process of figure-ground segregation suggests that the target signal is perceived as a foreground while the remaining stimuli are perceived as a background. Accordingly, the goal is to estimate an ideal time-frequency (T-F) binary mask, which selects the target if it is stronger than the interference in a local T-F unit. In this paper, a binaural segregation system that extracts the reverberant target signal from multisource reverberant mixtures by utilizing only the location information of target source is proposed. The proposed system combines target cancellation through adaptive filtering and a binary decision rule to estimate the ideal T-F binary mask. The main observation in this work is that the target attenuation in a T-F unit resulting from adaptive filtering is correlated with the relative strength of target to mixture. A comprehensive evaluation shows that the proposed system results in large SNR gains. In addition, comparisons using SNR as well as automatic speech recognition measures show that this system outperforms standard two-microphone beamforming approaches and a recent binaural processor.

  12. Distinguishing Alfven waves from quasi-static field structures associated with the discrete aurora: Sounding rocket and HILAT satellite measurements

    International Nuclear Information System (INIS)

    Knudsen, D.J.; Kelley, M.C.; Earle, G.D.; Vickrey, J.F.; Boehm, M.

    1990-01-01

    The authors present and analyze sounding rocket and HILAT satellite measurements of the low frequency ( 0 in the auroral oval. By examining the time-domain field data it is often difficult to distinguish temporal fluctuations from static structures which are Doppler shifted to a non-zero frequency in the spacecraft frame. However, they show that such a distinction can be made by constructing the impedance function Z(f). Using Z(f) they find agreement with the static field interpretation below about 0.1 Hz in the spacecraft frame, i.e. Z(f) = Σ p -1 where Σ p is the height-integrated Pedersen conductivity of the ionosphere. About 0.1 Hz the authors find Z(f) > Σ p -1 , which they argue to be due to the presence of Alfven waves incident from the magnetosphere and reflecting from the lower ionosphere, forming a standing wave pattern. These waves may represent an electromagnetic coupling mechanism between the auroral acceleration region and the ionosphere

  13. Smart Sound Processing for Defect Sizing in Pipelines Using EMAT Actuator Based Multi-Frequency Lamb Waves

    Directory of Open Access Journals (Sweden)

    Joaquín García-Gómez

    2018-03-01

    Full Text Available Pipeline inspection is a topic of particular interest to the companies. Especially important is the defect sizing, which allows them to avoid subsequent costly repairs in their equipment. A solution for this issue is using ultrasonic waves sensed through Electro-Magnetic Acoustic Transducer (EMAT actuators. The main advantage of this technology is the absence of the need to have direct contact with the surface of the material under investigation, which must be a conductive one. Specifically interesting is the meander-line-coil based Lamb wave generation, since the directivity of the waves allows a study based in the circumferential wrap-around received signal. However, the variety of defect sizes changes the behavior of the signal when it passes through the pipeline. Because of that, it is necessary to apply advanced techniques based on Smart Sound Processing (SSP. These methods involve extracting useful information from the signals sensed with EMAT at different frequencies to obtain nonlinear estimations of the depth of the defect, and to select the features that better estimate the profile of the pipeline. The proposed technique has been tested using both simulated and real signals in steel pipelines, obtaining good results in terms of Root Mean Square Error (RMSE.

  14. Smart Sound Processing for Defect Sizing in Pipelines Using EMAT Actuator Based Multi-Frequency Lamb Waves.

    Science.gov (United States)

    García-Gómez, Joaquín; Gil-Pita, Roberto; Rosa-Zurera, Manuel; Romero-Camacho, Antonio; Jiménez-Garrido, Jesús Antonio; García-Benavides, Víctor

    2018-03-07

    Pipeline inspection is a topic of particular interest to the companies. Especially important is the defect sizing, which allows them to avoid subsequent costly repairs in their equipment. A solution for this issue is using ultrasonic waves sensed through Electro-Magnetic Acoustic Transducer (EMAT) actuators. The main advantage of this technology is the absence of the need to have direct contact with the surface of the material under investigation, which must be a conductive one. Specifically interesting is the meander-line-coil based Lamb wave generation, since the directivity of the waves allows a study based in the circumferential wrap-around received signal. However, the variety of defect sizes changes the behavior of the signal when it passes through the pipeline. Because of that, it is necessary to apply advanced techniques based on Smart Sound Processing (SSP). These methods involve extracting useful information from the signals sensed with EMAT at different frequencies to obtain nonlinear estimations of the depth of the defect, and to select the features that better estimate the profile of the pipeline. The proposed technique has been tested using both simulated and real signals in steel pipelines, obtaining good results in terms of Root Mean Square Error (RMSE).

  15. Sound a very short introduction

    CERN Document Server

    Goldsmith, Mike

    2015-01-01

    Sound is integral to how we experience the world, in the form of noise as well as music. But what is sound? What is the physical basis of pitch and harmony? And how are sound waves exploited in musical instruments? Sound: A Very Short Introduction looks at the science of sound and the behaviour of sound waves with their different frequencies. It also explores sound in different contexts, covering the audible and inaudible, sound underground and underwater, acoustic and electronic sound, and hearing in humans and animals. It concludes with the problem of sound out of place—noise and its reduction.

  16. The Sound of Science

    Science.gov (United States)

    Merwade, Venkatesh; Eichinger, David; Harriger, Bradley; Doherty, Erin; Habben, Ryan

    2014-01-01

    While the science of sound can be taught by explaining the concept of sound waves and vibrations, the authors of this article focused their efforts on creating a more engaging way to teach the science of sound--through engineering design. In this article they share the experience of teaching sound to third graders through an engineering challenge…

  17. Sound power radiated by sources in diffuse fields

    DEFF Research Database (Denmark)

    Polack, Jean-Dominique

    2000-01-01

    Sound power radiated by sources at low frequency notoriously depends on source position. We sampled the sound field of a rectangular room at 18 microphone and 4 source positions. Average power spectra were extrapolated from the reverberant field, taking into account the frequency dependent...

  18. Wave motion as inquiry the physics and applications of light and sound

    CERN Document Server

    Espinoza, Fernando

    2017-01-01

    This undergraduate textbook on the physics of wave motion in optics and acoustics avoids presenting the topic abstractly in order to emphasize real-world examples. While providing the needed scientific context, Dr. Espinoza also relies on students' own experience to guide their learning. The book's exercises and labs strongly emphasize this inquiry-based approach. A strength of inquiry-based courses is that the students maintain a higher level of engagement when they are studying a topic that they have an internal motivation to know, rather than solely following the directives of a professor. "Wave Motion" takes those threads of engagement and interest and weaves them into a coherent picture of wave phenomena. It demystifies key components of life around us--in music, in technology, and indeed in everything we perceive--even for those without a strong math background, who might otherwise have trouble approaching the subject matter.

  19. Propagation of sound and thermal waves in an ionizing-recombining hydrogen plasma: Revision of results

    International Nuclear Information System (INIS)

    Di Sigalotti, Leonardo G.; Sira, Eloy; Tremola, Ciro

    2002-01-01

    The propagation of acoustic and thermal waves in a heat conducting, hydrogen plasma, in which photoionization and photorecombination [H + +e - H+hν(χ)] processes are progressing, is re-examined here using linear analysis. The resulting dispersion equation is solved analytically and the results are compared with previous solutions for the same plasma model. In particular, it is found that wave propagation in a slightly and highly ionized hydrogen plasma is affected by crossing between acoustic and thermal modes. At temperatures where the plasma is partially ionized, waves of all frequencies propagate without the occurrence of mode crossing. These results disagree with those reported in previous work, thereby leading to a different physical interpretation of the propagation of small linear disturbances in a conducting, ionizing-recombining, hydrogen plasma

  20. Sound Design in Virtual Reality Concert Experiences using a Wave Field Synthesis Approach

    DEFF Research Database (Denmark)

    Lind, Rasmus Bloustrød; Milesen, Victor; Smed, Dina Madsen

    2017-01-01

    In this paper we propose an experiment that evaluates the influence of audience noise on the feeling of presence and the perceived quality in a virtual reality concert experience delivered using Wave Field Synthesis. A 360 degree video of a live rock concert from a local band was recorded. Single...

  1. Separation of zeros for source signature identification under reverberant path conditions.

    Science.gov (United States)

    Hasegawa, Tomomi; Tohyama, Mikio

    2011-10-01

    This paper presents an approach to distinguishing the zeros representing a sound source from those representing the transfer function on the basis of Lyon's residue-sign model. In machinery noise diagnostics, the source signature must be separated from observation records under reverberant path conditions. In numerical examples and an experimental piano-string vibration analysis, the modal responses could be synthesized by using clustered line-spectrum modeling. The modeling error represented the source signature subject to the source characteristics being given by a finite impulse response. The modeling error can be interpreted as a remainder function necessary for the zeros representing the source signature. © 2011 Acoustical Society of America

  2. Blind estimation of the number of speech source in reverberant multisource scenarios based on binaural signals

    DEFF Research Database (Denmark)

    May, Tobias; van de Par, Steven

    2012-01-01

    In this paper we present a new approach for estimating the number of active speech sources in the presence of interfering noise sources and reverberation. First, a binaural front-end is used to detect the spatial positions of all active sound sources, resulting in a binary mask for each candidate...... on a support vector machine (SVM) classifier. A systematic analysis shows that the proposed algorithm is able to blindly determine the number and the corresponding spatial positions of speech sources in multisource scenarios and generalizes well to unknown acoustic conditions...

  3. variation of reverberation time with quantity of absorbers in an ...

    African Journals Online (AJOL)

    DJFLEX

    broadcasting and recording studios, reverberation time can be simply controlled to achieve desired results. KEY WORDS: ..... Positions and Actual sizes and Numbers of. Absorbers Used. Measured. Reverberation. Times (s). Calculated with. Sabine Formula. Calculated with. Arau-Puchades. Formula. 500. (Hz). 1000. (Hz).

  4. A two-channel wave analyser for sounding rockets and satellites

    International Nuclear Information System (INIS)

    Brondz, E.

    1989-04-01

    Studies of low frequency electromagnetic waves, produced originally by lightning discharges penetrating the ionosphere, provide an important source of valuable information about the earth's surrounding plasma. Use of rockets and satellites supported by ground-based observations implies, unique opportunity for measuring in situ a number of parameters simultaneously in order to correlate data from various measurements. However, every rocket experiment has to be designed bearing in mind telemetry limitations and/or short flight duration. Typical flight duration for Norwegian rockets launched from Andoeya Rocket Range is 500 to 600 s. Therefore, the most desired way to use a rocket or satellite is to carry out data analyses on board in real time. Recent achievements in Digital Signal Processing (DSP) technology have made it possible to undertake very complex on board data manipulation. As a part of rocket instrumentation, a DSP based unit able to carry out on board analyses of low frequency electromagnetic waves in the ionosphere has been designed. The unit can be seen as a general purpose computer built on the basis of a fixed-point 16 bit signal processor. The unit is supplied with a program code in order to perform wave analyses on two independent channels simultaneously. The analyser is able to perform 256 point complex fast fourier transformations, and it produce a spectral power desity estimate on both channels every 85 ms. The design and construction of the DSP based unit is described and results from the tests are presented

  5. Effects of virtual speaker density and room reverberation on spatiotemporal thresholds of audio-visual motion coherence.

    Directory of Open Access Journals (Sweden)

    Narayan Sankaran

    Full Text Available The present study examined the effects of spatial sound-source density and reverberation on the spatiotemporal window for audio-visual motion coherence. Three different acoustic stimuli were generated in Virtual Auditory Space: two acoustically "dry" stimuli via the measurement of anechoic head-related impulse responses recorded at either 1° or 5° spatial intervals (Experiment 1, and a reverberant stimulus rendered from binaural room impulse responses recorded at 5° intervals in situ in order to capture reverberant acoustics in addition to head-related cues (Experiment 2. A moving visual stimulus with invariant localization cues was generated by sequentially activating LED's along the same radial path as the virtual auditory motion. Stimuli were presented at 25°/s, 50°/s and 100°/s with a random spatial offset between audition and vision. In a 2AFC task, subjects made a judgment of the leading modality (auditory or visual. No significant differences were observed in the spatial threshold based on the point of subjective equivalence (PSE or the slope of psychometric functions (β across all three acoustic conditions. Additionally, both the PSE and β did not significantly differ across velocity, suggesting a fixed spatial window of audio-visual separation. Findings suggest that there was no loss in spatial information accompanying the reduction in spatial cues and reverberation levels tested, and establish a perceptual measure for assessing the veracity of motion generated from discrete locations and in echoic environments.

  6. The stability of second sound waves in a rotating Darcy–Brinkman porous layer in local thermal non-equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    Eltayeb, I A; Elbashir, T B A, E-mail: ieltayeb@squ.edu.om, E-mail: elbashir@squ.edu.om [Department of Mathematics and Statistics, College of Science, Sultan Qaboos University, Muscat 123 (Oman)

    2017-08-15

    The linear and nonlinear stabilities of second sound waves in a rotating porous Darcy–Brinkman layer in local thermal non-equilibrium are studied when the heat flux in the solid obeys the Cattaneo law. The simultaneous action of the Brinkman effect (effective viscosity) and rotation is shown to destabilise the layer, as compared to either of them acting alone, for both stationary and overstable modes. The effective viscosity tends to favour overstable modes while rotation tends to favour stationary convection. Rapid rotation invokes a negative viscosity effect that suppresses the stabilising effect of porosity so that the stability characteristics resemble those of the classical rotating Benard layer. A formal weakly nonlinear analysis yields evolution equations of the Landau–Stuart type governing the slow time development of the amplitudes of the unstable waves. The equilibrium points of the evolution equations are analysed and the overall development of the amplitudes is examined. Both overstable and stationary modes can exhibit supercritical stability; supercritical instability, subcritical instability and stability are not possible. The dependence of the supercritical stability on the relative values of the six dimensionless parameters representing thermal non-equilibrium, rotation, porosity, relaxation time, thermal diffusivities and Brinkman effect is illustrated as regions in regime diagrams in the parameter space. The dependence of the heat transfer and the mean heat flux on the parameters of the problem is also discussed. (paper)

  7. Reading drift in flow rate sensors caused by steady sound waves; Desvios de leitura em sensores de vazao provocados por ondas sonoras estacionarias

    Energy Technology Data Exchange (ETDEWEB)

    Maximiano, Celso; Nieble, Marcio D. [Coordenadoria para Projetos Especiais (COPESP), Sao Paulo, SP (Brazil); Migliavacca, Sylvana C.P.; Silva, Eduardo R.F. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1995-12-31

    The use of thermal sensors very common for the measurement of small flows of gases. In this kind of sensor a little tube forming a bypass is heated symmetrically, then the temperature distribution in the tube modifies with the mass flow along it. When a stationary wave appears in the principal tube it causes an oscillation of pressure around the average value. The sensor, located between two points of the principal tube, indicates not only the principal mass flow, but also that one caused by the difference of pressure induced by the sound wave. When the gas flows at low pressures the equipment indicates a value that do not correspond to the real. Tests and essays were realized by generating a sound wave in the principal tube, without mass flow, and the sensor detected flux. In order to solve this problem a wave-damper was constructed, installed and tested in the system and it worked satisfactory eliminating with efficiency the sound wave. (author). 2 refs., 3 figs.

  8. Investigations on stone fragmentation in different extracorporeal shock wave lithotripsy sound fields in vitro

    Science.gov (United States)

    Dreyer, Thomas; Liebler, Marko; Riedlinger, Rainer

    2005-04-01

    The mechanism of stone fragmentation in ESWL applications is still under investigation. Devices showing a wide focal area and comparably low focal pressure amplitudes have been reported to disintegrate stones more efficiently as current clinical devices with high amplitudes and small focal areas. From this the question is raised whether the underlying different physical mechanisms or treatment issues, like stone localization and movement, are responsible for these results. In this paper fragmentation experiments in vitro with different stone types (e.g., HMT and BegoStone, 15 mm diam.) under different sound fields are presented. A self focusing piezoelectric transducer with a small focal area and peak pressure amplitudes of up to 125 MPa is used. The number of pulses was counted until a complete fragmentation through a 2 mm wire mesh is reached. In order to simulate wide-focus low-pressure conditions, the stones were placed in the prefocal region. Fragmentation results are compared to the case of focal placement. Initial breakage occurs earlier in the prefocal region for the HMT stones, whereas complete fragmentation is reached significantly earlier in the focus for all stone types.

  9. Second Sound

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 6. Second Sound - The Role of Elastic Waves. R Srinivasan. General Article Volume 4 Issue 6 June 1999 pp 15-19. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/004/06/0015-0019 ...

  10. The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility

    Science.gov (United States)

    Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  11. Localization of a sound source in in a guided medium and reverberating field. Contribution to a study on leak localization in the internal wall of containment of a nuclear reactor in the case of a severe reactor accident; Localisation d`une source acoustique en milieu guide et champ reverberant. Contribution a l`etude sur la localisation de fuite de l`enceinte de confinement d`une centrale nucleaire en situation accidentelle grave

    Energy Technology Data Exchange (ETDEWEB)

    Thomann, F

    1996-11-28

    Basic data necessary for the localization of a leak in the internal wall of the containment are presented by studying the sound generated by gas jets coming out of (leaking fissures) as well as propagation in a guided medium. The results acquired have led us to choose the simple intercorrelation method and the matched filed processing method, both of which are likely to adequately handle our problems. Whereas the intercorrelation method appears to be limited in scope when dealing in the guided medium, the matched field processing is suited to leak localization over a surface of approximately 1000 m{sup 2} (for a total surface of 10 000 m{sup 2}). Preliminary studies on the leak signal and on replicated signals have led us to limit the frequency band to 2600 - 3000 Hz. We have succeeded in locating a leak situated in an ordinary position with a minimum amount of replicated signals and basic data. We have improved on the estimation of Bartlett and MVDE (minimum variance distortion less filter) rendering them even more effective. Afterwards, we considered the severe accident situation and showed that the system can be installed in situ. (author) 88 refs.

  12. Spatial selective auditory attention in the presence of reverberant energy: individual differences in normal-hearing listeners.

    Science.gov (United States)

    Ruggles, Dorea; Shinn-Cunningham, Barbara

    2011-06-01

    Listeners can selectively attend to a desired target by directing attention to known target source features, such as location or pitch. Reverberation, however, reduces the reliability of the cues that allow a target source to be segregated and selected from a sound mixture. Given this, it is likely that reverberant energy interferes with selective auditory attention. Anecdotal reports suggest that the ability to focus spatial auditory attention degrades even with early aging, yet there is little evidence that middle-aged listeners have behavioral deficits on tasks requiring selective auditory attention. The current study was designed to look for individual differences in selective attention ability and to see if any such differences correlate with age. Normal-hearing adults, ranging in age from 18 to 55 years, were asked to report a stream of digits located directly ahead in a simulated rectangular room. Simultaneous, competing masker digit streams were simulated at locations 15° left and right of center. The level of reverberation was varied to alter task difficulty by interfering with localization cues (increasing localization blur). Overall, performance was best in the anechoic condition and worst in the high-reverberation condition. Listeners nearly always reported a digit from one of the three competing streams, showing that reverberation did not render the digits unintelligible. Importantly, inter-subject differences were extremely large. These differences, however, were not significantly correlated with age, memory span, or hearing status. These results show that listeners with audiometrically normal pure tone thresholds differ in their ability to selectively attend to a desired source, a task important in everyday communication. Further work is necessary to determine if these differences arise from differences in peripheral auditory function or in more central function.

  13. Room acoustic simulation system considered wave motion chacteristic; Hadosei wo koryoshita shitsunai onba simulation system

    Energy Technology Data Exchange (ETDEWEB)

    Tsuboi, M.; Watanabe, M.; Hirano, S. [Obayashi Corp., Osaka (Japan). Technical Research Inst.

    1996-03-20

    A practical calculating method is developed, which includes data of all audible frequencies used as the basic data for visible and audible acoustic evaluation of the sound field for supporting acoustic designing, and can calculate long term impulse responses covering those of reverberation. By the face integration method which performs calculation by dividing the responses from the face elements, at each sound input to the boundary surface, into geometrical wave components and scattered wave components, it is shown that long time impulse response can be calculated with no need for drastic increase in the calculating time. No extreme deterioration of the accuracy is observed even when the face elements are divided roughly, and the method can be applied to response calculation even in a limited time with less divided number of the wave face elements for certain items to be investigated. Sound field is visualized by three dimensional image sound source distribution in which the frequency characteristics of the initial reflected sound are displayed in color, and a series of systems are developed which enable virtual experience of estimated sound field with three dimensional spread by binaural hearing based on OSS (orthostereophonic system). 9 refs., 8 figs.

  14. Reverberation time in class rooms – Comparison of regulations and classification criteria in the Nordic countries

    DEFF Research Database (Denmark)

    Rasmussen, Birgit; Brunskog, Jonas; Hoffmeyer, Dan

    2012-01-01

    Regulatory requirements or guidelines for classroom reverberation time exist in all five Nordic countries and in most of Europe – as well as other acoustic criteria for schools, e.g. concerning airborne and impact sound insulation, facade sound insulation and installation noise. There are several...... reasons for having such requirements: Improving learning efficiency for pupils and work conditions for teachers and reducing noise levels, thus increasing comfort for everyone. Instead of including acoustic regulatory requirements for schools directly in the building regulations, Iceland, Norway...... and Sweden have introduced acoustic quality classes A, B, C and D in national standards with class C referred to as regulatory requirements. These national classification standards are dealing with acoustic classes for several types of buildings. A classification scheme also exists in Finland...

  15. Effects of hearing-aid dynamic range compression on spatial perception in a reverberant environment

    DEFF Research Database (Denmark)

    Hassager, Henrik Gert; Wiinberg, Alan; Dau, Torsten

    2017-01-01

    This study investigated the effects of fast-acting hearing-aid compression on normal-hearing and hearing-impaired listeners’ spatial perception in a reverberant environment. Three compression schemes—independent compression at each ear, linked compression between the two ears, and “spatially ideal......” compression operating solely on the dry source signal—were considered using virtualized speech and noise bursts. Listeners indicated the location and extent of their perceived sound images on the horizontal plane. Linear processing was considered as the reference condition. The results showed that both...... independent and linked compression resulted in more diffuse and broader sound images as well as internalization and image splits, whereby more image splits were reported for the noise bursts than for speech. Only the spatially ideal compression provided the listeners with a spatial percept similar...

  16. Seismic and Biological Sources of Ambient Ocean Sound

    Science.gov (United States)

    Freeman, Simon Eric

    Sound is the most efficient radiation in the ocean. Sounds of seismic and biological origin contain information regarding the underlying processes that created them. A single hydrophone records summary time-frequency information from the volume within acoustic range. Beamforming using a hydrophone array additionally produces azimuthal estimates of sound sources. A two-dimensional array and acoustic focusing produce an unambiguous two-dimensional `image' of sources. This dissertation describes the application of these techniques in three cases. The first utilizes hydrophone arrays to investigate T-phases (water-borne seismic waves) in the Philippine Sea. Ninety T-phases were recorded over a 12-day period, implying a greater number of seismic events occur than are detected by terrestrial seismic monitoring in the region. Observation of an azimuthally migrating T-phase suggests that reverberation of such sounds from bathymetric features can occur over megameter scales. In the second case, single hydrophone recordings from coral reefs in the Line Islands archipelago reveal that local ambient reef sound is spectrally similar to sounds produced by small, hard-shelled benthic invertebrates in captivity. Time-lapse photography of the reef reveals an increase in benthic invertebrate activity at sundown, consistent with an increase in sound level. The dominant acoustic phenomenon on these reefs may thus originate from the interaction between a large number of small invertebrates and the substrate. Such sounds could be used to take census of hard-shelled benthic invertebrates that are otherwise extremely difficult to survey. A two-dimensional `map' of sound production over a coral reef in the Hawaiian Islands was obtained using two-dimensional hydrophone array in the third case. Heterogeneously distributed bio-acoustic sources were generally co-located with rocky reef areas. Acoustically dominant snapping shrimp were largely restricted to one location within the area surveyed

  17. Nuclear sound

    International Nuclear Information System (INIS)

    Wambach, J.

    1991-01-01

    Nuclei, like more familiar mechanical systems, undergo simple vibrational motion. Among these vibrations, sound modes are of particular interest since they reveal important information on the effective interactions among the constituents and, through extrapolation, on the bulk behaviour of nuclear and neutron matter. Sound wave propagation in nuclei shows strong quantum effects familiar from other quantum systems. Microscopic theory suggests that the restoring forces are caused by the complex structure of the many-Fermion wavefunction and, in some cases, have no classical analogue. The damping of the vibrational amplitude is strongly influenced by phase coherence among the particles participating in the motion. (author)

  18. Modeling of Reverberation Effects for Radio Localization and Communications

    DEFF Research Database (Denmark)

    Steinböck, Gerhard

    2013-01-01

    a recently proposed approach, we transcribe these models to electromagnetics and validate them experimentally following a systematic procedure. These transcribed models provide accurate predictions of the delay power spectrum in a typical office environment. Furthermore, they can predict changes...... into a distance dependent model of the delay power spectrum, which we then validate experimentally. From this model we derive secondary models that predict the received power, the mean delay, the rms delay spread and the kurtosis versus distance. The behavior of the diffuse component versus distance in indoor...... environment is linked to reverberation effects analog to reverberation effects observed in room acoustics and electromagnetic reverberation chambers. Reverberation models of room acoustics relate the decay rate of the diffuse component to the room geometry and an average absorption coefficient. Following...

  19. An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field

    DEFF Research Database (Denmark)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn

    2014-01-01

    This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and sub...

  20. A survey of elementary plasma instabilities and ECH wave noise properties relevant to plasma sounding by means of particle in cell simulations

    International Nuclear Information System (INIS)

    Dieckmann, M.E.

    1999-01-01

    In this work the emission of high amplitude wave packets into a plasma is examined. The plasma is modelled by an 1 1/2D electromagnetic and relativistic particle in cell code. The antenna is modelled by applying forced electrostatic field oscillations to a subset of the simulation grid cells. The emitted wave packets are followed in space and time. It is investigated how the wave packets are affected by instabilities. The detected instabilities affecting ECH waves have been identified as wave decay, nonlinear damping due to trapping and modulational instabilities. These instabilities have been discussed with hindsight to the plasma sounding experiment. A plasma sounder is an experiment emitting short wave packets into the ambient plasma and then it listens to the response. The assumption that the emitted waves are linear waves then allows to determine the plasma magnetic field strength, the electron density and possibly the electron thermal velocity from the response spectrum. The impact of the non-linear instabilities on the plasma wave response spectrum provided by a sounder have been predicted in this work and the predictions have been shown to match a wide range of experimental observations. A dependence of the instabilities on the simulation noise levels, for example the dependence of the wave interaction time in a wave decay on the noise electric field amplitudes, required it to investigate the simulation noise properties (spectral distribution) and to compare it to real plasma thermal noise. It has also been examined how a finite length antenna would filter the simulation noise. (author)

  1. Separation of radiated sound field components from waves scattered by a source under non-anechoic conditions

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn

    2010-01-01

    to the source. Thus the radiated free-field component is estimated simultaneously with solving the inverse problem of reconstructing the sound field near the source. The method is particularly suited to cases in which the overall contribution of reflected sound in the measurement plane is significant....

  2. Moderately reverberant learning ultrasonic pinch panel.

    Science.gov (United States)

    Nikolovski, Jean-Pierre

    2013-10-01

    Tactile sensing is widely used in human-computer interfaces. However, mechanical integration of touch technologies is often perceived as difficult by engineers because it often limits the freedom of style or form factor requested by designers. Recent work in active ultrasonic touch technologies has made it possible to transform thin glass plates, metallic sheets, or plastic shells into interactive surfaces. The method is based on a learning process of touch-induced, amplitude-disturbed diffraction patterns. This paper proposes, first, an evolution in the design with multiple dipole transducers that improves touch sensitivity or maximum panel size by a factor of ten, and improves robustness and usability in moderately reverberant panels, and second, defines a set of acoustic variables in the signal processing for the evaluation of sensitivity and radiating features. For proof of concept purposes, the design and process are applied to 3.2- and 6-mm-thick glass plates with variable damping conditions. Transducers are bonded to only one short side of the rectangular substrates. Measurements show that the highly sensitive free lateral sides are perfectly adapted for pinch-touch and pinch-slide interactions. The advantage of relative versus absolute touch disturbance measurement is discussed, together with tolerance to abutting contaminants.

  3. Reverberation Mapping of High-Luminosity Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Kaspi, Shai [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv (Israel); Brandt, William N. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA (United States); Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA (United States); Department of Physics, Pennsylvania State University, University Park, PA (United States); Maoz, Dan; Netzer, Hagai [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv (Israel); Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA (United States); Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA (United States); Shemmer, Ohad, E-mail: shai@wise.tau.ac.il [Department of Physics, University of North Texas, Denton, TX (United States)

    2017-10-30

    Over the past three decades reverberation mapping (RM) has been applied to about 100 AGNs. Their broad line region (BLR) sizes were measured and yielded mass estimates of the black holes in their center. However, very few attempts were carried out for high-luminosity quasars, at luminosities higher than 10{sup 46} erg/sec in the optical. Most of these attempts failed since RM of such quasars is difficult due to a number of reasons, mostly due to the long time needed to monitor these objects. During the past two decades we carried out a RM campaign on six high-luminosity quasars. This contribution presents some of the final light curves of that RM campaign in which we measured the BLR size in C iv of three of the objects (S5 0836+71, SBS 1116+603, and SBS 1425+606). We present the C iv BLR size and luminosity relation over eight orders of magnitude in luminosity, pushing the luminosity limit to its highest point so far.

  4. Radio-Wave Tomography of Inhomogeneities in Biological Media with Multi-Frequency Sounding in the Range 2-8 GHZ

    Directory of Open Access Journals (Sweden)

    Shipilov Sergey

    2018-01-01

    Full Text Available In this paper, a method for detecting and mapping inhomogeneities in biological tissues using the radio-wave tomosynthesis method is presented. The proposed method of radio-wave tomosynthesis allows us to calculate the three-dimensional distribution of the permittivity of the space under study and, thereby, to detect tissue inhomogeneities and to determine their location and size. Due to their harmlessness for humans, these methods are suitable for dynamic observation of changes in the size of formation, in contrast to x-ray methods, for which regular doses of ionizing radiation are contraindicated. Therefore, the development of non-invasive methods for the search for inhomogeneities in biological media based on radio-wave sounding, which makes it possible to identify pathological formations, is now very relevant.

  5. Exploiting Deep Neural Networks and Head Movements for Robust Binaural Localization of Multiple Sources in Reverberant Environments

    DEFF Research Database (Denmark)

    Ma, Ning; May, Tobias; Brown, Guy J.

    2017-01-01

    This paper presents a novel machine-hearing system that exploits deep neural networks (DNNs) and head movements for robust binaural localization of multiple sources in reverberant environments. DNNs are used to learn the relationship between the source azimuth and binaural cues, consisting...... of the complete cross-correlation function (CCF) and interaural level differences (ILDs). In contrast to many previous binaural hearing systems, the proposed approach is not restricted to localization of sound sources in the frontal hemifield. Due to the similarity of binaural cues in the frontal and rear...

  6. Revisiting perceptual compensation for effects of reverberation in speech identifcation

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Dau, Torsten

    2010-01-01

    Listeners were given the task to identify the stop-consonant [t] in the test-word "stir" when the word was embedded in a carrier sentence. Reverberation was added to the test-word, but not to the carrier, and the ability to identify the [t] decreased because the amplitude modulations associated...... with the [t] were smeared. When a similar amount of reverberation was also added to the carrier sentence, the listeners' ability to identify the stop-consonant was restored. This phenomenon has in previous research been considered as evidence for an extrinsic compensation mechanism for reverberation...... an interference effect that impedes the identification of the stop-consonant. These findings raise doubts about the existence of the compensation mechanism....

  7. Propagation of gravity waves and spread F in the low-latitude ionosphere over Tucumán, Argentina, by continuous Doppler sounding: First results

    Czech Academy of Sciences Publication Activity Database

    Chum, Jaroslav; Bonomi, F. A. M.; Fišer, Jiří; Cabrera, M. A.; Ezquer, R. G.; Burešová, Dalia; Laštovička, Jan; Baše, Jiří; Hruška, František; Molina, M. G.; Ise, J. E.; Cangemi, J. I.; Šindelářová, Tereza

    2014-01-01

    Roč. 119, č. 8 (2014), s. 6954-6965 ISSN 2169-9380 R&D Projects: GA ČR(CZ) GAP209/12/2440; GA ČR GP13-09778P Institutional support: RVO:68378289 Keywords : low latitude ionosphere * Ionospheric irregularities * equatorial spread F * gravity waves * scintillation * remote sensing * Doppler sounding Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.426, year: 2014 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020184/abstract

  8. Diffuse sound field: challenges and misconceptions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    Diffuse sound field is a popular, yet widely misused concept. Although its definition is relatively well established, acousticians use this term for different meanings. The diffuse sound field is defined by a uniform sound pressure distribution (spatial diffusion or homogeneity) and uniform...... tremendously in different chambers because the chambers are non-diffuse in variously different ways. Therefore, good objective measures that can quantify the degree of diffusion and potentially indicate how to fix such problems in reverberation chambers are needed. Acousticians often blend the concept...... of mixing and diffuse sound field. Acousticians often refer diffuse reflections from surfaces to diffuseness in rooms, and vice versa. Subjective aspects of diffuseness have not been much investigated. Finally, ways to realize a diffuse sound field in a finite space are discussed....

  9. Sound Visualization and Holography

    Science.gov (United States)

    Kock, Winston E.

    1975-01-01

    Describes liquid surface holograms including their application to medicine. Discusses interference and diffraction phenomena using sound wave scanning techniques. Compares focussing by zone plate to holographic image development. (GH)

  10. Breaking the Sound Barrier

    Science.gov (United States)

    Brown, Tom; Boehringer, Kim

    2007-01-01

    Students in a fourth-grade class participated in a series of dynamic sound learning centers followed by a dramatic capstone event--an exploration of the amazing Trashcan Whoosh Waves. It's a notoriously difficult subject to teach, but this hands-on, exploratory approach ignited student interest in sound, promoted language acquisition, and built…

  11. The Textile Form of Sound

    DEFF Research Database (Denmark)

    Bendixen, Cecilie

    Sound is a part of architecture, and sound is complex. Upon this, sound is invisible. How is it then possible to design visual objects that interact with the sound? This paper addresses the problem of how to get access to the complexity of sound and how to make textile material revealing the form...... goemetry by analysing the sound pattern at a specific spot. This analysis is done theoretically with algorithmic systems and practical with waves in water. The paper describes the experiments and the findings, and explains how an analysis of sound can be catched in a textile form....

  12. Thermal infrared sounding observations of lower atmospheric variances at Mars and their implications for gravity wave activity: a preliminary examination

    Science.gov (United States)

    Heavens, N. G.

    2017-12-01

    It has been recognized for over two decades that the mesoscale statistical variance observed by Earth-observing satellites at temperature-sensitive frequencies above the instrumental noise floor is a measure of gravity wave activity. These types of observation have been made by a variety of satellite instruments have been an important validation tool for gravity wave parameterizations in global and mesoscale models. At Mars, the importance of topographic and non-topographic sources of gravity waves for the general circulation is now widely recognized and the target of recent modeling efforts. However, despite several ingenious studies, gravity wave activity near hypothetical lower atmospheric sources has been poorly and unsystematically characterized, partly because of the difficulty of separating the gravity wave activity from baroclinic wave activity and the thermal tides. Here will be presented a preliminary analysis of calibrated radiance variance at 15.4 microns (635-665 cm-1) from nadir, off-nadir, and limb observations by the Mars Climate Sounder on board Mars Reconnaissance Orbiter. The overarching methodology follows Wu and Waters (1996, 1997). Nadir, off-nadir, and lowest detector limb observations should sample variability with vertical weighting functions centered high in the lower atmosphere (20-30 km altitude) and full width half maximum (FWHM) 20 km but be sensitive to gravity waves with different horizontal wavelengths and slightly different vertical wavelengths. This work is supported by NASA's Mars Data Analysis Program (NNX14AM32G). References Wu, D.L. and J.W. Waters, 1996, Satellite observations of atmospheric variances: A possible indication of gravity waves, GRL, 23, 3631-3634. Wu D.L. and J.W. Waters, 1997, Observations of Gravity Waves with the UARS Microwave Limb Sounder. In: Hamilton K. (eds) Gravity Wave Processes. NATO ASI Series (Series I: Environmental Change), vol 50. Springer, Berlin, Heidelberg.

  13. Experimental Validation of the Reverberation Effect in Room Electromagnetics

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Pedersen, Troels; Fleury, Bernard Henri

    2015-01-01

    . This tail can be characterized with Sabine's or Eyring's reverberation models, which were initially developed in acoustics. So far, these models were only fitted to data collected from radio measurements, but no thorough validation of their prediction ability in electromagnetics has been performed yet...

  14. Optimizing the stirring strategy for the vibrating intrinsic reverberation chamber

    NARCIS (Netherlands)

    Serra, Ramiro; Serra, Ramiro; Leferink, Frank Bernardus Johannes

    2010-01-01

    This work describes the definition, application and assessment of a factorial plan with the aim of gaining insight on what kind of stirring strategy could work the best in a vibrating intrinsic reverberation chamber. Three different stirring strategies were defined as factors of a factorial

  15. Characteristics and prediction of sound level in extra-large spaces

    OpenAIRE

    Wang, C.; Ma, H.; Wu, Y.; Kang, J.

    2018-01-01

    This paper aims to examine sound fields in extra-large spaces, which are defined in this paper as spaces used by people, with a volume approximately larger than 125,000m 3 and absorption coefficient less than 0.7. In such spaces inhomogeneous reverberant energy caused by uneven early reflections with increasing volume has a significant effect on sound fields. Measurements were conducted in four spaces to examine the attenuation of the total and reverberant energy with increasing source-receiv...

  16. 'Reverberation time', dreaming and the capacity to dream.

    Science.gov (United States)

    Birksted-Breen, Dana

    2009-02-01

    In this paper the author suggests that understanding the roots of the subjective sense of time can throw light on the disturbances in psychic time which are found in particular in the more severe pathologies. She introduces the argument that the roots of the development of the sense of time rest on a primitive sense of time she calls 'reverberation time'. By this notion she refers to the particular quality of the earliest 'back and forth' internalized exchange with the mother in which the auditory dimension plays a significant part. Referring to a wide range of literature and clinical examples, the author thus suggests that the subjective sense of time is created by the reverberation between mother and infant. Disturbances in this area will be reflected in the pathological 'arresting' of time which is observed in the different pathologies and, in particular, around the negotiation of the depressive position and the oedipal situation.Extending this argument, the author goes on to suggest that it is the internalization of this experience of 'reverberation' which lies at the heart of the experience of dreaming; she considers that dreaming understood as an internal dialogue points both to its roots in the relationship to the maternal object and to its fundamental role in psychic life. The author concludes that 'reverberation time' is also the building block of a psychoanalysis, leading to 'unfreezing' psychic time and enabling the reconnection of 'here and now' with 'there and then' in a flexible way which promotes open possibilities, and that this takes place via the analyst's reverie, or time of reverberation.

  17. On the second-order homogenization of wave motion in periodic media and the sound of a chessboard

    Science.gov (United States)

    Wautier, Antoine; Guzina, Bojan B.

    2015-05-01

    The goal of this study is to better understand the mathematical structure and ramifications of the second-order homogenization of low-frequency wave motion in periodic solids. To this end, multiple-scales asymptotic approach is applied to the scalar wave equation (describing anti-plane shear motion) in one and two spatial dimensions. In contrast to previous studies where the second-order homogenization has lead to the introduction of a single fourth-order derivative in the governing equation, present investigation demonstrates that such (asymptotic) approach results in a family of field equations uniting spatial, temporal, and mixed fourth-order derivatives - that jointly control incipient wave dispersion. Given the consequent freedom in selecting the affiliated lengthscale parameters, the notion of an optimal asymptotic model is next considered in a one-dimensional setting via its ability to capture the salient features of wave propagation within the first Brillouin zone, including the onset and magnitude of the phononic band gap. In the context of two-dimensional wave propagation, on the other hand, the asymptotic analysis is first established in a general setting, exposing the constant shear modulus as sufficient condition under which the second-order approximation of a bi-periodic elastic solid is both isotropic and limited to even-order derivatives. On adopting a chessboard-like periodic structure (with contrasts in both modulus and mass density) as a testbed for in-depth analytical treatment, it is next shown that the second-order approximation of germane wave motion is governed by a family fourth-order differential equations that: (i) entail exclusively even-order derivatives and homogenization coefficients that depend explicitly on the contrast in mass density; (ii) describe anisotropic wave dispersion characterized by the "sin4 θ +cos4 θ" term, and (iii) include the asymptotic model for a square lattice of circular inclusions as degenerate case. For

  18. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    Science.gov (United States)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  19. On Spatial Structuring of the F2 Layer Studied by the Satellite Radio Sounding of the Ionosphere Disturbed by High-Power HF Radio Waves

    Science.gov (United States)

    Tereshchenko, E. D.; Turyansky, V. A.; Khudukon, B. Z.; Yurik, R. Yu.; Frolov, V. L.

    2018-01-01

    We present the results of studying the characteristics of the artificial plasma structures excited in the ionospheric F2 region modified by high-power HF radio waves. The experiments were carried out at the Sura heating facility using satellite radio sounding of the ionosphere. The plasma density profile was reconstructed with the highest possible spatial resolution for today, about 4 km. In a direction close to the magnetic zenith of the pump wave, the following phenomena were observed: the formation of a cavity with a 15% lower plasma density at the altitudes of the F2 layer and below; the formation of an area with plasma density increased by 12% at altitudes greater than 400 km. With a long-term quasiperiodic impact of the pump wave on the ionosphere, wavy large-scale electron-density perturbations (the meridional scale λx ≈ 130 km and the vertical scale λz ≈ 440 km) are also formed above the Sura facility. These perturbations can be due to the plasma density modulation by an artificial acoustic-gravity wave with a period of 10.6 m, which was formed by the heat source inside a large-scale cavity with low plasma density; there is generation of the electron density irregularities for the electrons with ΔNe/Ne ≈ 3% in the form of layers having the sizes 10-12 km along and about 24 km across the geomagnetic field, which are found both below and above the F2-layer maximum. The mechanisms of the formation of these plasma structures are discussed.

  20. Effects of noise and reverberation on speech perception and listening comprehension of children and adults in a classroom-like setting.

    Science.gov (United States)

    Klatte, Maria; Lachmann, Thomas; Meis, Markus

    2010-01-01

    The effects of classroom noise and background speech on speech perception, measured by word-to-picture matching, and listening comprehension, measured by execution of oral instructions, were assessed in first- and third-grade children and adults in a classroom-like setting. For speech perception, in addition to noise, reverberation time (RT) was varied by conducting the experiment in two virtual classrooms with mean RT = 0.47 versus RT = 1.1 s. Children were more impaired than adults by background sounds in both speech perception and listening comprehension. Classroom noise evoked a reliable disruption in children's speech perception even under conditions of short reverberation. RT had no effect on speech perception in silence, but evoked a severe increase in the impairments due to background sounds in all age groups. For listening comprehension, impairments due to background sounds were found in the children, stronger for first- than for third-graders, whereas adults were unaffected. Compared to classroom noise, background speech had a smaller effect on speech perception, but a stronger effect on listening comprehension, remaining significant when speech perception was controlled. This indicates that background speech affects higher-order cognitive processes involved in children's comprehension. Children's ratings of the sound-induced disturbance were low overall and uncorrelated to the actual disruption, indicating that the children did not consciously realize the detrimental effects. The present results confirm earlier findings on the substantial impact of noise and reverberation on children's speech perception, and extend these to classroom-like environmental settings and listening demands closely resembling those faced by children at school.

  1. Sound algorithms

    OpenAIRE

    De Götzen , Amalia; Mion , Luca; Tache , Olivier

    2007-01-01

    International audience; We call sound algorithms the categories of algorithms that deal with digital sound signal. Sound algorithms appeared in the very infancy of computer. Sound algorithms present strong specificities that are the consequence of two dual considerations: the properties of the digital sound signal itself and its uses, and the properties of auditory perception.

  2. Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Fausnaugh, M. M.; Denney, K. D.; Peterson, B. M.; Kochanek, C. S.; Pogge, R. W.; Brown, Jonathan S.; Coker, C. T. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); Grier, C. J.; Beatty, Thomas G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Rosa, G. De [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Adams, S. M. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Barth, A. J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bhattacharjee, A.; Brotherton, M. S. [Department of Physics and Astronomy, University of Wyoming, 1000 E. University Avenue, Laramie, WY (United States); Borman, G. A. [Crimean Astrophysical Observatory, P/O Nauchny, Crimea 298409 (Russian Federation); Boroson, T. A. [Las Cumbres Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bottorff, M. C. [Fountainwood Observatory, Department of Physics FJS 149, Southwestern University, 1011 E. University Avenue, Georgetown, TX 78626 (United States); Brown, Jacob E. [Department of Physics and Astronomy, University of Missouri, Columbia (United States); Crawford, S. M. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); and others

    2017-05-10

    We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a “changing look” AGN and a broad-line radio galaxy. Based on continuum-H β lags, we measure black hole masses for all five targets. We also obtain H γ and He ii λ 4686 lags for all objects except 3C 382. The He ii λ 4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100–300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

  3. Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

    International Nuclear Information System (INIS)

    Fausnaugh, M. M.; Denney, K. D.; Peterson, B. M.; Kochanek, C. S.; Pogge, R. W.; Brown, Jonathan S.; Coker, C. T.; Grier, C. J.; Beatty, Thomas G.; Bentz, M. C.; Rosa, G. De; Adams, S. M.; Barth, A. J.; Bhattacharjee, A.; Brotherton, M. S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brown, Jacob E.; Crawford, S. M.

    2017-01-01

    We present the first results from an optical reverberation mapping campaign executed in 2014 targeting the active galactic nuclei (AGNs) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a “changing look” AGN and a broad-line radio galaxy. Based on continuum-H β lags, we measure black hole masses for all five targets. We also obtain H γ and He ii λ 4686 lags for all objects except 3C 382. The He ii λ 4686 lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100–300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

  4. Suitable reverberation time for halls for rock and pop music

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2010-01-01

    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of popular music, including rock and pop. Objective measurements were made of the acoustics of 20 rock music venues in Denmark....... The best-rated halls in the study have reverberation times that are approximately frequency independent from 0.6 to 1.2 s for hall volumes from 1000 to 6000 m3. The worst rated halls in the study had significantly higher reverberation times in the 63 and 125 Hz bands. Since most audiences at rock concerts...... are standing, absorption coefficients were measured with a standing audience from 63 Hz to 4 kHz. These measurements showed that a standing audience absorbs about five times as much energy in mid-/high-frequency bands as in low-frequency bands....

  5. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    Science.gov (United States)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  6. Seabed Scattering from Low Frequency Reverberation Measurements

    Science.gov (United States)

    2015-09-30

    attenuation are consistent with the SAX99 measurement at 25 Hz and 1000 Hz. The results are helpful for the analysis of shear wave effects on long-range...answers to the second question. Carey et al. hypothesized that “The discrepancy can be explained because the inverse analysis inferences were made with the...introduced by an imaginary ideal pressure- release boundary located a distance of P= 4p wavelength below the true seabed boundary, i.e., a “hidden depth” DH

  7. Continuing Long Term Optical and Infrared Reverberation Mapping of 17 Sloan Digital Sky Survey Quasars

    Science.gov (United States)

    Gorjian, Varoujan; Barth, Aaron; Brandt, Niel; Dawson, Kyle; Green, Paul; Ho, Luis; Horne, Keith; Jiang, Linhua; McGreer, Ian; Schneider, Donald; Shen, Yue; Tao, Charling

    2018-05-01

    Previous Spitzer reverberation monitoring projects searching for UV/optical light absorbed and re-emitted in the IR by dust have been limited to low luminosity active galactic nuclei (AGN) that could potentially show reverberation within a single cycle ( 1 year). Cycle 11-12's two year baseline allowed for the reverberation mapping of 17 high-luminosity quasars from the Sloan Digital Sky Survey Reverberation Mapping project. We continued this monitoring in Cycle 13 and now propose to extend this program in Cycle 14. By combining ground-based monitoring from Pan-STARRS, CFHT, and Steward Observatory telescopes with Spitzer data we have for the first time detected dust reverberation in quasars. By continuing observations with this unqiue combination of resources we should detect reverberation in more objects and reduce the uncertainties for the remaining sources.

  8. Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

    Science.gov (United States)

    Kirichok, A. V.; Kuklin, V. M.; Pryimak, A. V.; Zagorodny, A. G.

    2015-09-01

    The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

  9. Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kirichok, A. V., E-mail: sandyrcs@gmail.com; Kuklin, V. M.; Pryimak, A. V. [Institute for High Technologies, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022 (Ukraine); Zagorodny, A. G. [Bogolyubov Institute for Theoretical Physics, 14-b, Metrolohichna str., Kiev 03680 (Ukraine)

    2015-09-15

    The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

  10. Comment on "Localized water reverberation phases and its impact on back-projection images" by Yue et al. [2017

    Science.gov (United States)

    Fan, W.; Shearer, P. M.

    2017-12-01

    Fan and Shearer [2016] analyzed the 2012 Mw 7.2 Sumatra earthquake and reported that the earthquake dynamically triggered early aftershock/aftershocks 150 km away from the mainshock and 50 s later. The early aftershock/aftershocks were detected with teleseismic P-wave back-projection, coincided with passing surface waves, and showed observable seismic waveforms in a wide frequency range (0.02—5 Hz). Recently, however, Yue et al. [2017] interpreted these coda arrivals as water reverberations from the mainshock, based mostly on EGF analysis of a nearby M6 earthquake and a water-phase synthetic test. Here, we show detailed back-projection and waveform analysis of three M6 earthquakes within 100km of the Mw 7.2 earthquake, including the EGF event analyzed in Yue et al. [2017]. In addition, we examine the waveforms of three M5.5 reverse faulting earthquakes close to our detected early aftershock landward of the trench. Our results show that the coda energy in question is more likely caused by a separate earthquake near the trench than by a mainshock water reverberation phase, thus supporting our earlier conclusion that the detected coherent radiators are likely to be dynamically triggered early aftershock/aftershocks.

  11. A novel technique to measure intensity fluctuations in EUV images and to detect coronal sound waves nearby active regions

    Science.gov (United States)

    Stenborg, G.; Marsch, E.; Vourlidas, A.; Howard, R.; Baldwin, K.

    2011-02-01

    Context. In the past years, evidence for the existence of outward-moving (Doppler blue-shifted) plasma and slow-mode magneto-acoustic propagating waves in various magnetic field structures (loops in particular) in the solar corona has been found in ultraviolet images and spectra. Yet their origin and possible connection to and importance for the mass and energy supply to the corona and solar wind is still unclear. There has been increasing interest in this problem thanks to the high-resolution observations available from the extreme ultraviolet (EUV) imagers on the Solar TErrestrial RElationships Observatory (STEREO) and the EUV spectrometer on the Hinode mission. Aims: Flows and waves exist in the corona, and their signatures appear in EUV imaging observations but are extremely difficult to analyse quantitatively because of their weak intensity. Hence, such information is currently available mostly from spectroscopic observations that are restricted in their spatial and temporal coverage. To understand the nature and origin of these fluctuations, imaging observations are essential. Here, we present measurements of the speed of intensity fluctuations observed along apparently open field lines with the Extreme UltraViolet Imagers (EUVI) onboard the STEREO mission. One aim of our paper is to demonstrate that we can make reliable kinematic measurements from these EUV images, thereby complementing and extending the spectroscopic measurements and opening up the full corona for such an analysis. Another aim is to examine the assumptions that lead to flow versus wave interpretation for these fluctuations. Methods: We have developed a novel image-processing method by fusing well established techniques for the kinematic analysis of coronal mass ejections (CME) with standard wavelet analysis. The power of our method lies with its ability to recover weak intensity fluctuations along individual magnetic structures at any orientation , anywhere within the full solar disk , and

  12. EVALUATION OF REVERBERATION TIME IN THE CLASSROOM (CASE OF CLASSROOM AT DEPARTMENT OF ARCHITECTURE, UNIVERSITAS SEBELAS MARET

    Directory of Open Access Journals (Sweden)

    ISWATI Tri Yuni

    2016-12-01

    Full Text Available This study took place in three rooms in one building, give and take the external conditions were relatively similar. The study aims to observe the level of acoustic comfort and suggest strategies to improve the acoustic comfort by modifying materials and dimensions of the materials. The modification is much needed in practice since the user critize the acoustical comfort of the room. The method applied was simply measuring the condition of the rooms using laser distance meter and sound level meter, taking notes on the characteristic of the material used, and developing simulation based on several modifications in materials and dimensions of the materials. The result of the simulation was then being compared to the standart of reverberation time. The conclusion of the study was made into three points: (1 the acoustic condition in the rooms are indeed not meeting the standart to ensure users’ comfort, (2 the reverberation time is better when additional plasterboard ceiling are built, thus changing the rooms’ dimension; and (3 the noise in each room is not significantly reduced even after the additional ceiling built. The simulation in this study was done through the help of Ecotect 2011.

  13. Timbral aspects of reproduced sound in small rooms. I

    DEFF Research Database (Denmark)

    Bech, Søren

    1995-01-01

    , has been simulated using an electroacoustic setup. The model included the direct sound, 17 individual reflections, and the reverberant field. The threshold of detection and just-noticeable differences for an increase in level were measured for individual reflections using eight subjects for noise......This paper reports some of the influences of individual reflections on the timbre of reproduced sound. A single loudspeaker with frequency-independent directivity characteristics, positioned in a listening room of normal size with frequency-independent absorption coefficients of the room surfaces...... and speech. The results have shown that the first-order floor and ceiling reflections are likely to individually contribute to the timbre of reproduced speech. For a noise signal, additional reflections from the left sidewall will contribute individually. The level of the reverberant field has been found...

  14. Multichannel sound reinforcement systems at work in a learning environment

    Science.gov (United States)

    Malek, John; Campbell, Colin

    2003-04-01

    Many people have experienced the entertaining benefits of a surround sound system, either in their own home or in a movie theater, but another application exists for multichannel sound that has for the most part gone unused. This is the application of multichannel sound systems to the learning environment. By incorporating a 7.1 surround processor and a touch panel interface programmable control system, the main lecture hall at the University of Michigan Taubman College of Architecture and Urban Planning has been converted from an ordinary lecture hall to a working audiovisual laboratory. The multichannel sound system is used in a wide variety of experiments, including exposure to sounds to test listeners' aural perception of the tonal characteristics of varying pitch, reverberation, speech transmission index, and sound-pressure level. The touch panel's custom interface allows a variety of user groups to control different parts of the AV system and provides preset capability that allows for numerous system configurations.

  15. Study on The Effectiveness of Egg Tray and Coir Fibre as A Sound Absorber

    Science.gov (United States)

    Kaamin, Masiri; Farah Atiqah Ahmad, Nor; Ngadiman, Norhayati; Kadir, Aslila Abdul; Razali, Siti Nooraiin Mohd; Mokhtar, Mardiha; Sahat, Suhaila

    2018-03-01

    Sound or noise pollution has become one major issues to the community especially those who lived in the urban areas. It does affect the activity of human life. This excessive noise is mainly caused by machines, traffic, motor vehicles and also any unwanted sounds that coming from outside and even from the inside of the building. Such as a loud music. Therefore, the installation of sound absorption panel is one way to reduce the noise pollution inside a building. The selected material must be a porous and hollow in order to absorb high frequency sound. This study was conducted to evaluate the potential of egg tray and coir fibre as a sound absorption panel. The coir fibre has a good coefficient value which make it suitable as a sound absorption material and can replace the traditional material; syntactic and wooden material. The combination of pyramid shape of egg tray can provide a large surface for uniform sound reflection. This study was conducted by using a panel with size 1 m x 1 m with a thickness of 6 mm. This panel consist of egg tray layer, coir fibre layer and a fabric as a wrapping for the aesthetic value. Room reverberation test has been carried to find the loss of reverberation time (RT). Result shows that, a reverberation time reading is on low frequency, which is 125 Hz to 1600 Hz. Within these frequencies, this panel can shorten the reverberation time of 5.63s to 3.60s. Hence, from this study, it can be concluded that the selected materials have the potential as a good sound absorption panel. The comparison is made with the previous research that used egg tray and kapok as a sound absorption panel.

  16. Study on The Effectiveness of Egg Tray and Coir Fibre as A Sound Absorber

    Directory of Open Access Journals (Sweden)

    Kaamin Masiri

    2018-01-01

    Full Text Available Sound or noise pollution has become one major issues to the community especially those who lived in the urban areas. It does affect the activity of human life. This excessive noise is mainly caused by machines, traffic, motor vehicles and also any unwanted sounds that coming from outside and even from the inside of the building. Such as a loud music. Therefore, the installation of sound absorption panel is one way to reduce the noise pollution inside a building. The selected material must be a porous and hollow in order to absorb high frequency sound. This study was conducted to evaluate the potential of egg tray and coir fibre as a sound absorption panel. The coir fibre has a good coefficient value which make it suitable as a sound absorption material and can replace the traditional material; syntactic and wooden material. The combination of pyramid shape of egg tray can provide a large surface for uniform sound reflection. This study was conducted by using a panel with size 1 m x 1 m with a thickness of 6 mm. This panel consist of egg tray layer, coir fibre layer and a fabric as a wrapping for the aesthetic value. Room reverberation test has been carried to find the loss of reverberation time (RT. Result shows that, a reverberation time reading is on low frequency, which is 125 Hz to 1600 Hz. Within these frequencies, this panel can shorten the reverberation time of 5.63s to 3.60s. Hence, from this study, it can be concluded that the selected materials have the potential as a good sound absorption panel. The comparison is made with the previous research that used egg tray and kapok as a sound absorption panel.

  17. Waveform analysis of sound

    CERN Document Server

    Tohyama, Mikio

    2015-01-01

    What is this sound? What does that sound indicate? These are two questions frequently heard in daily conversation. Sound results from the vibrations of elastic media and in daily life provides informative signals of events happening in the surrounding environment. In interpreting auditory sensations, the human ear seems particularly good at extracting the signal signatures from sound waves. Although exploring auditory processing schemes may be beyond our capabilities, source signature analysis is a very attractive area in which signal-processing schemes can be developed using mathematical expressions. This book is inspired by such processing schemes and is oriented to signature analysis of waveforms. Most of the examples in the book are taken from data of sound and vibrations; however, the methods and theories are mostly formulated using mathematical expressions rather than by acoustical interpretation. This book might therefore be attractive and informative for scientists, engineers, researchers, and graduat...

  18. Musical Sound, Instruments, and Equipment

    Science.gov (United States)

    Photinos, Panos

    2017-12-01

    'Musical Sound, Instruments, and Equipment' offers a basic understanding of sound, musical instruments and music equipment, geared towards a general audience and non-science majors. The book begins with an introduction of the fundamental properties of sound waves, and the perception of the characteristics of sound. The relation between intensity and loudness, and the relation between frequency and pitch are discussed. The basics of propagation of sound waves, and the interaction of sound waves with objects and structures of various sizes are introduced. Standing waves, harmonics and resonance are explained in simple terms, using graphics that provide a visual understanding. The development is focused on musical instruments and acoustics. The construction of musical scales and the frequency relations are reviewed and applied in the description of musical instruments. The frequency spectrum of selected instruments is explored using freely available sound analysis software. Sound amplification and sound recording, including analog and digital approaches, are discussed in two separate chapters. The book concludes with a chapter on acoustics, the physical factors that affect the quality of the music experience, and practical ways to improve the acoustics at home or small recording studios. A brief technical section is provided at the end of each chapter, where the interested reader can find the relevant physics and sample calculations. These quantitative sections can be skipped without affecting the comprehension of the basic material. Questions are provided to test the reader's understanding of the material. Answers are given in the appendix.

  19. Foley Sounds vs Real Sounds

    DEFF Research Database (Denmark)

    Trento, Stefano; Götzen, Amalia De

    2011-01-01

    This paper is an initial attempt to study the world of sound effects for motion pictures, also known as Foley sounds. Throughout several audio and audio-video tests we have compared both Foley and real sounds originated by an identical action. The main purpose was to evaluate if sound effects...

  20. In-situ testing of aircraft and satellites using a transportable reverberation chamber

    NARCIS (Netherlands)

    Leferink, Frank Bernardus Johannes

    2009-01-01

    A transportable reverberation chamber with vibrating walls to create high field strength has been developed, called Vibrating Intrinsic Reverberation Chamber (VIRC). It creates a statistically uniform electromagnetic field without the use of a rotating mode stirrer, resulting in a better homogeneity

  1. Study of reverberation pattern and its cancellation method in shallow water

    Directory of Open Access Journals (Sweden)

    Yang Shiuh-Kuang

    2007-01-01

    Full Text Available In shallow water, the primary limitation of the performance of active sonar is the reverberation that originates from volume and boundaries scattering as well as multi-path propagation. There­fore, reverberation cancelation is an important research topic for increasing the performance of active sonar in shallow water. In this research, the reverberation pattern is simulated using MAT­LAB software. The simulated frequency is 30-kHz in the research. There are two main aims of this work. The first is to create the signals that include the reverberation and the target. The second is to perform the reverberation cancelation for the active sonar in shallow water. The analysis of the reverberation for the spherical target is based on the propagation theory of image source, surface scattering of Rayleigh criterion of roughness, bottom scattering of Lambert’s Law, and multiple scattering. The signal containing the reverberation and the target is then compressed or enhanced by AGC (Automatic Gain Control. The echo of the target is then distinguished through the method of cross correlation. The follow­ing phenomena can be found: (a AGC can compress the signal in a specific dynamic range. (b cross correlation can be used to locate and distinguish the echoes of the target in a high reverberation environment.

  2. Reverberation chambers a la carte: an overview of the different mode-stirring techniques

    NARCIS (Netherlands)

    Serra, R.; Marvin, A.C.; Moglie, F.; Mariani Primiani, V.; Cozza, A.; Arnaut, L.R.; Huang, Y.; Hatfield, M.O.; Klingler, M.; Leferink, F.

    2017-01-01

    Reverberation chambers (RC), a name inspired in room acoustics, are also known in literature as reverberating, reverb, mode-stirred or mode-tuned chambers. In their basic form, they consist of a shielded metallic enclosure, forming a cavity resonator, together with some mode-stirring mechanism. The

  3. Reverberation Chambers à La Carte : An Overview of the Different Mode-Stirring Techniques

    NARCIS (Netherlands)

    Serra, Ramiro; Marvin, Andy C.; Moglie, Franco; Mariani Primiani, Valter; Cozza, Andrea; Arnaut, Luk R.; Huang, Yi; Hatfield, Michael O.; Klingler, Marco; Leferink, Frank

    2017-01-01

    Reverberation chambers (RC), a name inspired in room acoustics, are also known in literature as reverberating, reverb, mode-stirred or mode-tuned chambers. In their basic form, they consist of a shielded metallic enclosure, forming a cavity resonator, together with some mode-stirring mechanism. The

  4. Differences in directional sound source behavior and perception between assorted computer room models

    DEFF Research Database (Denmark)

    Vigeant, Michelle C.; Wang, Lily M.; Rindel, Jens Holger

    2004-01-01

    considering reverberation time. However, for the three other parameters evaluated (sound pressure level, clarity index and lateral fraction), the changing diffusivity of the room does not diminish the importance of the directivity. The study therefore shows the importance of considering source directivity......Source directivity is an important input variable when using room acoustic computer modeling programs to generate auralizations. Previous research has shown that using a multichannel anechoic recording can produce a more natural sounding auralization, particularly as the number of channels...

  5. A transparency model and its applications for simulation of reflector arrays and sound transmission (A)

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2006-01-01

    The paper describes a new method for simulating the frequency-dependent reflection and transmission of reflector arrays, and the frequency-dependent airborne sound insulation between rooms by means of a room acoustic computer model. The method makes use of a transparency method in the ray...... of the partition, and this is useful for the auralization of sound transmission through different building constructions. The acoustic properties like volume, reverberation time, and the area of the transmitting surfaces are included in the simulation....

  6. Sound absorption study on acoustic panel from kapok fiber and egg tray

    Science.gov (United States)

    Kaamin, Masiri; Mahir, Nurul Syazwani Mohd; Kadir, Aslila Abd; Hamid, Nor Baizura; Mokhtar, Mardiha; Ngadiman, Norhayati

    2017-12-01

    Noise also known as a sound, especially one that is loud or unpleasant or that causes disruption. The level of noise can be reduced by using sound absorption panel. Currently, the market produces sound absorption panel, which use synthetic fibers that can cause harmful effects to the health of consumers. An awareness of using natural fibers from natural materials gets attention of some parties to use it as a sound absorbing material. Therefore, this study was conducted to investigate the potential of sound absorption panel using egg trays and kapok fibers. The test involved in this study was impedance tube test which aims to get sound absorption coefficient (SAC). The results showed that there was good sound absorption at low frequency from 0 Hz up to 900 Hz where the maximum absorption coefficient was 0.950 while the maximum absorption at high frequencies was 0.799. Through the noise reduction coefficient (NRC), the material produced NRC of 0.57 indicates that the materials are very absorbing. In addition, the reverberation room test was carried out to get the value of reverberation time (RT) in unit seconds. Overall this panel showed good results at low frequencies between 0 Hz up to 1500 Hz. In that range of frequency, the maximum reverberation time for the panel was 3.784 seconds compared to the maximum reverberation time for an empty room was 5.798 seconds. This study indicated that kapok fiber and egg tray as the material of absorption panel has a potential as environmental and cheap products in absorbing sound at low frequency.

  7. Statistics of the electromagnetic response of a chaotic reverberation chamber

    Directory of Open Access Journals (Sweden)

    J.-B. Gros

    2015-11-01

    Full Text Available This article presents a study of the electromagnetic re- sponse of a chaotic reverberation chamber (RC in the pres- ence of losses. By means of simulations and of experi- ments, the fluctuations in the maxima of the field obtained in a conventional mode-stirred RC are compared with those in a chaotic RC in the neighborhood of the Lowest Useable Frequency (LUF. The present work illustrates that the uni- versal spectral and spatial statistical properties of chaotic RCs allow to meet more adequately the criteria required by the Standard IEC 61000-4-21 to perform tests of electro- magnetic compatibility.

  8. DOA Estimation of Audio Sources in Reverberant Environments

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Nielsen, Jesper Kjær; Heusdens, Richard

    2016-01-01

    Reverberation is well-known to have a detrimental impact on many localization methods for audio sources. We address this problem by imposing a model for the early reflections as well as a model for the audio source itself. Using these models, we propose two iterative localization methods...... that estimate the direction-of-arrival (DOA) of both the direct path of the audio source and the early reflections. In these methods, the contribution of the early reflections is essentially subtracted from the signal observations before localization of the direct path component, which may reduce the estimation...

  9. Computer model of a reverberant and parallel circuit coupling

    Science.gov (United States)

    Kalil, Camila de Andrade; de Castro, Maria Clícia Stelling; Cortez, Célia Martins

    2017-11-01

    The objective of the present study was to deepen the knowledge about the functioning of the neural circuits by implementing a signal transmission model using the Graph Theory in a small network of neurons composed of an interconnected reverberant and parallel circuit, in order to investigate the processing of the signals in each of them and the effects on the output of the network. For this, a program was developed in C language and simulations were done using neurophysiological data obtained in the literature.

  10. Room acoustic enhancement in a small hall with very low natural reverberation time

    DEFF Research Database (Denmark)

    Gade, Anders Christian

    1996-01-01

    natural combinations of room acoustic properties. Consequently, the natural reverberation time in a newly opened 350 seat multipurpose hall in Denmark was designed as low as 0.7 sec. Two different reverberation enhancement systems were considered and tested in the hall. The objective and subjective...... testing results are reported and compared with previous results obtained in another small hall supplied with a similar enhancement system. The results concerning 'realism' are also compared with acoustic properties found in 'natural' halls of different sizes and reverberation times.......In small multipurpose halls to be equipped with electronic reverberation enhancement systems, selecting a very low natural reverberation time is advantageous for several reasons. It will 1) reduce the risk of feedback, 2) increase the possible range of room acoustic variation and 3) allow for more...

  11. Imaging the Moho beneath Sedimentary Basins: A Comparative Study of Virtual Deep Seismic Sounding (VDSS) and P Wave Receiver Functions (PRF)

    Science.gov (United States)

    Liu, T.; Klemperer, S. L.; Yu, C.; Ning, J.

    2017-12-01

    In the past decades, P wave receiver functions (PRF) have been routinely used to image the Moho, although it is well known that PRFs are susceptible to contamination from sedimentary multiples. Recently, Virtual Deep Seismic Sounding (VDSS) emerged as a novel method to image the Moho. However, despite successful applications of VDSS on multiple datasets from different areas, how sedimentary basins affect the waveforms of post-critical SsPmp, the Moho reflection phase used in VDSS, is not widely understood. Here, motivated by a dataset collected in the Ordos plateau, which shows distinct effects of sedimentary basins on SsPmp and Pms waveforms, we use synthetic seismograms to study the effects of sedimentary basins on SsPmp and Pms, the phases used in VDSS and PRF respectively. The results show that when the sedimentary thickness is on the same order of magnitude as the dominant wavelength of the incident S wave, SsPmp amplitude decreases significantly with S velocity of the sedimentary layer, whereas increasing sedimentary thickness has little effect in SsPmp amplitude. Our explanation is that the low S velocity layer at the virtual source reduces the incident angle of S wave at the free surface, thus decreases the S-to-P reflection coefficient at the virtual source. In addition, transmission loss associated with the bottom of sedimentary basins also contributes to reducing SsPmp amplitude. This explains not only our observations from the Ordos plateau, but also observations from other areas where post-critical SsPmp is expected to be observable, but instead is too weak to be identified. As for Pms, we observe that increasing sedimentary thickness and decreasing sedimentary velocities both can cause interference between sedimentary multiples and Pms, rendering the Moho depths inferred from Pms arrival times unreliable. The reason is that although Pms amplitude does not vary with sedimentary thickness or velocities, as sedimentary velocities decrease and thickness

  12. Acoustical monitoring of diesel engines in reverberant environment

    International Nuclear Information System (INIS)

    Mein, M.

    1995-10-01

    The feed-back knowledge of emergency diesel generators in nuclear power plants shows that some malfunctions, mainly affecting fuel-injection or distribution system of the engine can be heard and detected by experienced maintenance agents. This study consists in the feasibility,v of acoustical monitoring of those diesel engines, taking into account the reverberant environment of the machine. The operating cycle of the diesel is composed of transient events (injection, combustion, valve closure...) which generate highly non stationary acoustical signals. The detection of a malfunction appearing on such transients requires the use of adapted signal processing techniques. Visual analysis of the phenomena is first proceeded using time-frequency and time-scale representations. The second step will be parametric modeling of acoustical signatures for the extraction of characteristic parameters, in order to characterize the fault and to use an automatic classification system. The lest part of the study will concern the evaluation of the robustness of the detection methods in regard to acoustical reverberation. (author). 10 refs., 6 figs

  13. Imagining Sound

    DEFF Research Database (Denmark)

    Grimshaw, Mark; Garner, Tom Alexander

    2014-01-01

    We make the case in this essay that sound that is imagined is both a perception and as much a sound as that perceived through external stimulation. To argue this, we look at the evidence from auditory science, neuroscience, and philosophy, briefly present some new conceptual thinking on sound...... that accounts for this view, and then use this to look at what the future might hold in the context of imagining sound and developing technology....

  14. Development of sound absorption measuring system with acoustic chamber; Kogata kyuon koka sokutei sochi no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Takahira, M.; Noba, M. [Toyota Motor Corp., Aichi (Japan); Matsuoka, H. [Nippon Soken, Inc., Tokyo (Japan)

    1998-05-01

    In order to measure sound absorption performance necessary to develop sound absorption materials, development was made on a device consisting of a small sound box capable of measurement inexpensively and easily, as a measure against the reverberation chamber method. In order to obtain stabilized diffusion sound internally, the sound box has a shape of asymmetric seven-side body in which sides do not face squarely with each other. The box was so sized that a large number of resonant vibration postures can be constituted at the targeted frequency simultaneously in the box. The box has a commercially available cone speaker with good acoustic output characteristics in frequency range of higher than 500 Hz installed on an inner side of the box. The sound source uses a method to derive sound absorption rate from difference of sound pressure levels. In order to eliminate need of averaging treatment by using a multi-point measurement inside the box, a discussion was given to provide an opening on part of the box to place the sound receiving point outside the opening. A square test piece is placed on the floor 0.5 meter or more away from the speaker in the box. As a result of the experiment, it was verified that the sound absorption rate obtained by this device corresponds well with that by the reverberation chamber method. The size of the test piece was also found adequate. 2 refs., 11 figs., 1 tab.

  15. The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

    Science.gov (United States)

    Hozman, Aron D.; Hughes, William O.; McNelis, Mark E.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA's space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 cu ft in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada's acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  16. Acoustical monitoring of diesel engines in reverberant environment; Methodes de surveillance acoustique des diesels en milieu reverberant

    Energy Technology Data Exchange (ETDEWEB)

    Mein, M.

    1995-10-01

    The feed-back knowledge of emergency diesel generators in nuclear power plants shows that some malfunctions, mainly affecting fuel-injection or distribution system of the engine can be heard and detected by experienced maintenance agents. This study consists in the feasibility,v of acoustical monitoring of those diesel engines, taking into account the reverberant environment of the machine. The operating cycle of the diesel is composed of transient events (injection, combustion, valve closure...) which generate highly non stationary acoustical signals. The detection of a malfunction appearing on such transients requires the use of adapted signal processing techniques. Visual analysis of the phenomena is first proceeded using time-frequency and time-scale representations. The second step will be parametric modeling of acoustical signatures for the extraction of characteristic parameters, in order to characterize the fault and to use an automatic classification system. The lest part of the study will concern the evaluation of the robustness of the detection methods in regard to acoustical reverberation. (author). 10 refs., 6 figs.

  17. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.

  18. Sounds of Space

    Science.gov (United States)

    Gurnett, D. A.

    2005-12-01

    Starting in the early 1960s, spacecraft-borne plasma wave instruments revealed that space is filled with an astonishing variety of radio and plasma wave sounds, which have come to be called "sounds of space." For over forty years these sounds have been collected and played to a wide variety of audiences, often as the result of press conferences or press releases involving various NASA projects for which the University of Iowa has provided plasma wave instruments. This activity has led to many interviews on local and national radio programs, and occasionally on programs haviang world-wide coverage, such as the BBC. As a result of this media coverage, we have been approached many times by composers requesting copies of our space sounds for use in their various projects, many of which involve electronic synthesis of music. One of these collaborations led to "Sun Rings," which is a musical event produced by the Kronos Quartet that has played to large audiences all over the world. With the availability of modern computer graphic techniques we have recently been attempting to integrate some of these sound of space into an educational audio/video web site that illustrates the scientific principles involved in the origin of space plasma waves. Typically I try to emphasize that a substantial gas pressure exists everywhere in space in the form of an ionized gas called a plasma, and that this plasma can lead to a wide variety of wave phenomenon. Examples of some of this audio/video material will be presented.

  19. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  20. Effects of Varying Reverberation on Music Perception for Young Normal-Hearing and Old Hearing-Impaired Listeners.

    Science.gov (United States)

    Reinhart, Paul N; Souza, Pamela E

    2018-01-01

    Reverberation enhances music perception and is one of the most important acoustic factors in auditorium design. However, previous research on reverberant music perception has focused on young normal-hearing (YNH) listeners. Old hearing-impaired (OHI) listeners have degraded spatial auditory processing; therefore, they may perceive reverberant music differently. Two experiments were conducted examining the effects of varying reverberation on music perception for YNH and OHI listeners. Experiment 1 examined whether YNH listeners and OHI listeners prefer different amounts of reverberation for classical music listening. Symphonic excerpts were processed at a range of reverberation times using a point-source simulation. Listeners performed a paired-comparisons task in which they heard two excerpts with different reverberation times, and they indicated which they preferred. The YNH group preferred a reverberation time of 2.5 s; however, the OHI group did not demonstrate any significant preference. Experiment 2 examined whether OHI listeners are less sensitive to (e, less able to discriminate) differences in reverberation time than YNH listeners. YNH and OHI participants listened to pairs of music excerpts and indicated whether they perceived the same or different amount of reverberation. Results indicated that the ability of both groups to detect differences in reverberation time improved with increasing reverberation time difference. However, discrimination was poorer for the OHI group than for the YNH group. This suggests that OHI listeners are less sensitive to differences in reverberation when listening to music than YNH listeners, which might explain the lack of group reverberation time preferences of the OHI group.

  1. Computational advantages of reverberating loops for sensorimotor learning.

    Science.gov (United States)

    Fortney, Kristen; Tweed, Douglas B

    2012-03-01

    When we learn something new, our brain may store the information in synapses or in reverberating loops of electrical activity, but current theories of motor learning focus almost entirely on the synapses. Here we show that loops could also play a role and would bring advantages: loop-based algorithms can learn complex control tasks faster, with exponentially fewer neurons, and avoid the problem of weight transport. They do all this at a cost: in the presence of long feedback delays, loop algorithms cannot control very fast movements, but in this case, loop and synaptic mechanisms can complement each other-mixed systems quickly learn to make accurate but not very fast motions and then gradually speed up. Loop algorithms explain aspects of consolidation, the role of attention, and the relapses that are sometimes seen after a task has apparently been learned, and they make further predictions.

  2. Source Coding for Wireless Distributed Microphones in Reverberant Environments

    DEFF Research Database (Denmark)

    Zahedi, Adel

    2016-01-01

    . However, it comes with the price of several challenges, including the limited power and bandwidth resources for wireless transmission of audio recordings. In such a setup, we study the problem of source coding for the compression of the audio recordings before the transmission in order to reduce the power...... consumption and/or transmission bandwidth by reduction in the transmission rates. Source coding for wireless microphones in reverberant environments has several special characteristics which make it more challenging in comparison with regular audio coding. The signals which are acquired by the microphones......Modern multimedia systems are more and more shifting toward distributed and networked structures. This includes audio systems, where networks of wireless distributed microphones are replacing the traditional microphone arrays. This allows for flexibility of placement and high spatial diversity...

  3. Prediction of Classroom Reverberation Time using Neural Network

    Science.gov (United States)

    Liyana Zainudin, Fathin; Kadir Mahamad, Abd; Saon, Sharifah; Nizam Yahya, Musli

    2018-04-01

    In this paper, an alternative method for predicting the reverberation time (RT) using neural network (NN) for classroom was designed and explored. Classroom models were created using Google SketchUp software. The NN applied training dataset from the classroom models with RT values that were computed from ODEON 12.10 software. The NN was conducted separately for 500Hz, 1000Hz, and 2000Hz as absorption coefficient that is one of the prominent input variable is frequency dependent. Mean squared error (MSE) and regression (R) values were obtained to examine the NN efficiency. Overall, the NN shows a good result with MSE 0.9. The NN also managed to achieve a percentage of accuracy of 92.53% for 500Hz, 93.66% for 1000Hz, and 93.18% for 2000Hz and thus displays a good and efficient performance. Nevertheless, the optimum RT value is range between 0.75 – 0.9 seconds.

  4. Reverberation mapping of the Seyfert 1 galaxy NGC 7469

    International Nuclear Information System (INIS)

    Peterson, B. M.; Grier, C. J.; Pogge, R. W.; De Rosa, G.; Denney, K. D.; Martini, Paul; Zu, Y.; Kochanek, C. S.; Shappee, B.; Araya Salvo, C.; Beatty, T. G.; Bird, J. C.; Horne, Keith; Bentz, M. C.; Sergeev, S. G.; Borman, G. A.; Kaspi, S.; Minezaki, T.; Siverd, R. J.; Bord, D. J.

    2014-01-01

    A large reverberation-mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hβ λ4861 and He II λ4686 and a central black hole mass measurement M BH ≈ 1 × 10 7 M ☉ , consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hβ measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hβ-emitting broad-line region and the luminosity of the active galactic nucleus. It was necessary to detrend the continuum and Hβ and He II λ4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results.

  5. Reverberation mapping of the Seyfert 1 galaxy NGC 7469

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, B. M.; Grier, C. J.; Pogge, R. W.; De Rosa, G.; Denney, K. D.; Martini, Paul; Zu, Y.; Kochanek, C. S.; Shappee, B.; Araya Salvo, C.; Beatty, T. G.; Bird, J. C. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Horne, Keith [SUPA Physics and Astronomy, University of St. Andrews, Fife KY16 9SS (United Kingdom); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, 25 Park Place, Suite 605, Atlanta, GA 30303 (United States); Sergeev, S. G.; Borman, G. A. [Crimean Astrophysical Observatory, P/O Nauchny Crimea 298409 (Russian Federation); Kaspi, S. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Minezaki, T. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, 181-0015 Tokyo (Japan); Siverd, R. J. [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN 37235 (United States); Bord, D. J., E-mail: peterson.12@osu.edu [Department of Natural Sciences, The University of Michigan—Dearborn, 4901 Evergreen Road, Dearborn, MI 48128 (United States); and others

    2014-11-10

    A large reverberation-mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hβ λ4861 and He II λ4686 and a central black hole mass measurement M {sub BH} ≈ 1 × 10{sup 7} M {sub ☉}, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hβ measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hβ-emitting broad-line region and the luminosity of the active galactic nucleus. It was necessary to detrend the continuum and Hβ and He II λ4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results.

  6. Analysis of room transfer function and reverberant signal statistics

    DEFF Research Database (Denmark)

    Georganti, Eleftheria; Mourjopoulos, John; Jacobsen, Finn

    2008-01-01

    For some time now, statistical analysis has been a valuable tool in analyzing room transfer functions (RTFs). This work examines existing statistical time-frequency models and techniques for RTF analysis (e.g., Schroeder's stochastic model and the standard deviation over frequency bands for the RTF...... magnitude and phase). RTF fractional octave smoothing, as with 1-slash 3 octave analysis, may lead to RTF simplifications that can be useful for several audio applications, like room compensation, room modeling, auralisation purposes. The aim of this work is to identify the relationship of optimal response...... and the corresponding ratio of the direct and reverberant signal. In addition, this work examines the statistical quantities for speech and audio signals prior to their reproduction within rooms and when recorded in rooms. Histograms and other statistical distributions are used to compare RTF minima of typical...

  7. Reverberant acoustic energy in auditoria that comprise systems of coupled rooms

    Science.gov (United States)

    Summers, Jason E.

    2003-11-01

    A frequency-dependent model for reverberant energy in coupled rooms is developed and compared with measurements for a 1:10 scale model and for Bass Hall, Ft. Worth, TX. At high frequencies, prior statistical-acoustics models are improved by geometrical-acoustics corrections for decay within sub-rooms and for energy transfer between sub-rooms. Comparisons of computational geometrical acoustics predictions based on beam-axis tracing with scale model measurements indicate errors resulting from tail-correction assuming constant quadratic growth of reflection density. Using ray tracing in the late part corrects this error. For mid-frequencies, the models are modified to account for wave effects at coupling apertures by including power transmission coefficients. Similarly, statical-acoustics models are improved through more accurate estimates of power transmission measurements. Scale model measurements are in accord with the predicted behavior. The edge-diffraction model is adapted to study transmission through apertures. Multiple-order scattering is theoretically and experimentally shown inaccurate due to neglect of slope diffraction. At low frequencies, perturbation models qualitatively explain scale model measurements. Measurements confirm relation of coupling strength to unperturbed pressure distribution on coupling surfaces. Measurements in Bass Hall exhibit effects of the coupled stage house. High frequency predictions of statistical acoustics and geometrical acoustics models and predictions of coupling apertures all agree with measurements.

  8. Reverberation time influences musical enjoyment with cochlear implants.

    Science.gov (United States)

    Certo, Michael V; Kohlberg, Gavriel D; Chari, Divya A; Mancuso, Dean M; Lalwani, Anil K

    2015-02-01

    To identify factors that enhance the enjoyment of music in cochlear implant (CI) recipients. Specifically, we assessed the hypothesis that variations in reverberation time (RT60) may be linked to variations in the level of musical enjoyment in CI users. Prospective analysis of music enjoyment in normal-hearing individuals. Single tertiary academic medical center. Normal-hearing adults (N = 20) were asked to rate a novel 20-second melody on three enjoyment modalities: musicality, pleasantness, and naturalness. Subjective rating of music excerpts. Participants listened to seven different instruments play the melody, each with five levels (0.2, 1.6, 3.0, 5.0, 10.0 s) of RT60, both with and without CI simulation processing. Linear regression analysis with analysis of variance was used to assess the impact of RT60 on music enjoyment. Without CI simulation, music samples with RT60 = 3.0 seconds were ranked most pleasant and most musical, whereas those with RT60 = 1.6 seconds and RT60 = 3.0 seconds were ranked equally most natural (all p < 0.05). With CI simulation, music samples with RT60 = 0.2 seconds were ranked most pleasant, most musical, and most natural (all p < 0.05). Samples without CI simulation show a preference for middle-range RT60, whereas samples with CI simulation show a negative linear relationship between RT60 and musical enjoyment, with preference for minimal reverberation. Minimization of RT60 may be a useful strategy for increasing musical enjoyment under CI conditions, both in altering existing music as well as in composition of new music.

  9. Are communication activities shaped by environmental constraints in reverberating and absorbing forest habitats?

    Directory of Open Access Journals (Sweden)

    Nicolas Manthevon

    2004-06-01

    Full Text Available In the dense vegetation of temperate or tropical forests, communication processes are constrained by propagation-induced modifications of the transmitted sounds. The presence of leaves, trunks and branches induces important sound reverberation and absorption leading to diminution of the signal energy as well as qualitative modifications. The aim of this paper is to briefly review the different strategies used by birds to manage with these constraints. At the emitter's level, an adapted emission behavior which takes into account both the physical heterogeneities of the forest environment and the temporal variations of the acoustic constraints, is especially useful to control the active space of signaling. The coding of information into acoustic parameters that have different susceptibility to propagation constraints is also of great interest. At the receiver's level, an adaptive reception behavior (listening post and a great tolerance to sound degradation during the decoding process are the keys to an optimal communication process.Na vegetação densa das florestas temperadas ou tropicais, os processos de comunicação são limitados pelas modificações dos sons durante sua propagação. A presença de folhas, troncos e galhos produz uma importante reverberação e absorção do som, provocando uma diminuição da energia do sinal, assim como modificações qualitativas. O objetivo deste artigo é de revisar brevemente as diferentes estratégias usadas por aves para gerenciar essas limitações. Para o emissor, um comportamento de emissão adaptado tanto às heterogeneidades físicas do meio florestal, quanto às variações temporais das exigências acústicas, é particularmente útil para controlar o canal ativo de sinalização. A codificação da informação em parâmetros acústicos com diferentes sensibilidades às exigências de propagação é também de grande valia. Para o receptor, um comportamento adaptado (posto de escuta e uma

  10. Handbook for sound engineers

    CERN Document Server

    Ballou, Glen

    2013-01-01

    Handbook for Sound Engineers is the most comprehensive reference available for audio engineers. All audio topics are explored: if you work on anything related to audio you should not be without this book! The 4th edition of this trusted reference has been updated to reflect changes in the industry since the publication of the 3rd edition in 2002 -- including new technologies like software-based recording systems such as Pro Tools and Sound Forge; digital recording using MP3, wave files and others; mobile audio devices such as iPods and MP3 players. Over 40 topic

  11. On the role of sound in the strong Langmuir turbulence

    International Nuclear Information System (INIS)

    Malkin, V.M.

    1989-01-01

    The main directions in the precision of the theory of strong Langmuir turbulence caused by the necessity of account of sound waves in plasma are preseted. In particular the effect of conversion of short-wave modulations in Langmuir waves induced by sound waves, are briefly described. 8 refs

  12. Unsound Sound

    DEFF Research Database (Denmark)

    Knakkergaard, Martin

    2016-01-01

    This article discusses the change in premise that digitally produced sound brings about and how digital technologies more generally have changed our relationship to the musical artifact, not simply in degree but in kind. It demonstrates how our acoustical conceptions are thoroughly challenged...... by the digital production of sound and, by questioning the ontological basis for digital sound, turns our understanding of the core term substance upside down....

  13. Sound classification of dwellings in the Nordic countries

    DEFF Research Database (Denmark)

    Rindel, Jens Holger; Turunen-Rise, Iiris

    1997-01-01

    be met. The classification system is based on limit values for airborne sound insulation, impact sound pressure level, reverberation time and indoor and outdoor noise levels. The purpose of the standard is to offer a tool for specification of a standardised acoustic climate and to promote constructors......A draft standard INSTA 122:1997 on sound classification of dwellings is for voting as a common national standard in the Nordic countries (Denmark, Norway, Sweden, Finland, Iceland) and in Estonia. The draft standard specifies a sound classification system with four classes A, B, C and D, where...... class C is proposed as the future minimum requirements for new dwellings. The classes B and A define criteria for dwellings with improved or very good acoustic conditions, whereas class D may be used for older, renovated dwellings in which the acoustic quality level of a new dwelling cannot reasonably...

  14. Sound Classification in Hearing Aids Inspired by Auditory Scene Analysis

    Science.gov (United States)

    Büchler, Michael; Allegro, Silvia; Launer, Stefan; Dillier, Norbert

    2005-12-01

    A sound classification system for the automatic recognition of the acoustic environment in a hearing aid is discussed. The system distinguishes the four sound classes "clean speech," "speech in noise," "noise," and "music." A number of features that are inspired by auditory scene analysis are extracted from the sound signal. These features describe amplitude modulations, spectral profile, harmonicity, amplitude onsets, and rhythm. They are evaluated together with different pattern classifiers. Simple classifiers, such as rule-based and minimum-distance classifiers, are compared with more complex approaches, such as Bayes classifier, neural network, and hidden Markov model. Sounds from a large database are employed for both training and testing of the system. The achieved recognition rates are very high except for the class "speech in noise." Problems arise in the classification of compressed pop music, strongly reverberated speech, and tonal or fluctuating noises.

  15. Effects of interaural level differences on the externalization of sound

    DEFF Research Database (Denmark)

    Catic, Jasmina; Santurette, Sébastien; Dau, Torsten

    2012-01-01

    Distant sound sources in our environment are perceived as externalized and are thus properly localized in both direction and distance. This is due to the acoustic filtering by the head, torso, and external ears, which provides frequency-dependent shaping of binaural cues such as interaural level...... differences (ILDs) and interaural time differences (ITDs). In rooms, the sound reaching the two ears is further modified by reverberant energy, which leads to increased fluctuations in short-term ILDs and ITDs. In the present study, the effect of ILD fluctuations on the externalization of sound......, for sounds that contain frequencies above about 1 kHz the ILD fluctuations were found to be an essential cue for externalization....

  16. High second-language proficiency protects against the effects of reverberation on listening comprehension.

    Science.gov (United States)

    Sörqvist, Patrik; Hurtig, Anders; Ljung, Robert; Rönnberg, Jerker

    2014-04-01

    The purpose of this experiment was to investigate whether classroom reverberation influences second-language (L2) listening comprehension. Moreover, we investigated whether individual differences in baseline L2 proficiency and in working memory capacity (WMC) modulate the effect of reverberation time on L2 listening comprehension. The results showed that L2 listening comprehension decreased as reverberation time increased. Participants with higher baseline L2 proficiency were less susceptible to this effect. WMC was also related to the effect of reverberation (although just barely significant), but the effect of WMC was eliminated when baseline L2 proficiency was statistically controlled. Taken together, the results suggest that top-down cognitive capabilities support listening in adverse conditions. Potential implications for the Swedish national tests in English are discussed. © 2014 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  17. Sound Velocity in Soap Foams

    International Nuclear Information System (INIS)

    Wu Gong-Tao; Lü Yong-Jun; Liu Peng-Fei; Li Yi-Ning; Shi Qing-Fan

    2012-01-01

    The velocity of sound in soap foams at high gas volume fractions is experimentally studied by using the time difference method. It is found that the sound velocities increase with increasing bubble diameter, and asymptotically approach to the value in air when the diameter is larger than 12.5 mm. We propose a simple theoretical model for the sound propagation in a disordered foam. In this model, the attenuation of a sound wave due to the scattering of the bubble wall is equivalently described as the effect of an additional length. This simplicity reasonably reproduces the sound velocity in foams and the predicted results are in good agreement with the experiments. Further measurements indicate that the increase of frequency markedly slows down the sound velocity, whereas the latter does not display a strong dependence on the solution concentration

  18. Reponse Dynamique D'un Panneau Soumis a un Environnement Acoustique Reverberant

    Science.gov (United States)

    Nelisse, Hugues

    1995-01-01

    The present thesis deals with the problem of the dynamic response of a homeogenous flexible panel immersed in a reverberant field. This problem takes place in the framework of aerospace problems in which satellites substructures are submitted to high acoustic levels during the launchers lift-off. The thesis is divided in four main parts. The first one presents an integral formulation that allows to treat the case of a flexible panel placed in a rectangular room. A semi-analytical resolution is used to identify the two main physical unknowns of the problem, the acoustic pressure jump across the panel and the panel deflection. The second part is dedicated to the study of the notion of diffuse field. Through a bibliographic review, two indicators are used to characterize the sound field in the room and in the free field. Precise criterions related to the modal density of the room are discussed. Analysis and discussion on the conditions which allow the establishment of a diffuse field are also presented. In the third part, a theoretical formulation which allows to treat the problem of an unbaffled panel submitted to an acoustic excitation in the free field is presented. The singularity problem due to the use of the free-space Green's function is overcame by the use of a variational principle. A semi-analytical approach is used to solve the linear system of equations. Emphasis is put on the fact that the excitation is acoustic. The theory is validated with the help of an existing boundary element numerical code. The last part is first dedicated to a comparative study of the two developed approaches and to a phenomenological study. Studies of the effect of the structural damping on the panel vibrations are presented as well as analysis of some different approximations generally used in this type of problem.

  19. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2008-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  20. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2010-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  1. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2007-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  2. Performance of active feedforward control systems in non-ideal, synthesized diffuse sound fields.

    Science.gov (United States)

    Misol, Malte; Bloch, Christian; Monner, Hans Peter; Sinapius, Michael

    2014-04-01

    The acoustic performance of passive or active panel structures is usually tested in sound transmission loss facilities. A reverberant sending room, equipped with one or a number of independent sound sources, is used to generate a diffuse sound field excitation which acts as a disturbance source on the structure under investigation. The spatial correlation and coherence of such a synthesized non-ideal diffuse-sound-field excitation, however, might deviate significantly from the ideal case. This has consequences for the operation of an active feedforward control system which heavily relies on the acquisition of coherent disturbance source information. This work, therefore, evaluates the spatial correlation and coherence of ideal and non-ideal diffuse sound fields and considers the implications on the performance of a feedforward control system. The system under consideration is an aircraft-typical double panel system, equipped with an active sidewall panel (lining), which is realized in a transmission loss facility. Experimental results for different numbers of sound sources in the reverberation room are compared to simulation results of a comparable generic double panel system excited by an ideal diffuse sound field. It is shown that the number of statistically independent noise sources acting on the primary structure of the double panel system depends not only on the type of diffuse sound field but also on the sample lengths of the processed signals. The experimental results show that the number of reference sensors required for a defined control performance exhibits an inverse relationship to control filter length.

  3. Experimental investigation of sound absorption of acoustic wedges for anechoic chambers

    Science.gov (United States)

    Belyaev, I. V.; Golubev, A. Yu.; Zverev, A. Ya.; Makashov, S. Yu.; Palchikovskiy, V. V.; Sobolev, A. F.; Chernykh, V. V.

    2015-09-01

    The results of measuring the sound absorption by acoustic wedges, which were performed in AC-3 and AC-11 reverberation chambers at the Central Aerohydrodynamic Institute (TsAGI), are presented. Wedges of different densities manufactured from superfine basaltic and thin mineral fibers were investigated. The results of tests of these wedges were compared to the sound absorption of wedges of the operating AC-2 anechoic facility at TsAGI. It is shown that basaltic-fiber wedges have better sound-absorption characteristics than the investigated analogs and can be recommended for facing anechoic facilities under construction.

  4. Estimating the diffuseness of sound fields: A wavenumber analysis method

    DEFF Research Database (Denmark)

    Nolan, Melanie; Davy, John L.; Brunskog, Jonas

    2017-01-01

    The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The diffuse sound field is generally described as composed of plane waves with random phases, which wave number vectors are uniformly distributed over all angles of incidence. In this study, an interpretat...

  5. Sound Zones

    DEFF Research Database (Denmark)

    Møller, Martin Bo; Olsen, Martin

    2017-01-01

    Sound zones, i.e. spatially confined regions of individual audio content, can be created by appropriate filtering of the desired audio signals reproduced by an array of loudspeakers. The challenge of designing filters for sound zones is twofold: First, the filtered responses should generate...... an acoustic separation between the control regions. Secondly, the pre- and post-ringing as well as spectral deterioration introduced by the filters should be minimized. The tradeoff between acoustic separation and filter ringing is the focus of this paper. A weighted L2-norm penalty is introduced in the sound...

  6. REVERBERATION MAPPING RESULTS FOR FIVE SEYFERT 1 GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Peterson, B. M.; Pogge, R. W.; Martini, Paul; Zu, Y.; Kochanek, C. S.; Shappee, B.; Stanek, K. Z.; Salvo, C. Araya; Beatty, T. G.; Bird, J. C. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Denney, K. D. [Marie Curie Fellow at the Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, One Park Place South SE, Suite 700, Atlanta, GA 30303 (United States); Sergeev, S. G.; Borman, G. A. [Crimean Astrophysical Observatory, P/O Nauchny Crimea 98409 (Ukraine); Kaspi, S. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Minezaki, T. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1, Osawa, Mitaka, 181-0015, Tokyo (Japan); Siverd, R. [Department of Physics and Astronomy, Vanderbilt University, 5301 Stevenson Center, Nashville, TN 37235 (United States); Bord, D. J. [Department of Natural Sciences, The University of Michigan-Dearborn, 4901 Evergreen Road, Dearborn, MI 48128 (United States); Che, X. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 41809 (United States); and others

    2012-08-10

    We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were collected at several observatories over a 140 day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for Mrk 335, Mrk 1501, 3C 120, Mrk 6, and PG 2130+099, from which we have measured the time lag between variations in the 5100 A continuum and the H{beta} broad emission line. We then used these measurements to calculate the mass of the supermassive black hole at the center of each of these galaxies. Our new measurements substantially improve previous measurements of M{sub BH} and the size of the broad line-emitting region for four sources and add a measurement for one new object. Our new measurements are consistent with photoionization physics regulating the location of the broad line region in active galactic nuclei.

  7. REVERBERATION MAPPING RESULTS FOR FIVE SEYFERT 1 GALAXIES

    International Nuclear Information System (INIS)

    Grier, C. J.; Peterson, B. M.; Pogge, R. W.; Martini, Paul; Zu, Y.; Kochanek, C. S.; Shappee, B.; Stanek, K. Z.; Salvo, C. Araya; Beatty, T. G.; Bird, J. C.; Denney, K. D.; Bentz, M. C.; Sergeev, S. G.; Borman, G. A.; Kaspi, S.; Minezaki, T.; Siverd, R.; Bord, D. J.; Che, X.

    2012-01-01

    We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were collected at several observatories over a 140 day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for Mrk 335, Mrk 1501, 3C 120, Mrk 6, and PG 2130+099, from which we have measured the time lag between variations in the 5100 Å continuum and the Hβ broad emission line. We then used these measurements to calculate the mass of the supermassive black hole at the center of each of these galaxies. Our new measurements substantially improve previous measurements of M BH and the size of the broad line-emitting region for four sources and add a measurement for one new object. Our new measurements are consistent with photoionization physics regulating the location of the broad line region in active galactic nuclei.

  8. Reverberation Mapping of the Kepler target KA1858+48

    Science.gov (United States)

    Pei, Liuyi; Barth, A. J.; Malkan, M. A.; Cenko, S. B.; Clubb, K. I.; Filippenko, A. V.; Gates, E. L.; Horst, J.; Joner, M. D.; Leonard, D. C.; Sand, D. J.

    2013-01-01

    KA1858+48 is a Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies being monitored by the Kepler mission. We have carried out a reverberation mapping program designed to measure the broad-line region size and estimate the mass of the black hole in KA1858+48. We obtained spectroscopic data using the Kast Spectrograph at the Lick 3 m telescope during dark runs from late winter through fall of 2012, by requesting an observation on each night that the Kast Spectrograph was mounted on the telescope. We also obtained V-band images from the Nickel 1 m telescope at Lick Observatory, the 0.9 m telescope at Brigham Young University West Mountain Observatory, the Faulkes Telescope North at the Las Cumbres Observatory Global Telescope, the KAIT telescope at Lick Observatory, and the 1 m telescope at Mt. Laguna Observatory. The H-beta light curve shows a lag time of approximately 12 days with respect to the V-band continuum flux variations. We will present the continuum and emission-line light curves, cross-correlation lag measurements, and a preliminary estimate of the black hole mass in KA1858+48.

  9. Analysis of P and Pdiff Coda Arrivals for Water Reverberations to Evaluate Shallow Slip Extent in Large Megathrust Earthquakes

    Science.gov (United States)

    Rhode, A.; Lay, T.

    2017-12-01

    Determining the up-dip rupture extent of large megathrust ruptures is important for understanding their tsunami excitation, frictional properties of the shallow megathrust, and potential for separate tsunami earthquake occurrence. On land geodetic data have almost no resolution of the up-dip extent of faulting and teleseismic observations have limited resolution that is strongly influenced by typically poorly known shallow seismic velocity structure near the toe of the accretionary prism. The increase in ocean depth as slip on the megathrust approaches the trench has significant influence on the strength and azimuthal distribution of water reverberations in the far-field P wave coda. For broadband P waves from large earthquakes with dominant signal periods of about 10 s, water reverberations generated by shallow fault slip under deep water may persist for over a minute after the direct P phases have passed, giving a clear signal of slip near the trench. As the coda waves can be quickly evaluated following the P signal, recognition of slip extending to the trench and associated enhanced tsunamigenic potential could be achieved within a few minutes after the P arrival, potentially contributing to rapid tsunami hazard assessment. We examine the broadband P wave coda at distances from 80 to 120° for a large number of recent major and great earthquakes with independently determined slip distributions and known tsunami excitation to evaluate the prospect for rapidly constraining up-dip rupture extent of large megathrust earthquakes. Events known to have significant shallow slip, at least locally extending to the trench (e.g., 2016 Illapel, Chile; 2010 Maule, 2010 Mentawai) do have relatively enhanced coda levels at all azimuths, whereas events that do not rupture the shallow megathrust (e.g., 2007 Sumatra, 2014 Iquique, 2003 Hokkaido) do not. Some events with slip models lacking shallow slip show strong coda generation, raising questions about the up-dip resolution of

  10. Sound intensity

    DEFF Research Database (Denmark)

    Crocker, Malcolm J.; Jacobsen, Finn

    1998-01-01

    This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique.......This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique....

  11. Sound Intensity

    DEFF Research Database (Denmark)

    Crocker, M.J.; Jacobsen, Finn

    1997-01-01

    This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique.......This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique....

  12. Auralization of airborne sound insulation including the influence of source room

    DEFF Research Database (Denmark)

    Rindel, Jens Holger

    2006-01-01

    The paper describes a simple and acoustically accurate method for the auralization of airborne sound insulation between two rooms by means of a room acoustic simulation software (ODEON). The method makes use of a frequency independent transparency of the transmitting surface combined...... with a frequency dependent power setting of the source in the source room. The acoustic properties in terms of volume and reverberation time as well as the area of the transmitting surface are all included in the simulation. The user only has to select the position of the source in the source room and the receiver...... of the transmitting surface is used for the simulation of sound transmission. Also the reduced clarity of the auralization due to the reverberance of the source room is inherent in the method. Currently the method is restricted to transmission loss data in octave bands....

  13. The effect of interaural-level-difference fluctuations on the externalization of sound

    DEFF Research Database (Denmark)

    Catic, Jasmina; Santurette, Sébastien; Buchholz, Jörg M.

    2013-01-01

    Real-world sound sources are usually perceived as externalized and thus properly localized in both direction and distance. This is largely due to (1) the acoustic filtering by the head, torso, and pinna, resulting in modifications of the signal spectrum and thereby a frequency-dependent shaping...... of interaural cues and (2) interaural cues provided by the reverberation inside an enclosed space. This study first investigated the effect of room reverberation on the spectro-temporal behavior of interaural level differences (ILDs) by analyzing dummy-head recordings of speech played at different distances...... in a standard listening room. Next, the effect of ILD fluctuations on the degree of externalization was investigated in a psychoacoustic experiment performed in the same listening room. Individual binaural impulse responses were used to simulate a distant sound source delivered via headphones. The ILDs were...

  14. Sound Spectrum Influences Auditory Distance Perception of Sound Sources Located in a Room Environment

    Directory of Open Access Journals (Sweden)

    Ignacio Spiousas

    2017-06-01

    Full Text Available Previous studies on the effect of spectral content on auditory distance perception (ADP focused on the physically measurable cues occurring either in the near field (low-pass filtering due to head diffraction or when the sound travels distances >15 m (high-frequency energy losses due to air absorption. Here, we study how the spectrum of a sound arriving from a source located in a reverberant room at intermediate distances (1–6 m influences the perception of the distance to the source. First, we conducted an ADP experiment using pure tones (the simplest possible spectrum of frequencies 0.5, 1, 2, and 4 kHz. Then, we performed a second ADP experiment with stimuli consisting of continuous broadband and bandpass-filtered (with center frequencies of 0.5, 1.5, and 4 kHz and bandwidths of 1/12, 1/3, and 1.5 octave pink-noise clips. Our results showed an effect of the stimulus frequency on the perceived distance both for pure tones and filtered noise bands: ADP was less accurate for stimuli containing energy only in the low-frequency range. Analysis of the frequency response of the room showed that the low accuracy observed for low-frequency stimuli can be explained by the presence of sparse modal resonances in the low-frequency region of the spectrum, which induced a non-monotonic relationship between binaural intensity and source distance. The results obtained in the second experiment suggest that ADP can also be affected by stimulus bandwidth but in a less straightforward way (i.e., depending on the center frequency, increasing stimulus bandwidth could have different effects. Finally, the analysis of the acoustical cues suggests that listeners judged source distance using mainly changes in the overall intensity of the auditory stimulus with distance rather than the direct-to-reverberant energy ratio, even for low-frequency noise bands (which typically induce high amount of reverberation. The results obtained in this study show that, depending on

  15. Controlling sound with acoustic metamaterials

    DEFF Research Database (Denmark)

    Cummer, Steven A. ; Christensen, Johan; Alù, Andrea

    2016-01-01

    Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales....... The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create......-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview...

  16. Sound Propagation An impedance Based Approach

    CERN Document Server

    Kim, Yang-Hann

    2010-01-01

    In Sound Propagation: An Impedance Based Approach , Professor Yang-Hann Kim introduces acoustics and sound fields by using the concept of impedance. Kim starts with vibrations and waves, demonstrating how vibration can be envisaged as a kind of wave, mathematically and physically. One-dimensional waves are used to convey the fundamental concepts. Readers can then understand wave propagation in terms of characteristic and driving point impedance. The essential measures for acoustic waves, such as dB scale, octave scale, acoustic pressure, energy, and intensity, are explained. These measures are

  17. Aging and Temporal Influences on Speech Perception in Reverberation and Noise.

    Science.gov (United States)

    Helfer, Karen S.

    The present study examined the interactions of age, temporal resolution, hearing loss, and consonant perception under realistic listening conditions. Four subject groups were employed, with N = 8 per group: young adults with normal hearing or sloping sensorineural hearing loss; and elderly individuals with minimal peripheral hearing loss or presbycusis. Copies of the CUNY Nonsense Syllable Test (NST) were re-recorded under four levels of reverberation in quiet and in +10 signal-to-noise ratio of cafeteria noise. The test stimuli were presented binaurally to the subjects via TDH-49 headphones. In addition, a diotic wideband gap detection task, using a 72 dBSPL presentation level, was used as a measure of temporal resolution. Results of the present investigation demonstrated that all other subject groups performed significantly poorer than the young, normal hearing adults. Scores decreased as the amount of distortion increased, although there was very little difference between performance in the two highest reverberation conditions. For reverberation alone, the young, hearing-impaired listeners obtained the lowest scores; for reverberation + noise, the older, hearing-impaired subjects performed poorest. Large within-group variability was noted in the size of the gap thresholds, and only the two groups of young subjects differed significantly on this task of temporal resolution. Correlation analyses demonstrated a strong inverse relation between age and performance in reverberation + noise, even when degree of hearing loss was partialed out. Pure -tone average, as well as NST scores in quiet and in noise alone were related strongly to performance in reverberation. Multiple regression analyses demonstrated that nonsense syllable perception in reverberation could be predicted from a combination of age, pure-tone thresholds, scores in quiet and noise, and gap threshold. Gap threshold was the strongest predictor variable for reverberation alone, while the NST score

  18. Sonotropic effects of commercial air transport sound on birds.

    Science.gov (United States)

    1962-03-01

    The Electra sound spectrum contains an audible chirp which appears identical in frequency and wave form to the chirp of field crickets. Field observations strongly indicate the sound of the taxiing Electra exerts an attraction for starlings, and poss...

  19. Reverberation Mapping of the Continuum Source in Active Galactic Nuclei

    Science.gov (United States)

    Fausnaugh, Michael Martin

    I present results from a monitoring campaign of 11 active galactic nuclei (AGN) conducted in Spring of 2014. I use the reverberation mapping method to probe the interior structures of the AGN, specifically the broad line regions (BLRs) and accretion disks. One of these AGN, NGC 5548, was also subject to multi-wavelength (X-ray, UV, optical, and near-IR) monitoring using 25 ground-based telescopes and four space-based facilities. For NGC 5548, I detect lags between the continuum emission at different wavelengths that follow a trend consistent with the prediction for continuum reprocessing by an accretion disk with temperature profile T ∝ R -3/4. However, the lags imply a disk radius that is 3 times larger than the prediction from standard thin-disk models. The lags at wavelengths longer than the Vband are also equal to or greater than the lags of high-ionization-state emission lines (such as HeII lambda1640 and lambda4686), suggesting that the continuum-emitting source is of a physical size comparable to the inner broad-line region. Using optical spectra from the Large Binocular Telescope, I estimate the bias of the interband continuum lags due to BLR emission observed in the filters, and I find that the bias for filters with high levels of BLR contamination (˜20%) can be important for the shortest continuum lags. This likely has a significant impact on the u and U bands owing to Balmer continuum emission. I then develop a new procedure for the internal (night-to-night) calibration of time series spectra that can reach precisions of ˜1 millimagnitude and improves traditional techniques by up to a factor of 5. At this level, other systematic issues (e.g., the nightly sensitivity functions and Fe II contamination) limit the final precision of the observed light curves. Using the new calibration method, I next present the data and first results from the optical spectroscopic monitoring component of the reverberation mapping campaign. Five AGN were sufficiently

  20. Fluid Sounds

    DEFF Research Database (Denmark)

    Explorations and analysis of soundscapes have, since Canadian R. Murray Schafer's work during the early 1970's, developed into various established research - and artistic disciplines. The interest in sonic environments is today present within a broad range of contemporary art projects and in arch......Explorations and analysis of soundscapes have, since Canadian R. Murray Schafer's work during the early 1970's, developed into various established research - and artistic disciplines. The interest in sonic environments is today present within a broad range of contemporary art projects...... and in architectural design. Aesthetics, psychoacoustics, perception, and cognition are all present in this expanding field embracing such categories as soundscape composition, sound art, sonic art, sound design, sound studies and auditory culture. Of greatest significance to the overall field is the investigation...

  1. Sound Settlements

    DEFF Research Database (Denmark)

    Mortensen, Peder Duelund; Hornyanszky, Elisabeth Dalholm; Larsen, Jacob Norvig

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice......Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  2. Second sound tracking system

    Science.gov (United States)

    Yang, Jihee; Ihas, Gary G.; Ekdahl, Dan

    2017-10-01

    It is common that a physical system resonates at a particular frequency, whose frequency depends on physical parameters which may change in time. Often, one would like to automatically track this signal as the frequency changes, measuring, for example, its amplitude. In scientific research, one would also like to utilize the standard methods, such as lock-in amplifiers, to improve the signal to noise ratio. We present a complete He ii second sound system that uses positive feedback to generate a sinusoidal signal of constant amplitude via automatic gain control. This signal is used to produce temperature/entropy waves (second sound) in superfluid helium-4 (He ii). A lock-in amplifier limits the oscillation to a desirable frequency and demodulates the received sound signal. Using this tracking system, a second sound signal probed turbulent decay in He ii. We present results showing that the tracking system is more reliable than those of a conventional fixed frequency method; there is less correlation with temperature (frequency) fluctuation when the tracking system is used.

  3. Photoacoustic Sounds from Meteors.

    Energy Technology Data Exchange (ETDEWEB)

    Spalding, Richard E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tencer, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sweatt, William C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hogan, Roy E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boslough, Mark B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Spurny, Pavel [Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic)

    2015-03-01

    High-speed photometric observations of meteor fireballs have shown that they often produce high-amplitude light oscillations with frequency components in the kHz range, and in some cases exhibit strong millisecond flares. We built a light source with similar characteristics and illuminated various materials in the laboratory, generating audible sounds. Models suggest that light oscillations and pulses can radiatively heat dielectric materials, which in turn conductively heats the surrounding air on millisecond timescales. The sound waves can be heard if the illuminated material is sufficiently close to the observer’s ears. The mechanism described herein may explain many reports of meteors that appear to be audible while they are concurrently visible in the sky and too far away for sound to have propagated to the observer. This photoacoustic (PA) explanation provides an alternative to electrophonic (EP) sounds hypothesized to arise from electromagnetic coupling of plasma oscillation in the meteor wake to natural antennas in the vicinity of an observer.

  4. Evaluation of a reverberation enhancement system installed in a small multi purpose hall

    DEFF Research Database (Denmark)

    Gade, Anders Christian

    1997-01-01

    After design and installation of a reverberation enhancement system in new 400 seat multi purpose hall in Vejle, Denmark. room acoustic measurements and listening tests were performed in order to reveal the objective and subjective performance and limits of such a powerful tool for altering ''room...... acoustic'' properties. The compromises in realistic choice of acoustic parameters for the different settings of the system are described with reference to the natural acoustics and functional needs of the hall in question. Although the enhancement system is capable of increasing the reverberation time...

  5. Sound Settlements

    DEFF Research Database (Denmark)

    Mortensen, Peder Duelund; Hornyanszky, Elisabeth Dalholm; Larsen, Jacob Norvig

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  6. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...

  7. An analysis of collegiate band directors' exposure to sound pressure levels

    Science.gov (United States)

    Roebuck, Nikole Moore

    Noise-induced hearing loss (NIHL) is a significant but unfortunate common occupational hazard. The purpose of the current study was to measure the magnitude of sound pressure levels generated within a collegiate band room and determine if those sound pressure levels are of a magnitude that exceeds the policy standards and recommendations of the Occupational Safety and Health Administration (OSHA), and the National Institute of Occupational Safety and Health (NIOSH). In addition, reverberation times were measured and analyzed in order to determine the appropriateness of acoustical conditions for the band rehearsal environment. Sound pressure measurements were taken from the rehearsal of seven collegiate marching bands. Single sample t test were conducted to compare the sound pressure levels of all bands to the noise exposure standards of OSHA and NIOSH. Multiple regression analysis were conducted and analyzed in order to determine the effect of the band room's conditions on the sound pressure levels and reverberation times. Time weighted averages (TWA), noise percentage doses, and peak levels were also collected. The mean Leq for all band directors was 90.5 dBA. The total accumulated noise percentage dose for all band directors was 77.6% of the maximum allowable daily noise dose under the OSHA standard. The total calculated TWA for all band directors was 88.2% of the maximum allowable daily noise dose under the OSHA standard. The total accumulated noise percentage dose for all band directors was 152.1% of the maximum allowable daily noise dose under the NIOSH standards, and the total calculated TWA for all band directors was 93dBA of the maximum allowable daily noise dose under the NIOSH standard. Multiple regression analysis revealed that the room volume, the level of acoustical treatment and the mean room reverberation time predicted 80% of the variance in sound pressure levels in this study.

  8. Techniques and instrumentation for the measurement of transient sound energy flux

    Science.gov (United States)

    Watkinson, P. S.; Fahy, F. J.

    1983-12-01

    The evaluation of sound intensity distributions, and sound powers, of essentially continuous sources such as automotive engines, electric motors, production line machinery, furnaces, earth moving machinery and various types of process plants were studied. Although such systems are important sources of community disturbance and, to a lesser extent, of industrial health hazard, the most serious sources of hearing hazard in industry are machines operating on an impact principle, such as drop forges, hammers and punches. Controlled experiments to identify major noise source regions and mechanisms are difficult because it is normally impossible to install them in quiet, anechoic environments. The potential for sound intensity measurement to provide a means of overcoming these difficulties has given promising results, indicating the possibility of separation of directly radiated and reverberant sound fields. However, because of the complexity of transient sound fields, a fundamental investigation is necessary to establish the practicability of intensity field decomposition, which is basic to source characterization techniques.

  9. Understanding AGNs in the Local Universe through Optical Reverberation Mapping

    Science.gov (United States)

    Pei, Liuyi

    2016-01-01

    I present the results of observational projects aimed at measuring the mass of the black hole at the center of active galactic nuclei (AGNs) and understanding the structure and kinematics of the broad-line emitting gas within the black hole's sphere of influence.The first project aims to measure the black hole mass in the Kepler-field AGN KA1858. We obtained simultaneous spectroscopic data from the Lick Observatory 3-m telescope using the Kast Double Spectrograph and photometry data from five ground-based telescopes, and used reverberation mapping (RM) techniques to measure the emission-line light curves' lags relative to continuum variations. We obtained lags for H-beta, H-gamma, H-delta, and He II, and obtained the first black hole mass measurement for this object. Our results will serve as a reference point for future studies on relations between black hole mass and continuum variability characteristics using Kepler AGN light curves.The second project, in collaboration with the AGN STORM team, aims to understand the structure and dynamics of the broad line region (BLR) in NGC 5548 in both UV and optical wavelengths. To supplement 6 months of HST UV observations, we obtained simultaneous optical spectroscopic data from six ground-based observatories. We obtained emission-line lags for the optical H-beta and He II lines as well as velocity-resolved lag measurements for H-beta. We also compared the velocity-resolved lags for H-beta to the UV emission lines C IV and Ly-alpha and found similar lag profiles for all three lines.Finally, I will discuss my contributions to two other collaborations in AGN RM. A key component in RM is monitoring continuum variability, which is often done through ground-based photometry. I will present a pipeline that performs aperture photometry on any number of images of an AGN with WCS coordinates and immediately produces relative light curves. This pipeline enables quick looks of AGN variability in real time and has been used in the

  10. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: TECHNICAL OVERVIEW

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States); Hall, Patrick B. [Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 (Canada); McGreer, Ian D.; Fan, Xiaohui [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Anderson, Scott F. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States); Chen, Yuguang [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Denney, Kelly D. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Eftekharzadeh, Sarah [Department of Physics and Astronomy, University of Wyoming, 1000 East University Avenue, Laramie, WY 82071 (United States); Gao, Yang [Department of Engineering Physics and Center for Astrophysics, Tsinghua University, Beijing 100084 (China); Green, Paul J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Horne, Keith [SUPA Physics/Astronomy, University of St. Andrews, St. Andrews KY16 9SS (United Kingdom); Jiang, Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1504 (United States); Kelly, Brandon C. [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93107 (United States); and others

    2015-01-01

    The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is a dedicated multi-object RM experiment that has spectroscopically monitored a sample of 849 broad-line quasars in a single 7 deg{sup 2} field with the SDSS-III Baryon Oscillation Spectroscopic Survey spectrograph. The RM quasar sample is flux-limited to i {sub psf} = 21.7 mag, and covers a redshift range of 0.1 < z < 4.5 without any other cuts on quasar properties. Optical spectroscopy was performed during 2014 January-July dark/gray time, with an average cadence of ∼4 days, totaling more than 30 epochs. Supporting photometric monitoring in the g and i bands was conducted at multiple facilities including the Canada-France-Hawaii Telescope (CFHT) and the Steward Observatory Bok telescope in 2014, with a cadence of ∼2 days and covering all lunar phases. The RM field (R.A., decl. = 14:14:49.00, +53:05:00.0) lies within the CFHT-LS W3 field, and coincides with the Pan-STARRS 1 (PS1) Medium Deep Field MD07, with three prior years of multi-band PS1 light curves. The SDSS-RM six month baseline program aims to detect time lags between the quasar continuum and broad line region (BLR) variability on timescales of up to several months (in the observed frame) for ∼10% of the sample, and to anchor the time baseline for continued monitoring in the future to detect lags on longer timescales and at higher redshift. SDSS-RM is the first major program to systematically explore the potential of RM for broad-line quasars at z > 0.3, and will investigate the prospects of RM with all major broad lines covered in optical spectroscopy. SDSS-RM will provide guidance on future multi-object RM campaigns on larger scales, and is aiming to deliver more than tens of BLR lag detections for a homogeneous sample of quasars. We describe the motivation, design, and implementation of this program, and outline the science impact expected from the resulting data for RM and general quasar science.

  11. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: TECHNICAL OVERVIEW

    International Nuclear Information System (INIS)

    Shen, Yue; Brandt, W. N.; Dawson, Kyle S.; Hall, Patrick B.; McGreer, Ian D.; Fan, Xiaohui; Anderson, Scott F.; Chen, Yuguang; Denney, Kelly D.; Eftekharzadeh, Sarah; Gao, Yang; Green, Paul J.; Greene, Jenny E.; Ho, Luis C.; Horne, Keith; Jiang, Linhua; Kelly, Brandon C.

    2015-01-01

    The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is a dedicated multi-object RM experiment that has spectroscopically monitored a sample of 849 broad-line quasars in a single 7 deg 2 field with the SDSS-III Baryon Oscillation Spectroscopic Survey spectrograph. The RM quasar sample is flux-limited to i psf = 21.7 mag, and covers a redshift range of 0.1 < z < 4.5 without any other cuts on quasar properties. Optical spectroscopy was performed during 2014 January-July dark/gray time, with an average cadence of ∼4 days, totaling more than 30 epochs. Supporting photometric monitoring in the g and i bands was conducted at multiple facilities including the Canada-France-Hawaii Telescope (CFHT) and the Steward Observatory Bok telescope in 2014, with a cadence of ∼2 days and covering all lunar phases. The RM field (R.A., decl. = 14:14:49.00, +53:05:00.0) lies within the CFHT-LS W3 field, and coincides with the Pan-STARRS 1 (PS1) Medium Deep Field MD07, with three prior years of multi-band PS1 light curves. The SDSS-RM six month baseline program aims to detect time lags between the quasar continuum and broad line region (BLR) variability on timescales of up to several months (in the observed frame) for ∼10% of the sample, and to anchor the time baseline for continued monitoring in the future to detect lags on longer timescales and at higher redshift. SDSS-RM is the first major program to systematically explore the potential of RM for broad-line quasars at z > 0.3, and will investigate the prospects of RM with all major broad lines covered in optical spectroscopy. SDSS-RM will provide guidance on future multi-object RM campaigns on larger scales, and is aiming to deliver more than tens of BLR lag detections for a homogeneous sample of quasars. We describe the motivation, design, and implementation of this program, and outline the science impact expected from the resulting data for RM and general quasar science

  12. Calculation of sound propagation in fibrous materials

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1996-01-01

    Calculations of attenuation and velocity of audible sound waves in glass wools are presented. The calculations use only the diameters of fibres and the mass density of glass wools as parameters. The calculations are compared with measurements.......Calculations of attenuation and velocity of audible sound waves in glass wools are presented. The calculations use only the diameters of fibres and the mass density of glass wools as parameters. The calculations are compared with measurements....

  13. PREFACE: Aerodynamic sound Aerodynamic sound

    Science.gov (United States)

    Akishita, Sadao

    2010-02-01

    The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

  14. Sound Visualisation

    OpenAIRE

    Dolenc, Peter

    2013-01-01

    This thesis contains a description of a construction of subwoofer case that has an extra functionality of being able to produce special visual effects and display visualizations that match the currently playing sound. For this reason, multiple lighting elements made out of LED (Light Emitting Diode) diodes were installed onto the subwoofer case. The lighting elements are controlled by dedicated software that was also developed. The software runs on STM32F4-Discovery evaluation board inside a ...

  15. Sound Clocks and Sonic Relativity

    Science.gov (United States)

    Todd, Scott L.; Menicucci, Nicolas C.

    2017-10-01

    Sound propagation within certain non-relativistic condensed matter models obeys a relativistic wave equation despite such systems admitting entirely non-relativistic descriptions. A natural question that arises upon consideration of this is, "do devices exist that will experience the relativity in these systems?" We describe a thought experiment in which `acoustic observers' possess devices called sound clocks that can be connected to form chains. Careful investigation shows that appropriately constructed chains of stationary and moving sound clocks are perceived by observers on the other chain as undergoing the relativistic phenomena of length contraction and time dilation by the Lorentz factor, γ , with c the speed of sound. Sound clocks within moving chains actually tick less frequently than stationary ones and must be separated by a shorter distance than when stationary to satisfy simultaneity conditions. Stationary sound clocks appear to be length contracted and time dilated to moving observers due to their misunderstanding of their own state of motion with respect to the laboratory. Observers restricted to using sound clocks describe a universe kinematically consistent with the theory of special relativity, despite the preferred frame of their universe in the laboratory. Such devices show promise in further probing analogue relativity models, for example in investigating phenomena that require careful consideration of the proper time elapsed for observers.

  16. Sound localization and occupational noise

    Directory of Open Access Journals (Sweden)

    Pedro de Lemos Menezes

    2014-02-01

    Full Text Available OBJECTIVE: The aim of this study was to determine the effects of occupational noise on sound localization in different spatial planes and frequencies among normal hearing firefighters. METHOD: A total of 29 adults with pure-tone hearing thresholds below 25 dB took part in the study. The participants were divided into a group of 19 firefighters exposed to occupational noise and a control group of 10 adults who were not exposed to such noise. All subjects were assigned a sound localization task involving 117 stimuli from 13 sound sources that were spatially distributed in horizontal, vertical, midsagittal and transverse planes. The three stimuli, which were square waves with fundamental frequencies of 500, 2,000 and 4,000 Hz, were presented at a sound level of 70 dB and were randomly repeated three times from each sound source. The angle between the speaker's axis in the same plane was 45°, and the distance to the subject was 1 m. RESULT: The results demonstrate that the sound localization ability of the firefighters was significantly lower (p<0.01 than that of the control group. CONCLUSION: Exposure to occupational noise, even when not resulting in hearing loss, may lead to a diminished ability to locate a sound source.

  17. The use of a reference absorber for absorption measurements in a reverberation chamber

    DEFF Research Database (Denmark)

    Nolan, Melanie; Vercammen, Martijn; Jeong, Cheol-Ho

    2014-01-01

    The statistical incidence absorption coefficient is measured in a reverberation room according to ISO 354. This absorption coefficient is referred to as Sabine absorption coefficient, which assumes the chambe r to be completely diffuse. It is known that the reproducibility of these results is poo...

  18. Impacts of Reverberation Time, Absorption Location and Background Noise on Listening Conditions in Multi Source Environment

    DEFF Research Database (Denmark)

    Saher, Konca; Rindel, Jens Holger; Nijs, Lau

    2005-01-01

    index (STI) needs to be improved. The impact of the reverberation time (RT), the distribution of the absorptive materials and the introduction of a screen on STI are discussed briefly .However, these objective parameters have to be assessed through subjective judgement. Auralizations of the multi source...

  19. Exploiting deep neural networks and head movements for binaural localisation of multiple speakers in reverberant conditions

    DEFF Research Database (Denmark)

    Ma, Ning; Brown, Guy J.; May, Tobias

    2015-01-01

    This paper presents a novel machine-hearing system that exploits deep neural networks (DNNs) and head movements for binaural localisation of multiple speakers in reverberant conditions. DNNs are used to map binaural features, consisting of the complete crosscorrelation function (CCF) and interaural...

  20. Assessment of reverberation time by two measurement systems for room electromagnetics analysis

    DEFF Research Database (Denmark)

    Bamba, Aliou; Joseph, Wout; Plets, David

    2011-01-01

    A closed room environment is viewed as a lossy cavity, characterized by possibly a line of sight (LOS) component and diffuse scattering parts from walls and internal obstacles. A theory used in acoustics and reverberation chambers is applied for the electromagnetics case, and main issues related...

  1. Echo and reverberation in a Pekeris waveguide by convolution and by the product rule

    NARCIS (Netherlands)

    Ainslie, M.A.

    2013-01-01

    The detection performance of an active sonar depends on the intensity of the signal (target echo) relative to that of a background of reverberation plus noise. The echo is calculated for a standard test problem by convolving the time-domain impulse response at the target position with itself. The

  2. Do wavelet filters provide more accurate estimates of reverberation times at low frequencies

    DEFF Research Database (Denmark)

    Sobreira Seoane, Manuel A.; Pérez Cabo, David; Agerkvist, Finn T.

    2016-01-01

    It has been amply demonstrated in the literature that it is not possible to measure acoustic decays without significant errors for low BT values (narrow filters and or low reverberation times). Recently, it has been shown how the main source of distortion in the time envelope of the acoustic deca...

  3. Sound absorption coefficient of coal bottom ash concrete for railway application

    Science.gov (United States)

    Ramzi Hannan, N. I. R.; Shahidan, S.; Maarof, Z.; Ali, N.; Abdullah, S. R.; Ibrahim, M. H. Wan

    2017-11-01

    A porous concrete able to reduce the sound wave that pass through it. When a sound waves strike a material, a portion of the sound energy was reflected back and another portion of the sound energy was absorbed by the material while the rest was transmitted. The larger portion of the sound wave being absorbed, the lower the noise level able to be lowered. This study is to investigate the sound absorption coefficient of coal bottom ash (CBA) concrete compared to the sound absorption coefficient of normal concrete by carried out the impedance tube test. Hence, this paper presents the result of the impedance tube test of the CBA concrete and normal concrete.

  4. Sound Beams with Shockwave Pulses

    Science.gov (United States)

    Enflo, B. O.

    2000-11-01

    The beam equation for a sound beam in a diffusive medium, called the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, has a class of solutions, which are power series in the transverse variable with the terms given by a solution of a generalized Burgers’ equation. A free parameter in this generalized Burgers’ equation can be chosen so that the equation describes an N-wave which does not decay. If the beam source has the form of a spherical cap, then a beam with a preserved shock can be prepared. This is done by satisfying an inequality containing the spherical radius, the N-wave pulse duration, the N-wave pulse amplitude, and the sound velocity in the fluid.

  5. Multi-time-scale X-ray reverberation mapping of accreting black holes

    Science.gov (United States)

    Mastroserio, Guglielmo; Ingram, Adam; van der Klis, Michiel

    2018-04-01

    Accreting black holes show characteristic reflection features in their X-ray spectrum, including an iron Kα line, resulting from hard X-ray continuum photons illuminating the accretion disc. The reverberation lag resulting from the path-length difference between direct and reflected emission provides a powerful tool to probe the innermost regions around both stellar-mass and supermassive black holes. Here, we present for the first time a reverberation mapping formalism that enables modelling of energy-dependent time lags and variability amplitude for a wide range of variability time-scales, taking the complete information of the cross-spectrum into account. We use a pivoting power-law model to account for the spectral variability of the continuum that dominates over the reverberation lags for longer time-scale variability. We use an analytic approximation to self-consistently account for the non-linear effects caused by this continuum spectral variability, which have been ignored by all previous reverberation studies. We find that ignoring these non-linear effects can bias measurements of the reverberation lags, particularly at low frequencies. Since our model is analytic, we are able to fit simultaneously for a wide range of Fourier frequencies without prohibitive computational expense. We also introduce a formalism of fitting to real and imaginary parts of our cross-spectrum statistic, which naturally avoids some mistakes/inaccuracies previously common in the literature. We perform proof-of-principle fits to Rossi X-ray Timing Explorer data of Cygnus X-1.

  6. Evaluation of Sound Quality, Boominess and Boxiness in Small Rooms

    DEFF Research Database (Denmark)

    Weisser, Adam; Rindel, Jens Holger

    2006-01-01

    ratings. The classical bass ratio definitions showed poor correlation with all subjective ratings. The overall sound quality ratings gave different results for speech and music. For speech the preferred mean RT should be as low as possible, whereas for music there was found a preferred range between 0......The acoustics of small rooms has been studied with emphasis on sound quality, boominess and boxiness when the rooms are used for speech or music. Seven rooms with very different characteristics have been used for the study. Subjective listening tests were made using binaural recordings...... of reproduced speech and music. The test results were compared with a large number of objective acoustic parameters based on the frequency-dependent reverberation times measured in the rooms. This has led to the proposal of three new acoustic parameters, which have shown high correlation with the subjective...

  7. Mid-Frequency Reverberation Measurements with Full Companion Environmental Support

    Science.gov (United States)

    2014-12-30

    independent sound speed extracted from this CTD profile. The rays are named bottom-turn (BT), turn-bottom (TB), turn-bottom-turn ( TBT ), and surface-bottom...by travel time) with the rays of Fig. 3(b). The correspondence is #3 BT, #4 TB, #5 TBT , and #6 SBS. The oscillations in arrival time around 16:30...one bottom bounce between them ( TBT ). Arrival #6 is a ray bouncing twice at the sea surface and once at the bottom (SBS). The arrivals in Fig. 4 have a

  8. Fascinating World of Shock Waves

    Indian Academy of Sciences (India)

    Srimath

    travelling at supersonic speeds (more than the sound speed at ... actual earth- quake, travel at supersonic speeds. .... The time scale of the shock wave is also important ..... real lithotripsy where a shock wave is used shatter the kidney stones!

  9. Magnetospheric radio sounding

    International Nuclear Information System (INIS)

    Ondoh, Tadanori; Nakamura, Yoshikatsu; Koseki, Teruo; Watanabe, Sigeaki; Murakami, Toshimitsu

    1977-01-01

    Radio sounding of the plasmapause from a geostationary satellite has been investigated to observe time variations of the plasmapause structure and effects of the plasma convection. In the equatorial plane, the plasmapause is located, on the average, at 4 R sub(E) (R sub(E); Earth radius), and the plasma density drops outwards from 10 2 -10 3 /cm 3 to 1-10/cm 3 in the plasmapause width of about 600 km. Plasmagrams showing a relation between the virtual range and sounding frequencies are computed by ray tracing of LF-VLF waves transmitted from a geostationary satellite, using model distributions of the electron density in the vicinity of the plasmapause. The general features of the plasmagrams are similar to the topside ionograms. The plasmagram has no penetration frequency such as f 0 F 2 , but the virtual range of the plasmagram increases rapidly with frequency above 100 kHz, since the distance between a satellite and wave reflection point increases rapidly with increasing the electron density inside the plasmapause. The plasmapause sounder on a geostationary satellite has been designed by taking account of an average propagation distance of 2 x 2.6 R sub(E) between a satellite (6.6 R sub(E)) and the plasmapause (4.0 R sub(E)), background noise, range resolution, power consumption, and receiver S/N of 10 dB. The 13-bit Barker coded pulses of baud length of 0.5 msec should be transmitted in direction parallel to the orbital plane at frequencies for 10 kHz-2MHz in a pulse interval of 0.5 sec. The transmitter peak power of 70 watts and 700 watts are required respectively in geomagnetically quiet and disturbed (strong nonthermal continuum emissions) conditions for a 400 meter cylindrical dipole of 1.2 cm diameter on the geostationary satellite. This technique will open new area of radio sounding in the magnetosphere. (auth.)

  10. Leading edge effect in laminar boundary layer excitation by sound

    International Nuclear Information System (INIS)

    Leehey, P.; Shapiro, P.

    1980-01-01

    Essentially plane pure tone sound waves were directed downstream over a heavily damped smooth flat plate installed in a low turbulence (0.04%) subsonic wind tunnel. Laminar boundary layer disturbance growth rates were measured with and without sound excitation and compared with numerical results from spatial stability theory. The data indicate that the sound field and Tollmien-Schlichting (T-S) waves coexist with comparable amplitudes when the latter are damped; moreover, the response is linear. Higher early growth rates occur for excitation by sound than by stream turbulence. Theoretical considerations indicate that the boundary layer is receptive to sound excitation primarily at the test plate leading edge. (orig.)

  11. Making sound vortices by metasurfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Liping; Qiu, Chunyin, E-mail: cyqiu@whu.edu.cn; Lu, Jiuyang; Tang, Kun; Ke, Manzhu; Peng, Shasha [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Jia, Han [State Key Laboratory of Acoustics and Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Zhengyou [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Institute for Advanced Studies, Wuhan University, Wuhan 430072 (China)

    2016-08-15

    Based on the Huygens-Fresnel principle, a metasurface structure is designed to generate a sound vortex beam in airborne environment. The metasurface is constructed by a thin planar plate perforated with a circular array of deep subwavelength resonators with desired phase and amplitude responses. The metasurface approach in making sound vortices is validated well by full-wave simulations and experimental measurements. Potential applications of such artificial spiral beams can be anticipated, as exemplified experimentally by the torque effect exerting on an absorbing disk.

  12. Statistics of natural binaural sounds.

    Directory of Open Access Journals (Sweden)

    Wiktor Młynarski

    Full Text Available Binaural sound localization is usually considered a discrimination task, where interaural phase (IPD and level (ILD disparities at narrowly tuned frequency channels are utilized to identify a position of a sound source. In natural conditions however, binaural circuits are exposed to a stimulation by sound waves originating from multiple, often moving and overlapping sources. Therefore statistics of binaural cues depend on acoustic properties and the spatial configuration of the environment. Distribution of cues encountered naturally and their dependence on physical properties of an auditory scene have not been studied before. In the present work we analyzed statistics of naturally encountered binaural sounds. We performed binaural recordings of three auditory scenes with varying spatial configuration and analyzed empirical cue distributions from each scene. We have found that certain properties such as the spread of IPD distributions as well as an overall shape of ILD distributions do not vary strongly between different auditory scenes. Moreover, we found that ILD distributions vary much weaker across frequency channels and IPDs often attain much higher values, than can be predicted from head filtering properties. In order to understand the complexity of the binaural hearing task in the natural environment, sound waveforms were analyzed by performing Independent Component Analysis (ICA. Properties of learned basis functions indicate that in natural conditions soundwaves in each ear are predominantly generated by independent sources. This implies that the real-world sound localization must rely on mechanisms more complex than a mere cue extraction.

  13. Statistics of natural binaural sounds.

    Science.gov (United States)

    Młynarski, Wiktor; Jost, Jürgen

    2014-01-01

    Binaural sound localization is usually considered a discrimination task, where interaural phase (IPD) and level (ILD) disparities at narrowly tuned frequency channels are utilized to identify a position of a sound source. In natural conditions however, binaural circuits are exposed to a stimulation by sound waves originating from multiple, often moving and overlapping sources. Therefore statistics of binaural cues depend on acoustic properties and the spatial configuration of the environment. Distribution of cues encountered naturally and their dependence on physical properties of an auditory scene have not been studied before. In the present work we analyzed statistics of naturally encountered binaural sounds. We performed binaural recordings of three auditory scenes with varying spatial configuration and analyzed empirical cue distributions from each scene. We have found that certain properties such as the spread of IPD distributions as well as an overall shape of ILD distributions do not vary strongly between different auditory scenes. Moreover, we found that ILD distributions vary much weaker across frequency channels and IPDs often attain much higher values, than can be predicted from head filtering properties. In order to understand the complexity of the binaural hearing task in the natural environment, sound waveforms were analyzed by performing Independent Component Analysis (ICA). Properties of learned basis functions indicate that in natural conditions soundwaves in each ear are predominantly generated by independent sources. This implies that the real-world sound localization must rely on mechanisms more complex than a mere cue extraction.

  14. Time domain acoustic contrast control implementation of sound zones for low-frequency input signals

    DEFF Research Database (Denmark)

    Schellekens, Daan H. M.; Møller, Martin Bo; Olsen, Martin

    2016-01-01

    Sound zones are two or more regions within a listening space where listeners are provided with personal audio. Acoustic contrast control (ACC) is a sound zoning method that maximizes the average squared sound pressure in one zone constrained to constant pressure in other zones. State......-of-the-art time domain broadband acoustic contrast control (BACC) methods are designed for anechoic environments. These methods are not able to realize a flat frequency response in a limited frequency range within a reverberant environment. Sound field control in a limited frequency range is a requirement...... to accommodate the effective working range of the loudspeakers. In this paper, a new BACC method is proposed which results in an implementation realizing a flat frequency response in the target zone. This method is applied in a bandlimited low-frequency scenario where the loudspeaker layout surrounds two...

  15. Sound knowledge

    DEFF Research Database (Denmark)

    Kauffmann, Lene Teglhus

    as knowledge based on reflexive practices. I chose ‘health promotion’ as the field for my research as it utilises knowledge produced in several research disciplines, among these both quantitative and qualitative. I mapped out the institutions, actors, events, and documents that constituted the field of health...... of the research is to investigate what is considered to ‘work as evidence’ in health promotion and how the ‘evidence discourse’ influences social practices in policymaking and in research. From investigating knowledge practices in the field of health promotion, I develop the concept of sound knowledge...... result of a rigorous and standardized research method. However, this anthropological analysis shows that evidence and evidence-based is a hegemonic ‘way of knowing’ that sometimes transposes everyday reasoning into an epistemological form. However, the empirical material shows a variety of understandings...

  16. Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes

    International Nuclear Information System (INIS)

    Radicke, Marcus

    2009-01-01

    The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm 2 and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [de

  17. Waves in strong centrifugal fields: dissipationless gas

    Science.gov (United States)

    Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.

    2015-04-01

    Linear waves are investigated in a rotating gas under the condition of strong centrifugal acceleration of the order 106 g realized in gas centrifuges for separation of uranium isotopes. Sound waves split into three families of the waves under these conditions. Dispersion equations are obtained. The characteristics of the waves strongly differ from the conventional sound waves on polarization, velocity of propagation and distribution of energy of the waves in space for two families having frequencies above and below the frequency of the conventional sound waves. The energy of these waves is localized in rarefied region of the gas. The waves of the third family were not specified before. They propagate exactly along the rotational axis with the conventional sound velocity. These waves are polarized only along the rotational axis. Radial and azimuthal motions are not excited. Energy of the waves is concentrated near the wall of the rotor where the density of the gas is largest.

  18. PULSAR.MAKING VISIBLE THE SOUND OF STARS

    OpenAIRE

    Lega, Ferran

    2015-01-01

    [EN] Pulsar, making visible the sound of stars is a comunication based on a sound Installation raised as a site-specific project to show the hidden abilities of sound to generate images and patterns on the matter, using the acoustic science of cymatics. The objective of this communication will show people how through abstract and intangible sounds from celestial orbs of cosmos (radio waves generated by electromagnetic pulses from the rotation of neutrón stars), we can create ar...

  19. DRI internal Wave Simulations

    National Research Council Canada - National Science Library

    Reynolds, Stephen A; Levine, Murray D

    2005-01-01

    .... A processing module is developed that takes profile estimates as input and uses numerically simulated linear internal wave displacements to create two-dimensional range-dependent sound speed fields...

  20. Sound Search Engine Concept

    DEFF Research Database (Denmark)

    2006-01-01

    Sound search is provided by the major search engines, however, indexing is text based, not sound based. We will establish a dedicated sound search services with based on sound feature indexing. The current demo shows the concept of the sound search engine. The first engine will be realased June...

  1. The effects of reverberant self- and overlap-masking on speech recognition in cochlear implant listeners.

    Science.gov (United States)

    Desmond, Jill M; Collins, Leslie M; Throckmorton, Chandra S

    2014-06-01

    Many cochlear implant (CI) listeners experience decreased speech recognition in reverberant environments [Kokkinakis et al., J. Acoust. Soc. Am. 129(5), 3221-3232 (2011)], which may be caused by a combination of self- and overlap-masking [Bolt and MacDonald, J. Acoust. Soc. Am. 21(6), 577-580 (1949)]. Determining the extent to which these effects decrease speech recognition for CI listeners may influence reverberation mitigation algorithms. This study compared speech recognition with ideal self-masking mitigation, with ideal overlap-masking mitigation, and with no mitigation. Under these conditions, mitigating either self- or overlap-masking resulted in significant improvements in speech recognition for both normal hearing subjects utilizing an acoustic model and for CI listeners using their own devices.

  2. REVERBERATION MAPPING MEASUREMENTS OF BLACK HOLE MASSES IN SIX LOCAL SEYFERT GALAXIES

    International Nuclear Information System (INIS)

    Denney, K. D.; Peterson, B. M.; Pogge, R. W.; Atlee, D. W.; Bentz, M. C.; Bird, J. C.; Comins, M. L.; Dietrich, M.; Eastman, J. D.; Adair, A.; Au-Yong, K.; Chisholm, E.; Ewald, S.; Ferbey, S.; Jackson, K.; Brokofsky, D. J.; Gaskell, C. M.; Hedrick, C. H.; Doroshenko, V. T.; Efimov, Y. S.

    2010-01-01

    We present the final results from a high sampling rate, multi-month, spectrophotometric reverberation mapping campaign undertaken to obtain either new or improved Hβ reverberation lag measurements for several relatively low-luminosity active galactic nuclei (AGNs). We have reliably measured the time delay between variations in the continuum and Hβ emission line in six local Seyfert 1 galaxies. These measurements are used to calculate the mass of the supermassive black hole at the center of each of these AGNs. We place our results in context to the most current calibration of the broad-line region (BLR) R BLR -L relationship, where our results remove outliers and reduce the scatter at the low-luminosity end of this relationship. We also present velocity-resolved Hβ time-delay measurements for our complete sample, though the clearest velocity-resolved kinematic signatures have already been published.

  3. REVERBERATION AND PHOTOIONIZATION ESTIMATES OF THE BROAD-LINE REGION RADIUS IN LOW-z QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Negrete, C. Alenka [Instituto Nacional de Astrofisica, Optica y Electronica (Mexico); Dultzin, Deborah [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (Mexico); Marziani, Paola [INAF, Astronomical Observatory of Padova, I-35122 Padova (Italy); Sulentic, Jack W., E-mail: cnegrete@inaoep.mx, E-mail: deborah@astro.unam.mx, E-mail: paola.marziani@oapd.inaf.it, E-mail: sulentic@iaa.es [Instituto de Astrofisica de Andalucia, E-18008 Granada (Spain)

    2013-07-01

    Black hole mass estimation in quasars, especially at high redshift, involves the use of single-epoch spectra with signal-to-noise ratio and resolution that permit accurate measurement of the width of a broad line assumed to be a reliable virial estimator. Coupled with an estimate of the radius of the broad-line region (BLR) this yields the black hole mass M{sub BH}. The radius of the BLR may be inferred from an extrapolation of the correlation between source luminosity and reverberation-derived r{sub BLR} measures (the so-called Kaspi relation involving about 60 low-z sources). We are exploring a different method for estimating r{sub BLR} directly from inferred physical conditions in the BLR of each source. We report here on a comparison of r{sub BLR} estimates that come from our method and from reverberation mapping. Our ''photoionization'' method employs diagnostic line intensity ratios in the rest-frame range 1400-2000 A (Al III {lambda}1860/Si III] {lambda}1892, C IV {lambda}1549/Al III {lambda}1860) that enable derivation of the product of density and ionization parameter with the BLR distance derived from the definition of the ionization parameter. We find good agreement between our estimates of the density, ionization parameter, and r{sub BLR} and those from reverberation mapping. We suggest empirical corrections to improve the agreement between individual photoionization-derived r{sub BLR} values and those obtained from reverberation mapping. The results in this paper can be exploited to estimate M{sub BH} for large samples of high-z quasars using an appropriate virial broadening estimator. We show that the width of the UV intermediate emission lines are consistent with the width of H{beta}, thereby providing a reliable virial broadening estimator that can be measured in large samples of high-z quasars.

  4. TRACING THE REVERBERATION LAG IN THE HARD STATE OF BLACK HOLE X-RAY BINARIES

    International Nuclear Information System (INIS)

    De Marco, B.; Ponti, G.; Nandra, K.; Muñoz-Darias, T.

    2015-01-01

    We report results obtained from a systematic analysis of X-ray lags in a sample of black hole X-ray binaries, with the aim of assessing the presence of reverberation lags and studying their evolution during outburst. We used XMM-Newton and simultaneous Rossi X-ray Timing Explorer (RXTE) observations to obtain broadband energy coverage of both the disk and the hard X-ray Comptonization components. In most cases the detection of reverberation lags is hampered by low levels of variability-power signal-to-noise ratio (typically when the source is in a soft state) and/or short exposure times. The most detailed study was possible for GX 339-4 in the hard state, which allowed us to characterize the evolution of X-ray lags as a function of luminosity in a single source. Over all the sampled frequencies (∼0.05–9 Hz), we observe the hard lags intrinsic to the power-law component, already well known from previous RXTE studies. The XMM-Newton soft X-ray response allows us to detail the disk variability. At low frequencies (long timescales) the disk component always leads the power-law component. On the other hand, a soft reverberation lag (ascribable to thermal reprocessing) is always detected at high frequencies (short timescales). The intrinsic amplitude of the reverberation lag decreases as the source luminosity and the disk fraction increase. This suggests that the distance between the X-ray source and the region of the optically thick disk where reprocessing occurs gradually decreases as GX 339-4 rises in luminosity through the hard state, possibly as a consequence of reduced disk truncation

  5. PyCCF: Python Cross Correlation Function for reverberation mapping studies

    Science.gov (United States)

    Sun, Mouyuan; Grier, C. J.; Peterson, B. M.

    2018-05-01

    PyCCF emulates a Fortran program written by B. Peterson for use with reverberation mapping. The code cross correlates two light curves that are unevenly sampled using linear interpolation and measures the peak and centroid of the cross-correlation function. In addition, it is possible to run Monto Carlo iterations using flux randomization and random subset selection (RSS) to produce cross-correlation centroid distributions to estimate the uncertainties in the cross correlation results.

  6. Bulk damping of sound in superfluid 3He--4He under stagnation of the normal component

    International Nuclear Information System (INIS)

    Karchava, T.A.; Sanikidze, D.G.; Chkhaidze, N.D.

    1983-01-01

    The propagation of waves in superfluid 3 He-- 4 He solutions is considered under partial stagnation of the normal component. The wave processes in capillaries are presented as a superposition of the first sound, second sound, and viscous and diffusion waves. The damping coefficients are calculated for the modified first sound and for the thermal wave in superfluid 3 He-- 4 He solutions and related to the viscosity, thermal conductivity, diffusion, barodiffusion, and thermodiffusion coefficients

  7. A REVERBERATION-BASED BLACK HOLE MASS FOR MCG-06-30-15

    International Nuclear Information System (INIS)

    Bentz, Misty C.; Crenshaw, D. Michael; Ou-Yang, Benjamin; Cackett, Edward M.; Horne, Keith; Street, Rachel

    2016-01-01

    We present the results of a reverberation campaign targeting MGC-06-30-15. Spectrophotometric monitoring and broad-band photometric monitoring over the course of four months in spring 2012 allowed a determination of a time delay in the broad H β emission line of τ = 5.3 ± 1.8 days in the rest frame of the active galactic nucleus (AGN). Combined with the width of the variable portion of the emission line, we determine a black hole mass of M BH = (1.6 ± 0.4) × 10 6 M ⊙ . Both the H β time delay and the black hole mass are in good agreement with expectations from the R BLR – L and M BH – σ ⋆ relationships for other reverberation-mapped AGNs. The H β time delay is also in good agreement with the relationship between H β and broad-band near-IR delays, in which the effective size of the broad-line region is ∼4–5 times smaller than the inner edge of the dust torus. Additionally, the reverberation-based mass is in good agreement with estimates from the scaling relationship of the break in the X-ray power spectral density, and with constraints based on stellar kinematics derived from integral field spectroscopy of the inner ∼0.5 kpc of the galaxy.

  8. A REVERBERATION-BASED BLACK HOLE MASS FOR MCG-06-30-15

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Misty C.; Crenshaw, D. Michael; Ou-Yang, Benjamin [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Cackett, Edward M. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock St., Detroit, MI 48201 (United States); Horne, Keith [SUPA Physics and Astronomy, University of St. Andrews, Fife KY16 9SS (United Kingdom); Street, Rachel, E-mail: bentz@astro.gsu.edu [Las Cumbres Observatory Global Telescope Network, 6740B Cortona Drive, Goleta, CA 93117 (United States)

    2016-10-20

    We present the results of a reverberation campaign targeting MGC-06-30-15. Spectrophotometric monitoring and broad-band photometric monitoring over the course of four months in spring 2012 allowed a determination of a time delay in the broad H β emission line of τ = 5.3 ± 1.8 days in the rest frame of the active galactic nucleus (AGN). Combined with the width of the variable portion of the emission line, we determine a black hole mass of M {sub BH} = (1.6 ± 0.4) × 10{sup 6} M {sub ⊙}. Both the H β time delay and the black hole mass are in good agreement with expectations from the R {sub BLR}– L and M {sub BH}– σ {sub ⋆} relationships for other reverberation-mapped AGNs. The H β time delay is also in good agreement with the relationship between H β and broad-band near-IR delays, in which the effective size of the broad-line region is ∼4–5 times smaller than the inner edge of the dust torus. Additionally, the reverberation-based mass is in good agreement with estimates from the scaling relationship of the break in the X-ray power spectral density, and with constraints based on stellar kinematics derived from integral field spectroscopy of the inner ∼0.5 kpc of the galaxy.

  9. NASA Space Sounds API

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has released a series of space sounds via sound cloud. We have abstracted away some of the hassle in accessing these sounds, so that developers can play with...

  10. One pot synthesis of nanosized anion doped TiO{sub 2}: Effect of irradiation of sound waves on surface morphology and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Sharotri, Nidhi, E-mail: nidhisliet11@gmail.com; Sud, Dhiraj, E-mail: author-suddhiraj@yahoo.com [Department of Chemistry, Sant Longowal Institute of Engineering and Technology, (Deemed University), Longowal 148106, Sangrur, Punjab (India)

    2015-08-28

    Commercialization of AOP’s for remediation of pollutants from environmental matrix required the process to be operated by solar light. Semiconductor TiO{sub 2} has emerged as an effective and preferred photocatalyst in the field of environmental photocatalysis due to its; (i) biological and chemical inertness (ii) resistance to chemical and photo corrosion, (iii) can absorb natural UV light due to appropriate energetic separation between its valence and conduction band. However, unfortunately the optical band gap of TiO{sub 2} (3.0-3.23 eV) with absorption cut off ∼ 380 nm, enables it to harness only a small fraction (∼ 5%) of the entire solar spectrum. One of the current areas of research is modification of TiO{sub 2} photocatalyst. In present paper one pot greener synthesis from titanium isopropoxide and hydroxylamine hydrochloride has been used as titanium and nitrogen precursor under ultrasonic waves. The as synthesized TiO{sub 2} nanomaterials were dried at 100°C and further calcinated at different temperatures. The effect of reaction parameters such as ultrasonication time on the yield, surface morphology, spectroscopic data and optical properties was also investigated. The results confirm that the anatase phase is a main phase with a crystallite size of 35-77 nm and the calculated band gap of nanomaterials varies from 2.10-3.1 eV.

  11. Structure-borne sound structural vibrations and sound radiation at audio frequencies

    CERN Document Server

    Cremer, L; Petersson, Björn AT

    2005-01-01

    Structure-Borne Sound"" is a thorough introduction to structural vibrations with emphasis on audio frequencies and the associated radiation of sound. The book presents in-depth discussions of fundamental principles and basic problems, in order to enable the reader to understand and solve his own problems. It includes chapters dealing with measurement and generation of vibrations and sound, various types of structural wave motion, structural damping and its effects, impedances and vibration responses of the important types of structures, as well as with attenuation of vibrations, and sound radi

  12. Sound Scattering by a Flexible Plate Embedded on Free Surface

    Directory of Open Access Journals (Sweden)

    Eldad J. Avital

    2012-01-01

    Full Text Available Sound wave scattering by a flexible plate embedded on water surface is considered. Linear acoustics and plate elasticity are assumed. The aim is to assess the effect of the plate’s flexibility on sound scattering and the potential in using that flexibility for this purpose. A combined sound-structure solution is used, which is based on a Fourier transform of the sound field and a finite-difference numerical-solution of the plate’s dynamics. The solution is implemented for a circular plate subject to a perpendicular incoming monochromatic sound wave. A very good agreement is achieved with a finite-difference solution of the sound field. It is shown that the flexibility of the plate dampens its scattered sound wave regardless of the type of the plate’s edge support. A hole in the plate is shown to further scatter the sound wave to form maxima in the near sound field. It is suggested that applying an external oscillatory pressure on the plate can reduce significantly and even eliminate its scattered wave, thus making the plate close to acoustically invisible. A uniformly distributed external pressure is found capable of achieving that aim as long as the plate is free edged or is not highly acoustically noncompact.

  13. Cracking investigation of Monju emergency generator C unit cylinder liner. Cylinder liner soundness confirmation by a fall cause of the materials strength of the cylinder liner and the supersonic wave speed

    International Nuclear Information System (INIS)

    Kobayashi, Takanori; Sakon, Miyoji; Takada, Osamu; Hatori, Masakazu; Sakamoto, Tsutomu; Sato, Toshiyuki; Kazama, Akihito; Ishizawa, Yoshihiro; Igawa, Katsuhisa; Nakae, Hideo

    2012-02-01

    I confirmed a leak of the effluent gas from cylinder part during a load examination after the check of the emergency generator C unit on December 28, 2010 of the facilities check average and confirmed crack in No.8 cylinder liner part. As a result, because it was not performed oil pressure management properly without attaching an oil pressure gauge when I removed cylinder liner about the cause, crack occurred by having been able to write excessive stress for the cylinder liner and reached damage. By a process of this investigation, a fall of the materials strength of some cylinder liner was confirmed, but because a lead ingredient got mixed with materials by a casting process at the time of the production of the cylinder liner, as for this, Widmannstaetten graphite occurred, and it became clear that materials strength fell. In addition, I performed inspection by the supersonic wave velocity measurement as technique to distinguish this Widmannstaetten graphite easily and confirmed that I was effective. Because this report was the knowledge that there were little inspection contents which modified soundness confirmation technique of the cylinder liner with the possibility of materials strength fall of the cylinder liner by the Widmannstaetten graphite outbreak and the mixture of lead for a report example in the field of cast iron, I gathered it in this report. (author)

  14. Infra-sound cancellation and mitigation in wind turbines

    Science.gov (United States)

    Boretti, Albert; Ordys, Andrew; Al Zubaidy, Sarim

    2018-03-01

    The infra-sound spectra recorded inside homes located even several kilometres far from wind turbine installations is characterized by large pressure fluctuation in the low frequency range. There is a significant body of literature suggesting inaudible sounds at low frequency are sensed by humans and affect the wellbeing through different mechanisms. These mechanisms include amplitude modulation of heard sounds, stimulating subconscious pathways, causing endolymphatic hydrops, and possibly potentiating noise-induced hearing loss. We suggest the study of infra-sound active cancellation and mitigation to address the low frequency noise issues. Loudspeakers generate pressure wave components of same amplitude and frequency but opposite phase of the recorded infra sound. They also produce pressure wave components within the audible range reducing the perception of the infra-sound to minimize the sensing of the residual infra sound.

  15. Sounds Exaggerate Visual Shape

    Science.gov (United States)

    Sweeny, Timothy D.; Guzman-Martinez, Emmanuel; Ortega, Laura; Grabowecky, Marcia; Suzuki, Satoru

    2012-01-01

    While perceiving speech, people see mouth shapes that are systematically associated with sounds. In particular, a vertically stretched mouth produces a /woo/ sound, whereas a horizontally stretched mouth produces a /wee/ sound. We demonstrate that hearing these speech sounds alters how we see aspect ratio, a basic visual feature that contributes…

  16. Neuromorphic Audio-Visual Sensor Fusion on a Sound-Localising Robot

    Directory of Open Access Journals (Sweden)

    Vincent Yue-Sek Chan

    2012-02-01

    Full Text Available This paper presents the first robotic system featuring audio-visual sensor fusion with neuromorphic sensors. We combine a pair of silicon cochleae and a silicon retina on a robotic platform to allow the robot to learn sound localisation through self-motion and visual feedback, using an adaptive ITD-based sound localisation algorithm. After training, the robot can localise sound sources (white or pink noise in a reverberant environment with an RMS error of 4 to 5 degrees in azimuth. In the second part of the paper, we investigate the source binding problem. An experiment is conducted to test the effectiveness of matching an audio event with a corresponding visual event based on their onset time. The results show that this technique can be quite effective, despite its simplicity.

  17. Effects of Interaural Level and Time Differences on the Externalization of Sound

    DEFF Research Database (Denmark)

    Dau, Torsten; Catic, Jasmina; Santurette, Sébastien

    Distant sound sources in our environment are perceived as externalized and are thus properly localized in both direction and distance. This is due to the acoustic filtering by the head, torso, and external ears, which provides frequency dependent shaping of binaural cues, such as interaural level...... differences (ILDs) and interaural time differences (ITDs). Further, the binaural cues provided by reverberation in an enclosed space may also contribute to externalization. While these spatial cues are available in their natural form when listening to real-world sound sources, hearing-aid signal processing...... is consistent with the physical analysis that showed that a decreased distance to the sound source also reduced the fluctuations in ILDs....

  18. NIS method for uncertainty estimation of airborne sound insulation measurement in field

    Directory of Open Access Journals (Sweden)

    El-Basheer Tarek M.

    2017-01-01

    Full Text Available In structures, airborne sound insulation is utilized to characterize the acoustic nature of barriers between rooms. However, the assessment of sound insulation index is once in a while troublesome or indeed, even questionable, both in field and laboratory measurements, notwithstanding the way that there are some unified measurement methodology indicated in the ISO 140 series standards. There are issues with the reproducibility and repeatability of the measurement results. A few troubles might be brought on by non-diffuse acoustic fields, non-uniform reverberation time, or blunders of the reverberation time measurements. Some minor issues are additionally postured by flanking transmission. In this paper, investigation of the uncertainties of the above specified measurement parts and their impact on the consolidated uncertainty in 1/3-octave frequency band. The total measurement uncertainty model contributes several different partial uncertainties, which are evaluated by the method of type A or type B. Also, the determination of the sound reduction index decided by ISO 140-4 has been performed.

  19. Little Sounds

    Directory of Open Access Journals (Sweden)

    Baker M. Bani-Khair

    2017-10-01

    Full Text Available The Spider and the Fly   You little spider, To death you aspire... Or seeking a web wider, To death all walking, No escape you all fighters… Weak and fragile in shape and might, Whatever you see in the horizon, That is destiny whatever sight. And tomorrow the spring comes, And the flowers bloom, And the grasshopper leaps high, And the frogs happily cry, And the flies smile nearby, To that end, The spider has a plot, To catch the flies by his net, A mosquito has fallen down in his net, Begging him to set her free, Out of that prison, To her freedom she aspires, Begging...Imploring...crying,  That is all what she requires, But the spider vows never let her free, His power he admires, Turning blind to light, And with his teeth he shall bite, Leaving her in desperate might, Unable to move from site to site, Tied up with strings in white, Wrapped up like a dead man, Waiting for his grave at night,   The mosquito says, Oh little spider, A stronger you are than me in power, But listen to my words before death hour, Today is mine and tomorrow is yours, No escape from death... Whatever the color of your flower…     Little sounds The Ant The ant is a little creature with a ferocious soul, Looking and looking for more and more, You can simply crush it like dead mold, Or you can simply leave it alone, I wonder how strong and strong they are! Working day and night in a small hole, Their motto is work or whatever you call… A big boon they have and joy in fall, Because they found what they store, A lesson to learn and memorize all in all, Work is something that you should not ignore!   The butterfly: I’m the butterfly Beautiful like a blue clear sky, Or sometimes look like snow, Different in colors, shapes and might, But something to know that we always die, So fragile, weak and thin, Lighter than a glimpse and delicate as light, Something to know for sure… Whatever you have in life and all these fields, You are not happier than a butterfly

  20. First- and Second-level Bayesian Inference of Flow Resistivity of Sound Absorber and Room’s Influence

    DEFF Research Database (Denmark)

    Choi, Sang-Hyeon; Lee, Ikjin; Jeong, Cheol-Ho

    2016-01-01

    Sabine absorption coefficient is a widely used one deduced from reverberation time measurements via the Sabine equation. First- and second-level Bayesian analysis are used to estimate the flow resistivity of a sound absorber and the influences of the test chambers from Sabine absorption...... coefficients measured in 13 different reverberation chambers. The first-level Bayesian analysis is more general than the second-level Bayesian analysis. Sharper posterior distribution can be acquired by the second-level Bayesian analysis than the one by the first-level Bayesian analysis because more data...... are used to set more reliable prior distribution. The estimated room’s influences by the first- and the second-level Bayesian analyses are similar to the estimated results by the mean absolute error minimization....

  1. Towards Predicting Room Acoustical Effects on Sound-Field ASSR from Stimulus Modulation Power

    DEFF Research Database (Denmark)

    Zapata Rodriguez, Valentina; Laugesen, Søren; Jeong, Cheol-Ho

    ) is considered. Instead of using insert earphones to deliver the stimuli, as is customary, the auditory signals are reproduced from a loudspeaker placed in front of the subject, so as to include the hearing aid in the transmission path. Loudspeaker presentation of the stimulus can lower its effective modulation...... properties of the measurement room has not been considered. The present work explores the relation between the stimulus modulation power and the ASSR amplitude in a simulated sound-field ASSR data set with varying reverberation time. Three rooms were simulated using the Green's function approach...

  2. Sound: Conceivably the creative language of God, holding all of creation in concert

    Directory of Open Access Journals (Sweden)

    Mark Pretorius

    2011-03-01

    Full Text Available This paper revolved around the idea that sound within light is the primary medium God used to bring all of creation into existence (creatio. The theory is that the harmonic tones embedded within the initial spoken light of Genesis 1:3 are still reverberating within creation today (concursus and can be used for the benefit of all (providentia. This simply means thatnature is providentially geared to move in a specific direction, according to God�s overall plan for everyone�s benefit.

  3. Comment on ''On the upconversion of ion sound to Langmuir turbulence,'' By L. Vlahos and K. Papadopoulos

    International Nuclear Information System (INIS)

    Kuijpers, J.

    1980-01-01

    It is shown that the production of Langmuir waves from ion sound by the turbulent Bremsstrahlung mechanism can be more effective than the destruction of the Langmuir waves by the Dawson-Oberman resistivity. Previous conclusions to the contrary are in error owing to the neglect of the wave-number dependence of the ion-sound waves

  4. Second sound scattering in superfluid helium

    International Nuclear Information System (INIS)

    Rosgen, T.

    1985-01-01

    Focusing cavities are used to study the scattering of second sound in liquid helium II. The special geometries reduce wall interference effects and allow measurements in very small test volumes. In a first experiment, a double elliptical cavity is used to focus a second sound wave onto a small wire target. A thin film bolometer measures the side scattered wave component. The agreement with a theoretical estimate is reasonable, although some problems arise from the small measurement volume and associated alignment requirements. A second cavity is based on confocal parabolas, thus enabling the use of large planar sensors. A cylindrical heater produces again a focused second sound wave. Three sensors monitor the transmitted wave component as well as the side scatter in two different directions. The side looking sensors have very high sensitivities due to their large size and resistance. Specially developed cryogenic amplifers are used to match them to the signal cables. In one case, a second auxiliary heater is used to set up a strong counterflow in the focal region. The second sound wave then scatters from the induced fluid disturbances

  5. The Sloan Digital Sky Survey Reverberation Mapping Project: Composite Lags at z ≤ 1

    Science.gov (United States)

    Li, Jennifer; Shen, Yue; Horne, Keith; Brandt, W. N.; Greene, Jenny E.; Grier, C. J.; Ho, Luis C.; Kochanek, Chris; Schneider, Donald P.; Trump, Jonathan R.; Dawson, Kyle S.; Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena

    2017-09-01

    We present composite broad-line region (BLR) reverberation mapping lag measurements for Hα, Hβ, He II λ4686, and Mg II for a sample of 144, z ≲ 1 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Using only the 32-epoch spectroscopic light curves in the first six-month season of SDSS-RM observations, we compile correlation function measurements for individual objects and then coadd them to allow the measurement of the average lags for our sample at mean redshifts of 0.4 (for Hα) and ˜0.65 (for the other lines). At similar quasar luminosities and redshifts, the sample-averaged lag decreases in the order of Mg II, Hα, Hβ, and He II. This decrease in lags is accompanied by an increase in the mean line width of the four lines, and is roughly consistent with the virialized motion for BLR gas in photoionization equilibrium. These are among the first RM measurements of stratified BLR structure at z > 0.3. Dividing our sample by luminosity, Hα shows clear evidence of increasing lags with luminosity, consistent with the expectation from the measured BLR size-luminosity relation based on Hβ. The other three lines do not show a clear luminosity trend in their average lags due to the limited dynamic range of luminosity probed and the poor average correlation signals in the divided samples, a situation that will be improved with the incorporation of additional photometric and spectroscopic data from SDSS-RM. We discuss the utility and caveats of composite lag measurements for large statistical quasar samples with reverberation mapping data.

  6. The Sloan Digital Sky Survey Reverberation Mapping Project: Composite Lags at z ≤ 1

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jennifer; Shen, Yue [Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Horne, Keith [SUPA Physics/Astronomy, Univ. of St. Andrews, St. Andrews KY16 9SS (United Kingdom); Brandt, W. N.; Grier, C. J.; Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA, 16802 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Kochanek, Chris [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Trump, Jonathan R. [Department of Physics, University of Connecticut, 2152 Hillside Road, Unit 3046, Storrs, CT 06269 (United States); Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States)

    2017-09-01

    We present composite broad-line region (BLR) reverberation mapping lag measurements for H α , H β , He ii λ 4686, and Mg ii for a sample of 144, z ≲ 1 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Using only the 32-epoch spectroscopic light curves in the first six-month season of SDSS-RM observations, we compile correlation function measurements for individual objects and then coadd them to allow the measurement of the average lags for our sample at mean redshifts of 0.4 (for H α ) and ∼0.65 (for the other lines). At similar quasar luminosities and redshifts, the sample-averaged lag decreases in the order of Mg ii, H α , H β , and He ii. This decrease in lags is accompanied by an increase in the mean line width of the four lines, and is roughly consistent with the virialized motion for BLR gas in photoionization equilibrium. These are among the first RM measurements of stratified BLR structure at z > 0.3. Dividing our sample by luminosity, H α shows clear evidence of increasing lags with luminosity, consistent with the expectation from the measured BLR size–luminosity relation based on H β . The other three lines do not show a clear luminosity trend in their average lags due to the limited dynamic range of luminosity probed and the poor average correlation signals in the divided samples, a situation that will be improved with the incorporation of additional photometric and spectroscopic data from SDSS-RM. We discuss the utility and caveats of composite lag measurements for large statistical quasar samples with reverberation mapping data.

  7. SOFT LAGS IN NEUTRON STAR kHz QUASI-PERIODIC OSCILLATIONS: EVIDENCE FOR REVERBERATION?

    Energy Technology Data Exchange (ETDEWEB)

    Barret, Didier, E-mail: didier.barret@irap.omp.eu [Universite de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); CNRS, Institut de Recherche en Astrophysique et Planetologie, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

    2013-06-10

    High frequency soft reverberation lags have now been detected from stellar mass and supermassive black holes. Their interpretation involves reflection of a hard source of photons onto an accretion disk, producing a delayed reflected emission, with a time lag consistent with the light travel time between the irradiating source and the disk. Independently of the location of the clock, the kHz quasi-periodic oscillation (QPO) emission is thought to arise from the neutron star boundary layer. Here, we search for the signature of reverberation of the kHz QPO emission, by measuring the soft lags and the lag energy spectrum of the lower kHz QPOs from 4U1608-522. Soft lags, ranging from {approx}15 to {approx}40 {mu}s, between the 3-8 keV and 8-30 keV modulated emissions are detected between 565 and 890 Hz. The soft lags are not constant with frequency and show a smooth decrease between 680 Hz and 890 Hz. The broad band X-ray spectrum is modeled as the sum of a disk and a thermal Comptonized component, plus a broad iron line, expected from reflection. The spectral parameters follow a smooth relationship with the QPO frequency, in particular the fitted inner disk radius decreases steadily with frequency. Both the bump around the iron line in the lag energy spectrum and the consistency between the lag changes and the inferred changes of the inner disk radius, from either spectral fitting or the QPO frequency, suggest that the soft lags may indeed involve reverberation of the hard pulsating QPO source on the disk.

  8. BROAD-LINE REVERBERATION IN THE KEPLER-FIELD SEYFERT GALAXY Zw 229-015

    International Nuclear Information System (INIS)

    Barth, Aaron J.; Nguyen, My L.; Malkan, Matthew A.; Filippenko, Alexei V.; Li, Weidong; Cenko, S. Bradley; Choi, Jieun; Duchene, Gaspard; Ganeshalingam, Mohan; Gorjian, Varoujan; Joner, Michael D.; Bennert, Vardha Nicola; Botyanszki, Janos; Childress, Michael; Cucciara, Antonino; Comerford, Julia M.; Da Silva, Robert; Fumagalli, Michele; Gates, Elinor L.; Gerke, Brian F.

    2011-01-01

    The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from Hβ reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad Hβ flux. From cross-correlation measurements, we find that the Hβ light curve has a rest-frame lag of 3.86 +0.69 -0.90 days with respect to the V-band continuum variations. We also measure reverberation lags for Hα and Hγ and find an upper limit to the Hδ lag. Combining the Hβ lag measurement with a broad Hβ width of σ line = 1590 ± 47 km s -1 measured from the rms variability spectrum, we obtain a virial estimate of M BH = 1.00 +0.19 -0.24 x 10 7 M sun for the black hole in Zw 229-015. As a Kepler target, Zw 229-015 will eventually have one of the highest-quality optical light curves ever measured for any active galaxy, and the black hole mass determined from reverberation mapping will serve as a benchmark for testing relationships between black hole mass and continuum variability characteristics in active galactic nuclei.

  9. The Sloan Digital Sky Survey Reverberation Mapping Project: Composite Lags at z ≤ 1

    International Nuclear Information System (INIS)

    Li, Jennifer; Shen, Yue; Horne, Keith; Brandt, W. N.; Grier, C. J.; Schneider, Donald P.; Greene, Jenny E.; Ho, Luis C.; Kochanek, Chris; Trump, Jonathan R.; Dawson, Kyle S.; Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena

    2017-01-01

    We present composite broad-line region (BLR) reverberation mapping lag measurements for H α , H β , He ii λ 4686, and Mg ii for a sample of 144, z ≲ 1 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Using only the 32-epoch spectroscopic light curves in the first six-month season of SDSS-RM observations, we compile correlation function measurements for individual objects and then coadd them to allow the measurement of the average lags for our sample at mean redshifts of 0.4 (for H α ) and ∼0.65 (for the other lines). At similar quasar luminosities and redshifts, the sample-averaged lag decreases in the order of Mg ii, H α , H β , and He ii. This decrease in lags is accompanied by an increase in the mean line width of the four lines, and is roughly consistent with the virialized motion for BLR gas in photoionization equilibrium. These are among the first RM measurements of stratified BLR structure at z > 0.3. Dividing our sample by luminosity, H α shows clear evidence of increasing lags with luminosity, consistent with the expectation from the measured BLR size–luminosity relation based on H β . The other three lines do not show a clear luminosity trend in their average lags due to the limited dynamic range of luminosity probed and the poor average correlation signals in the divided samples, a situation that will be improved with the incorporation of additional photometric and spectroscopic data from SDSS-RM. We discuss the utility and caveats of composite lag measurements for large statistical quasar samples with reverberation mapping data.

  10. The Influence of Visual Cues on Sound Externalization

    DEFF Research Database (Denmark)

    Carvajal, Juan Camilo Gil; Santurette, Sébastien; Cubick, Jens

    while listeners wore both earplugs and blindfolds. Half of the listeners were then blindfolded during testing but were provided auditory awareness of the room via a controlled noise source (condition A). The other half could see the room but were shielded from room-related acoustic input and tested......Background: The externalization of virtual sounds reproduced via binaural headphone-based auralization systems has been reported to be less robust when the listening environment differs from the room in which binaural room impulse responses (BRIRs) were recorded. It has been debated whether.......Methods: Eighteen naïve listeners rated the externalization of virtual stimuli in terms of perceived distance, azimuthal localization, and compactness in three rooms: 1) a standard IEC listening room, 2) a small reverberant room, and 3) a large dry room. Before testing, individual BRIRs were recorded in room 1...

  11. Timbral aspects of reproduced sound in small rooms. II

    DEFF Research Database (Denmark)

    Bech, Søren

    1996-01-01

    A single loudspeaker with frequency-dependent directivity characteristics, positioned in a room of normal size with frequency-dependent absorption coefficients of the room surfaces, has been simulated using an electroacoustic setup. The model included the direct sound, seventeen individual...... reflections and the reverberant field. The threshold of detection, and just-noticeable differences for an increase in level were measured for individual reflections. The results have confirmed that the first-order floor reflection is likely to contribute individually to the timbre of reproduced noise. However......, for a speech signal none of the investigated reflections will contribute individually to the timbre. It is suggested that the threshold of detection is determined by the spectral changes in the dominant frequency range of 500 Hz to 2 kHz. For increases in the level of individual reflections, the most likely...

  12. Multichannel active control of random noise in a small reverberant room

    DEFF Research Database (Denmark)

    Laugesen, Søren; Elliott, Stephen J.

    1993-01-01

    An algorithm for multichannel adaptive IIR (infinite impulse response) filtering is presented and applied to the active control of broadband random noise in a small reverberant room. Assuming complete knowledge of the primary noise, the theoretically optimal reductions of acoustic energy are init...... with the primary noise field generated by a panel excited by a loudspeaker in an adjoining room. These results show that far better performances are provided by IIR and FIR filters when the primary source has a lightly damped dynamic behavior which the active controller must model...

  13. Efficient voice activity detection in reverberant enclosures using far field microphones

    DEFF Research Database (Denmark)

    Petsatodis, Theodore; Boukis, Christos

    2009-01-01

    An algorithm suitable for voice activity detection under reverberant conditions is proposed in this paper. Due to the use of far-filed microphones the proposed solution processes speech signals of highly-varying intensity and signal to noise ratio, that are contaminated with several echoes....... The core of the system is a pair of Hidden Markov Models, that effectively model the speech presence and speech absence situations. To minimise mis-detections an adaptive threshold is used, while a hang-over scheme caters for the intra-frame correlation of speech signals. Experimental results conducted...

  14. Usage of measured reverberation tail in a binaural room impulse response synthesis

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Madsen, Esben

    2011-01-01

    The aim of the modern communication technologies is an immersive experience. One of the applications that should provide the feeling of being together and sharing the same environment during the communication process is BEAMING. The goal of this paper is to improve audible spatial impression...... utilizing correct acoustical properties of the specific environments. Binaural room impulse response (BRIR) synthesis represents one of the main tasks in the binaural auralization. When the BRIRs are simulated, high order reflections (reverberation tail) are usually modeled statistically because of the high...

  15. Directional sound radiation from substation transformers

    International Nuclear Information System (INIS)

    Maybee, N.

    2009-01-01

    This paper presented the results of a study in which acoustical measurements at two substations were analyzed to investigate the directional behaviour of typical arrays having 2 or 3 transformers. Substation transformers produce a characteristic humming sound that is caused primarily by vibration of the core at twice the frequency of the power supply. The humming noise radiates predominantly from the tank enclosing the core. The main components of the sound are harmonics of 120 Hz. Sound pressure level data were obtained for various directions and distances from the arrays, ranging from 0.5 m to over 100 m. The measured sound pressure levels of the transformer tones displayed substantial positive and negative excursions from the calculated average values for many distances and directions. The results support the concept that the directional effects are associated with constructive and destructive interference of tonal sound waves emanating from different parts of the array. Significant variations in the directional sound pattern can occur in the near field of a single transformer or an array, and the extent of the near field is significantly larger than the scale of the array. Based on typical dimensions for substation sites, the distance to the far field may be much beyond the substation boundary and beyond typical setbacks to the closest dwellings. As such, the directional sound radiation produced by transformer arrays introduces additional uncertainty in the prediction of substation sound levels at dwellings within a few hundred meters of a substation site. 4 refs., 4 figs.

  16. Numerical Analysis of Indoor Sound Quality Evaluation Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Yu-Tuan Chou

    2013-01-01

    Full Text Available Indoors sound field distribution is important to Room Acoustics, but the field suffers numerous problems, for example, multipath propagation and scattering owing to sound absorption by furniture and other aspects of décor. Generally, an ideal interior space must have a sound field with clear quality. This provides both the speaker and the listener with a pleasant conversational environment. This investigation uses the Finite Element Method to assess the acoustic distribution based on the indoor space and chamber volume. In this situation, a fixed sound source at different frequencies is used to simulate the acoustic characteristics of the indoor space. This method considers the furniture and decoration sound absorbing material and thus different sound absorption coefficients and configurations. The preliminary numerical simulation provides a method that can forecast the distribution of sound in an indoor room in complex situations. Consequently, it is possible to arrange interior furnishings and appliances to optimize acoustic distribution and environmental friendliness. Additionally, the analytical results can also be used to calculate the Reverberation Time and speech intelligibility for specified indoor space.

  17. Sparse representation of Gravitational Sound

    Science.gov (United States)

    Rebollo-Neira, Laura; Plastino, A.

    2018-03-01

    Gravitational Sound clips produced by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Massachusetts Institute of Technology (MIT) are considered within the particular context of data reduction. We advance a procedure to this effect and show that these types of signals can be approximated with high quality using significantly fewer elementary components than those required within the standard orthogonal basis framework. Furthermore, a local measure sparsity is shown to render meaningful information about the variation of a signal along time, by generating a set of local sparsity values which is much smaller than the dimension of the signal. This point is further illustrated by recourse to a more complex signal, generated by Milde Science Communication to divulge Gravitational Sound in the form of a ring tone.

  18. Measuring the speed of sound in air using smartphone applications

    Science.gov (United States)

    Yavuz, A.

    2015-05-01

    This study presents a revised version of an old experiment available in many textbooks for measuring the speed of sound in air. A signal-generator application in a smartphone is used to produce the desired sound frequency. Nodes of sound waves in a glass pipe, of which one end is immersed in water, are more easily detected, so results can be obtained more quickly than from traditional acoustic experiments using tuning forks.

  19. Quasar Accretion Disk Sizes With Continuum Reverberation Mapping From the Dark Energy Survey

    Energy Technology Data Exchange (ETDEWEB)

    Mudd, D.; et al.

    2017-11-30

    We present accretion disk size measurements for 15 luminous quasars at $0.7 \\leq z \\leq 1.9$ derived from $griz$ light curves from the Dark Energy Survey. We measure the disk sizes with continuum reverberation mapping using two methods, both of which are derived from the expectation that accretion disks have a radial temperature gradient and the continuum emission at a given radius is well-described by a single blackbody. In the first method we measure the relative lags between the multiband light curves, which provides the relative time lag between shorter and longer wavelength variations. The second method fits the model parameters for the canonical Shakura-Sunyaev thin disk directly rather than solving for the individual time lags between the light curves. Our measurements demonstrate good agreement with the sizes predicted by this model for accretion rates between 0.3-1 times the Eddington rate. These results are also in reasonable agreement with disk size measurements from gravitational microlensing studies of strongly lensed quasars, as well as other photometric reverberation mapping results.

  20. Methods of Reverberation Mapping. I. Time-lag Determination by Measures of Randomness

    Energy Technology Data Exchange (ETDEWEB)

    Chelouche, Doron; Pozo-Nuñez, Francisco [Department of Physics, Faculty of Natural Sciences, University of Haifa, Haifa 3498838 (Israel); Zucker, Shay, E-mail: doron@sci.haifa.ac.il, E-mail: francisco.pozon@gmail.com, E-mail: shayz@post.tau.ac.il [Department of Geosciences, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801 (Israel)

    2017-08-01

    A class of methods for measuring time delays between astronomical time series is introduced in the context of quasar reverberation mapping, which is based on measures of randomness or complexity of the data. Several distinct statistical estimators are considered that do not rely on polynomial interpolations of the light curves nor on their stochastic modeling, and do not require binning in correlation space. Methods based on von Neumann’s mean-square successive-difference estimator are found to be superior to those using other estimators. An optimized von Neumann scheme is formulated, which better handles sparsely sampled data and outperforms current implementations of discrete correlation function methods. This scheme is applied to existing reverberation data of varying quality, and consistency with previously reported time delays is found. In particular, the size–luminosity relation of the broad-line region in quasars is recovered with a scatter comparable to that obtained by other works, yet with fewer assumptions made concerning the process underlying the variability. The proposed method for time-lag determination is particularly relevant for irregularly sampled time series, and in cases where the process underlying the variability cannot be adequately modeled.

  1. Broadband Photometric Reverberation Mapping Analysis on SDSS-RM and Stripe 82 Quasars

    Science.gov (United States)

    Zhang, Haowen; Yang, Qian; Wu, Xue-Bing

    2018-02-01

    We modified the broadband photometric reverberation mapping (PRM) code, JAVELIN, and tested the availability to get broad-line region time delays that are consistent with the spectroscopic reverberation mapping (SRM) project SDSS-RM. The broadband light curves of SDSS-RM quasars produced by convolution with the system transmission curves were used in the test. We found that under similar sampling conditions (evenly and frequently sampled), the key factor determining whether the broadband PRM code can yield lags consistent with the SRM project is the flux ratio of the broad emission line to the reference continuum, which is in line with the previous findings. We further found a critical line-to-continuum flux ratio, about 6%, above which the mean of the ratios between the lags from PRM and SRM becomes closer to unity, and the scatter is pronouncedly reduced. We also tested our code on a subset of SDSS Stripe 82 quasars, and found that our program tends to give biased lag estimations due to the observation gaps when the R-L relation prior in Markov Chain Monte Carlo is discarded. The performance of the damped random walk (DRW) model and the power-law (PL) structure function model on broadband PRM were compared. We found that given both SDSS-RM-like or Stripe 82-like light curves, the DRW model performs better in carrying out broadband PRM than the PL model.

  2. Making fictions sound real

    DEFF Research Database (Denmark)

    Langkjær, Birger

    2010-01-01

    This article examines the role that sound plays in making fictions perceptually real to film audiences, whether these fictions are realist or non-realist in content and narrative form. I will argue that some aspects of film sound practices and the kind of experiences they trigger are related...... to basic rules of human perception, whereas others are more properly explained in relation to how aesthetic devices, including sound, are used to characterise the fiction and thereby make it perceptually real to its audience. Finally, I will argue that not all genres can be defined by a simple taxonomy...... of sounds. Apart from an account of the kinds of sounds that typically appear in a specific genre, a genre analysis of sound may also benefit from a functionalist approach that focuses on how sounds can make both realist and non-realist aspects of genres sound real to audiences....

  3. Principles of underwater sound

    National Research Council Canada - National Science Library

    Urick, Robert J

    1983-01-01

    ... the immediately useful help they need for sonar problem solving. Its coverage is broad-ranging from the basic concepts of sound in the sea to making performance predictions in such applications as depth sounding, fish finding, and submarine detection...

  4. Speed of sound in the solar interior

    International Nuclear Information System (INIS)

    Christensen-Dalsgaard, J.; Rhodes, E.J. Jr.

    1985-01-01

    Frequencies of solar 5-min oscillations can be used to determine directly the sound speed of the solar interior. The determination described does not depend on a solar model, but relies only on a simple asymptotic description of the oscillations in terms of trapped acoustic waves. (author)

  5. Topology optimized cloak for airborne sound

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders; Sigmund, Ole

    2013-01-01

    Directional acoustic cloaks that conceal an aluminum cylinder for airborne sound waves are presented in this paper. Subwavelength cylindrical aluminum inclusions in air constitute the cloak design to aid practical realizations. The positions and radii of the subwavelength cylinders are determined...

  6. An Antropologist of Sound

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh

    2015-01-01

    PROFESSOR PORTRAIT: Sanne Krogh Groth met Holger Schulze, newly appointed professor in Musicology at the Department for Arts and Cultural Studies, University of Copenhagen, to a talk about anthropology of sound, sound studies, musical canons and ideology.......PROFESSOR PORTRAIT: Sanne Krogh Groth met Holger Schulze, newly appointed professor in Musicology at the Department for Arts and Cultural Studies, University of Copenhagen, to a talk about anthropology of sound, sound studies, musical canons and ideology....

  7. Propagation of sound

    DEFF Research Database (Denmark)

    Wahlberg, Magnus; Larsen, Ole Næsbye

    2017-01-01

    properties can be modified by sound absorption, refraction, and interference from multi paths caused by reflections.The path from the source to the receiver may be bent due to refraction. Besides geometrical attenuation, the ground effect and turbulence are the most important mechanisms to influence...... communication sounds for airborne acoustics and bottom and surface effects for underwater sounds. Refraction becomes very important close to shadow zones. For echolocation signals, geometric attenuation and sound absorption have the largest effects on the signals....

  8. The screening of sound in a subsonic flow by a cylindrical airbubble layer and a semi-infinite tube

    NARCIS (Netherlands)

    Grand, Pieter le

    1971-01-01

    The problem here under discussion lies in the field of sound waves in layered media. The presence of a layer with a velocity of sound less than that of the surroundings will enable sound waves to travel along great distances. In this domain many investigations have been made e. g. in connection with

  9. Abnormal sound detection device

    International Nuclear Information System (INIS)

    Yamada, Izumi; Matsui, Yuji.

    1995-01-01

    Only components synchronized with rotation of pumps are sampled from detected acoustic sounds, to judge the presence or absence of abnormality based on the magnitude of the synchronized components. A synchronized component sampling means can remove resonance sounds and other acoustic sounds generated at a synchronously with the rotation based on the knowledge that generated acoustic components in a normal state are a sort of resonance sounds and are not precisely synchronized with the number of rotation. On the other hand, abnormal sounds of a rotating body are often caused by compulsory force accompanying the rotation as a generation source, and the abnormal sounds can be detected by extracting only the rotation-synchronized components. Since components of normal acoustic sounds generated at present are discriminated from the detected sounds, reduction of the abnormal sounds due to a signal processing can be avoided and, as a result, abnormal sound detection sensitivity can be improved. Further, since it is adapted to discriminate the occurrence of the abnormal sound from the actually detected sounds, the other frequency components which are forecast but not generated actually are not removed, so that it is further effective for the improvement of detection sensitivity. (N.H.)

  10. Modelling Hyperboloid Sound Scattering

    DEFF Research Database (Denmark)

    Burry, Jane; Davis, Daniel; Peters, Brady

    2011-01-01

    The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering....

  11. Dissipation in vibrating superleak second sound transducers

    International Nuclear Information System (INIS)

    Giordano, N.

    1985-01-01

    We have performed an experimental study of the generation and detection of second sound in 4 He using vibrating superleak second sound transducers. At temperatures well below T/sub lambda/ and for low driving amplitudes, the magnitude of the generated second sound wave is proportional to the drive amplitude. However, near T/sub lambda/ and for high drive amplitudes this is no longer the case--instead, the second sound amplitude saturates. In this regime we also find that overtones of the drive frequency are generated. Our results suggest that this behavior is due to critical velocity effects in the pores of the superleak in the generator transducer. This type of measurement may prove to be a useful way in which to study critical velocity effects in confined geometries

  12. Non-Wovens as Sound Reducers

    Science.gov (United States)

    Belakova, D.; Seile, A.; Kukle, S.; Plamus, T.

    2018-04-01

    Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

  13. Misconceptions About Sound Among Engineering Students

    Science.gov (United States)

    Pejuan, Arcadi; Bohigas, Xavier; Jaén, Xavier; Periago, Cristina

    2012-12-01

    Our first objective was to detect misconceptions about the microscopic nature of sound among senior university students enrolled in different engineering programmes (from chemistry to telecommunications). We sought to determine how these misconceptions are expressed (qualitative aspect) and, only very secondarily, to gain a general idea of the extent to which they are held (quantitative aspect). Our second objective was to explore other misconceptions about wave aspects of sound. We have also considered the degree of consistency in the model of sound used by each student. Forty students answered a questionnaire including open-ended questions. Based on their free, spontaneous answers, the main results were as follows: a large majority of students answered most of the questions regarding the microscopic model of sound according to the scientifically accepted model; however, only a small number answered consistently. The main model misconception found was the notion that sound is propagated through the travelling of air particles, even in solids. Misconceptions and mental-model inconsistencies tended to depend on the engineering programme in which the student was enrolled. However, students in general were inconsistent also in applying their model of sound to individual sound properties. The main conclusion is that our students have not truly internalised the scientifically accepted model that they have allegedly learnt. This implies a need to design learning activities that take these findings into account in order to be truly efficient.

  14. Intelligibility and Clarity of Reverberant Speech: Effects of Wide Dynamic Range Compression Release Time and Working Memory

    Science.gov (United States)

    Reinhart, Paul N.; Souza, Pamela E.

    2016-01-01

    Purpose: The purpose of this study was to examine the effects of varying wide dynamic range compression (WDRC) release time on intelligibility and clarity of reverberant speech. The study also considered the role of individual working memory. Method: Thirty older listeners with mild to moderately-severe sloping sensorineural hearing loss…

  15. Reverberation index: a novel metric by which to quantify the impact of a scientific entity on a given field.

    Science.gov (United States)

    Kathleen Bandt, S; Dacey, Ralph G

    2017-09-01

    The authors propose a novel bibilometric index, the reverberation index (r-index), as a comparative assessment tool for use in determining differential reverberation between scientific fields for a given scientific entity. Conversely, this may allow comparison of 2 similar scientific entities within a single scientific field. This index is calculated using a relatively simple 3-step process. Briefly, Thompson Reuters' Web of Science is used to produce a citation report for a unique search parameter (this may be an author, journal article, or topical key word). From this citation report, a list of citing journals is retrieved from which a weighted ratio of citation patterns across journals can be calculated. This r-index is then used to compare the reverberation of the original search parameter across different fields of study or wherever a comparison is required. The advantage of this novel tool is its ability to transcend a specific component of the scientific process. This affords application to a diverse range of entities, including an author, a journal article, or a topical key word, for effective comparison of that entity's reverberation within a scientific arena. The authors introduce the context for and applications of the r-index, emphasizing neurosurgical topics and journals for illustration purposes. It should be kept in mind, however, that the r-index is readily applicable across all fields of study.

  16. Elements of a Sound Education.

    Science.gov (United States)

    Brooks, Christopher

    2003-01-01

    Discusses what do to about the poor acoustics in school multipurpose rooms, asserting that because the auditorium is the most critical function of a typical multipurpose room, the stage house is superficial and noise control is essential. Features to enhance auditorium function include a performance platform and reverberation control. The article…

  17. Floquet topological insulators for sound

    Science.gov (United States)

    Fleury, Romain; Khanikaev, Alexander B.; Alù, Andrea

    2016-06-01

    The unique conduction properties of condensed matter systems with topological order have recently inspired a quest for the similar effects in classical wave phenomena. Acoustic topological insulators, in particular, hold the promise to revolutionize our ability to control sound, allowing for large isolation in the bulk and broadband one-way transport along their edges, with topological immunity against structural defects and disorder. So far, these fascinating properties have been obtained relying on moving media, which may introduce noise and absorption losses, hindering the practical potential of topological acoustics. Here we overcome these limitations by modulating in time the acoustic properties of a lattice of resonators, introducing the concept of acoustic Floquet topological insulators. We show that acoustic waves provide a fertile ground to apply the anomalous physics of Floquet topological insulators, and demonstrate their relevance for a wide range of acoustic applications, including broadband acoustic isolation and topologically protected, nonreciprocal acoustic emitters.

  18. On the sound insulation of acoustic metasurface using a sub-structuring approach

    Science.gov (United States)

    Yu, Xiang; Lu, Zhenbo; Cheng, Li; Cui, Fangsen

    2017-08-01

    The feasibility of using an acoustic metasurface (AMS) with acoustic stop-band property to realize sound insulation with ventilation function is investigated. An efficient numerical approach is proposed to evaluate its sound insulation performance. The AMS is excited by a reverberant sound source and the standardized sound reduction index (SRI) is numerically investigated. To facilitate the modeling, the coupling between the AMS and the adjacent acoustic fields is formulated using a sub-structuring approach. A modal based formulation is applied to both the source and receiving room, enabling an efficient calculation in the frequency range from 125 Hz to 2000 Hz. The sound pressures and the velocities at the interface are matched by using a transfer function relation based on ;patches;. For illustration purposes, numerical examples are investigated using the proposed approach. The unit cell constituting the AMS is constructed in the shape of a thin acoustic chamber with tailored inner structures, whose stop-band property is numerically analyzed and experimentally demonstrated. The AMS is shown to provide effective sound insulation of over 30 dB in the stop-band frequencies from 600 to 1600 Hz. It is also shown that the proposed approach has the potential to be applied to a broad range of AMS studies and optimization problems.

  19. Evaluation of a low-cost 3D sound system for immersive virtual reality training systems.

    Science.gov (United States)

    Doerr, Kai-Uwe; Rademacher, Holger; Huesgen, Silke; Kubbat, Wolfgang

    2007-01-01

    Since Head Mounted Displays (HMD), datagloves, tracking systems, and powerful computer graphics resources are nowadays in an affordable price range, the usage of PC-based "Virtual Training Systems" becomes very attractive. However, due to the limited field of view of HMD devices, additional modalities have to be provided to benefit from 3D environments. A 3D sound simulation can improve the capabilities of VR systems dramatically. Unfortunately, realistic 3D sound simulations are expensive and demand a tremendous amount of computational power to calculate reverberation, occlusion, and obstruction effects. To use 3D sound in a PC-based training system as a way to direct and guide trainees to observe specific events in 3D space, a cheaper alternative has to be provided, so that a broader range of applications can take advantage of this modality. To address this issue, we focus in this paper on the evaluation of a low-cost 3D sound simulation that is capable of providing traceable 3D sound events. We describe our experimental system setup using conventional stereo headsets in combination with a tracked HMD device and present our results with regard to precision, speed, and used signal types for localizing simulated sound events in a virtual training environment.

  20. 78 FR 13869 - Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy...

    Science.gov (United States)

    2013-03-01

    ...-123-LNG; 12-128-NG; 12-148-NG; 12- 158-NG] Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; CE FLNG, LLC; Consolidated...-NG Puget Sound Energy, Inc Order granting long- term authority to import/export natural gas from/to...

  1. Reconstruction of sound fields with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Walton, Tim

    2014-01-01

    waves traveling in any direction. In particular, rigid sphere microphone arrays are robust, and have the favorable property that the scattering introduced by the array can be compensated for - making the array virtually transparent. This study examines a recently proposed sound field reconstruction...... method based on a point source expansion, i.e. equivalent source method, using a rigid spherical array. The study examines the capability of the method to distinguish between sound waves arriving from different directions (i.e., as a sound field separation method). This is representative of the potential...

  2. Acoustic metamaterials capable of both sound insulation and energy harvesting

    Science.gov (United States)

    Li, Junfei; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

    2016-04-01

    Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.

  3. Acoustic metamaterials capable of both sound insulation and energy harvesting

    International Nuclear Information System (INIS)

    Li, Junfei; Zhou, Xiaoming; Hu, Gengkai; Huang, Guoliang

    2016-01-01

    Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications. (paper)

  4. The Mass of the Black Hole in the Seyfert 1 Galaxy NGC 4593 from Reverberation Mapping

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Bentz, Misty C.; Peterson, Bradley M.

    2006-01-01

    We present new observations leading to an improved black hole mass estimate for the Seyfert 1 galaxy NGC 4593 as part of a reverberation-mapping campaign conducted at the MDM Observatory. Cross-correlation analysis of the H_beta emission-line light curve with the optical continuum light curve...... reveals an emission-line time delay of 3.73 (+-0.75) days. By combining this time delay with the H_beta line width, we derive a central black hole mass of M_BH = 9.8(+-2.1)x10^6 M_sun, an improvement in precision of a factor of several over past results....

  5. Maximum Likelihood PSD Estimation for Speech Enhancement in Reverberation and Noise

    DEFF Research Database (Denmark)

    Kuklasinski, Adam; Doclo, Simon; Jensen, Søren Holdt

    2016-01-01

    In this contribution we focus on the problem of power spectral density (PSD) estimation from multiple microphone signals in reverberant and noisy environments. The PSD estimation method proposed in this paper is based on the maximum likelihood (ML) methodology. In particular, we derive a novel ML...... instrumental measures and is shown to be higher than when the competing estimator is used. Moreover, we perform a speech intelligibility test where we demonstrate that both the proposed and the competing PSD estimators lead to similar intelligibility improvements......., it is shown numerically that the mean squared estimation error achieved by the proposed method is near the limit set by the corresponding Cram´er-Rao lower bound. The speech dereverberation performance of a multi-channel Wiener filter (MWF) based on the proposed PSD estimators is measured using several...

  6. Time delay estimation in a reverberant environment by low rate sampling of impulsive acoustic sources

    KAUST Repository

    Omer, Muhammad

    2012-07-01

    This paper presents a new method of time delay estimation (TDE) using low sample rates of an impulsive acoustic source in a room environment. The proposed method finds the time delay from the room impulse response (RIR) which makes it robust against room reverberations. The RIR is considered a sparse phenomenon and a recently proposed sparse signal reconstruction technique called orthogonal clustering (OC) is utilized for its estimation from the low rate sampled received signal. The arrival time of the direct path signal at a pair of microphones is identified from the estimated RIR and their difference yields the desired time delay. Low sampling rates reduce the hardware and computational complexity and decrease the communication between the microphones and the centralized location. The performance of the proposed technique is demonstrated by numerical simulations and experimental results. © 2012 IEEE.

  7. Sub-sampling-based 2D localization of an impulsive acoustic source in reverberant environments

    KAUST Repository

    Omer, Muhammad

    2014-07-01

    This paper presents a robust method for two-dimensional (2D) impulsive acoustic source localization in a room environment using low sampling rates. The proposed method finds the time delay from the room impulse response (RIR) which makes it robust against room reverberations. We consider the RIR as a sparse phenomenon and apply a recently proposed sparse signal reconstruction technique called orthogonal clustering (OC) for its estimation from the sub-sampled received signal. The arrival time of the direct path signal at a pair of microphones is identified from the estimated RIR, and their difference yields the desired time delay estimate (TDE). Low sampling rates reduces the hardware and computational complexity and decreases the communication between the microphones and the centralized location. Simulation and experimental results of an actual hardware setup are presented to demonstrate the performance of the proposed technique.

  8. Radiated Emissions from a Remote-Controlled Airplane-Measured in a Reverberation Chamber

    Science.gov (United States)

    Ely, Jay J.; Koppen, Sandra V.; Nguyen, Truong X.; Dudley, Kenneth L.; Szatkowski, George N.; Quach, Cuong C.; Vazquez, Sixto L.; Mielnik, John J.; Hogge, Edward F.; Hill, Boyd L.; hide

    2011-01-01

    A full-vehicle, subscale all-electric model airplane was tested for radiated emissions, using a reverberation chamber. The mission of the NASA model airplane is to test in-flight airframe damage diagnosis and battery prognosis algorithms, and provide experimental data for other aviation safety research. Subscale model airplanes are economical experimental tools, but assembling their systems from hobbyist and low-cost components may lead to unforseen electromagnetic compatibility problems. This report provides a guide for accommodating the on-board radio systems, so that all model airplane systems may be operated during radiated emission testing. Radiated emission data are provided for on-board systems being operated separately and together, so that potential interferors can be isolated and mitigated. The report concludes with recommendations for EMI/EMC best practices for subscale model airplanes and airships used for research.

  9. Sub-sampling-based 2D localization of an impulsive acoustic source in reverberant environments

    KAUST Repository

    Omer, Muhammad; Quadeer, Ahmed A; Sharawi, Mohammad S; Al-Naffouri, Tareq Y.

    2014-01-01

    This paper presents a robust method for two-dimensional (2D) impulsive acoustic source localization in a room environment using low sampling rates. The proposed method finds the time delay from the room impulse response (RIR) which makes it robust against room reverberations. We consider the RIR as a sparse phenomenon and apply a recently proposed sparse signal reconstruction technique called orthogonal clustering (OC) for its estimation from the sub-sampled received signal. The arrival time of the direct path signal at a pair of microphones is identified from the estimated RIR, and their difference yields the desired time delay estimate (TDE). Low sampling rates reduces the hardware and computational complexity and decreases the communication between the microphones and the centralized location. Simulation and experimental results of an actual hardware setup are presented to demonstrate the performance of the proposed technique.

  10. A model for calculating specular and diffuse reflections in outdoor sound propagation

    NARCIS (Netherlands)

    Salomons, E.M.

    2006-01-01

    In many practical outdoor situations, the direct sound path between a noise source and a receiver is screened by an obstacle. In these situations indirect sound paths become important, in particular reflections of sound waves. Reflections may occur at objects such as a vertical wall, but also at the

  11. The first-to-zero-sound transition in non-superfluid liquid 4He

    International Nuclear Information System (INIS)

    Woods, A.D.B.; Svensson, E.C.; Martel, P.

    1976-01-01

    Neutron inelastic scattering from 4 He at T=2.3 K shows that for Q -1 'sound-wave' excitations propagate with the characteristics of ordinary or first sound while for Q > approximately 3nm -1 they propagate with the characteristics of zero sound. (Auth.)

  12. Sound field control for a low-frequency test facility

    DEFF Research Database (Denmark)

    Pedersen, Christian Sejer; Møller, Henrik

    2013-01-01

    The two largest problems in controlling the reproduction of low-frequency sound for psychoacoustic experiments is the effect of the room due to standing waves and the relatively large sound pressure levels needed. Anechoic rooms are limited downward in frequency and distortion may be a problem even...... at moderate levels, while pressure-field playback can give higher sound pressures but is limited upwards in frequency. A new solution that addresses both problems has been implemented in the laboratory of Acoustics, Aalborg University. The solution uses one wall with 20 loudspeakers to generate a plane wave...... that is actively absorbed when it reaches the 20 loudspeakers on the opposing wall. This gives a homogeneous sound field in the majority of the room with a flat frequency response in the frequency range 2-300 Hz. The lowest frequencies are limited to sound pressure levels in the order of 95 dB. If larger levels...

  13. Design and Calibration Tests of an Active Sound Intensity Probe

    Directory of Open Access Journals (Sweden)

    Thomas Kletschkowski

    2008-01-01

    Full Text Available The paper presents an active sound intensity probe that can be used for sound source localization in standing wave fields. The probe consists of a sound hard tube that is terminated by a loudspeaker and an integrated pair of microphones. The microphones are used to decompose the standing wave field inside the tube into its incident and reflected part. The latter is cancelled by an adaptive controller that calculates proper driving signals for the loudspeaker. If the open end of the actively controlled tube is placed close to a vibrating surface, the radiated sound intensity can be determined by measuring the cross spectral density between the two microphones. A one-dimensional free field can be realized effectively, as first experiments performed on a simplified test bed have shown. Further tests proved that a prototype of the novel sound intensity probe can be calibrated.

  14. A SOFT X-RAY REVERBERATION LAG IN THE AGN ESO 113–G010

    International Nuclear Information System (INIS)

    Cackett, E. M.; Fabian, A. C.; Kara, E.; Zogbhi, A.; Reynolds, C.; Uttley, P.

    2013-01-01

    Reverberation lags have recently been discovered in a handful of nearby, variable active galactic nuclei (AGNs). Here, we analyze a ∼100 ks archival XMM-Newton observation of the highly variable AGN, ESO 113–G010, in order to search for lags between hard, 1.5-4.5 keV, and soft, 0.3-0.9 keV, energy X-ray bands. At the lowest frequencies available in the light curve (∼ –4 Hz), we find hard lags where the power-law-dominated hard band lags the soft band (where the reflection fraction is high). However, at higher frequencies in the range (2-3) × 10 –4 Hz we find a soft lag of –325 ± 89 s. The general evolution from hard to soft lags as the frequency increases is similar to other AGNs where soft lags have been detected. We interpret this soft lag as due to reverberation from the accretion disk, with the reflection component responding to variability from the X-ray corona. For a black hole mass of 7 × 10 6 M ☉ this corresponds to a light-crossing time of ∼9 R g /c; however, dilution effects mean that the intrinsic lag is likely longer than this. Based on recent black hole mass scaling for lag properties, the lag amplitude and frequency are more consistent with a black hole a few times more massive than the best estimates, though flux-dependent effects could easily add scatter this large.

  15. Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping

    Science.gov (United States)

    Sluse, D.; Tewes, M.

    2014-11-01

    The advent of large area photometric surveys has raised a great deal of interest in the possibility of using broadband photometric data, instead of spectra, to measure the size of the broad line region of active galactic nuclei. We describe here a new method that uses time-delay lensed quasars where one or several images are affected by microlensing due to stars in the lensing galaxy. Because microlensing decreases (or increases) the flux of the continuum compared to the broad line region, it changes the contrast between these two emission components. We show that this effect can be used to effectively disentangle the intrinsic variability of those two regions, offering the opportunity to perform reverberation mapping based on single-band photometric data. Based on simulated light curves generated using a damped random walk model of quasar variability, we show that measurement of the size of the broad line region can be achieved using this method, provided one spectrum has been obtained independently during the monitoring. This method is complementary to photometric reverberation mapping and could also be extended to multi-band data. Because the effect described above produces a variability pattern in difference light curves between pairs of lensed images that is correlated with the time-lagged continuum variability, it can potentially produce systematic errors in measurement of time delays between pairs of lensed images. Simple simulations indicate that time-delay measurement techniques that use a sufficiently flexible model for the extrinsic variability are not affected by this effect and produce accurate time delays.

  16. Using iron line reverberation and spectroscopy to distinguish Kerr and non-Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jiachen; Bambi, Cosimo [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 220 Handan Road, 200433 Shanghai (China); Steiner, James F., E-mail: jcjiang12@fudan.edu.cn, E-mail: bambi@fudan.edu.cn, E-mail: jsteiner@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-05-01

    The iron Kα line commonly observed in the X-ray spectrum of both stellar-mass and supermassive black hole candidates is produced by the illumination of a cold accretion disk by a hot corona. In this framework, the activation of a new flaring region in the hot corona imprints a time variation on the iron line spectrum. Future X-ray facilities with high time resolution and large effective areas may be able to measure the so-called 2-dimensional transfer function; that is, the iron line profile detected by a distant observer as a function of time in response to an instantaneous flare from the X-ray primary source. This work is a preliminary study to determine if and how such a technique can provide more information about the spacetime geometry around the compact object than the already possible measurements of the time-integrated iron line profile. Within our simplified model, we find that a measurement of iron line reverberation can improve constraints appreciably given a sufficiently strong signal, though that most of the information is present in the time-integrated spectrum. Our aim is to test the Kerr metric. We find that current X-ray facilities and data are unable to provide strong tests of the Kerr nature of supermassive black hole candidates. We consider an optimistic case of 10{sup 5} iron line photons from a next-generation data set. With such data, the reverberation model improves upon the spectral constraint by an order of magnitude.

  17. Sound Insulation between Dwellings

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2011-01-01

    Regulatory sound insulation requirements for dwellings exist in more than 30 countries in Europe. In some countries, requirements have existed since the 1950s. Findings from comparative studies show that sound insulation descriptors and requirements represent a high degree of diversity...... and initiate – where needed – improvement of sound insulation of new and existing dwellings in Europe to the benefit of the inhabitants and the society. A European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs...... 2009-2013. The main objectives of TU0901 are to prepare proposals for harmonized sound insulation descriptors and for a European sound classification scheme with a number of quality classes for dwellings. Findings from the studies provide input for the discussions in COST TU0901. Data collected from 24...

  18. Third sound in a restricted geometry

    International Nuclear Information System (INIS)

    Brouwer, P.W.; Draisma, W.A.; Pinkse, P.W.H.; Beelen, H. van; Jochemsen, R.; Frossati, G.

    1992-01-01

    Bergman's general treatment of third sound waves has been extended to a (restricted) parallel plate geometry. In a parallel plate geometry two independent third sound modes can propagate: a symmetric and an antisymmetric one. Calculations show that at temperatures below 1 K the antisymmetric mode carries the most important part of the temperature amplitude. Because of the relatively strong substrate influence the temperature amplitude of the symmetric mode is suppressed. The ΔT/Δh versus T measurements by Laheurte et al. and of the ΔT/Δh versus ω measurements by Ellis et al. are explained. 7 refs., 2 figs

  19. Sound beam manipulation based on temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Feng [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Quan, Li; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-10-28

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

  20. Upconversion of ion-sound to Langmuir turbulence

    International Nuclear Information System (INIS)

    Vlahos, L.; Papadopoulos, K.

    1979-01-01

    It is shown that upconversion of ion sound to Langmuir waves is impossible in a plasma with upsilon/sub d/< upsilon/sub e/. Previous conclusions to the opposite were in error, owing to neglect of the reverse process (i.e., reabsorbtion of Langmuir waves), which always dominates for upsilon/sub d/< upsilon/sub e/

  1. The velocity of sound

    International Nuclear Information System (INIS)

    Beyer, R.T.

    1985-01-01

    The paper reviews the work carried out on the velocity of sound in liquid alkali metals. The experimental methods to determine the velocity measurements are described. Tables are presented of reported data on the velocity of sound in lithium, sodium, potassium, rubidium and caesium. A formula is given for alkali metals, in which the sound velocity is a function of shear viscosity, atomic mass and atomic volume. (U.K.)

  2. Michael Jackson's Sound Stages

    OpenAIRE

    Morten Michelsen

    2012-01-01

    In order to discuss analytically spatial aspects of recorded sound William Moylan’s concept of ‘sound stage’ is developed within a musicological framework as part of a sound paradigm which includes timbre, texture and sound stage. Two Michael Jackson songs (‘The Lady in My Life’ from 1982 and ‘Scream’ from 1995) are used to: a) demonstrate the value of such a conceptualisation, and b) demonstrate that the model has its limits, as record producers in the 1990s began ignoring the conventions of...

  3. What is Sound?

    OpenAIRE

    Nelson, Peter

    2014-01-01

    What is sound? This question is posed in contradiction to the every-day understanding that sound is a phenomenon apart from us, to be heard, made, shaped and organised. Thinking through the history of computer music, and considering the current configuration of digital communi-cations, sound is reconfigured as a type of network. This network is envisaged as non-hierarchical, in keeping with currents of thought that refuse to prioritise the human in the world. The relationship of sound to musi...

  4. Light and Sound

    CERN Document Server

    Karam, P Andrew

    2010-01-01

    Our world is largely defined by what we see and hear-but our uses for light and sound go far beyond simply seeing a photo or hearing a song. A concentrated beam of light, lasers are powerful tools used in industry, research, and medicine, as well as in everyday electronics like DVD and CD players. Ultrasound, sound emitted at a high frequency, helps create images of a developing baby, cleans teeth, and much more. Light and Sound teaches how light and sound work, how they are used in our day-to-day lives, and how they can be used to learn about the universe at large.

  5. Early Sound Symbolism for Vowel Sounds

    Directory of Open Access Journals (Sweden)

    Ferrinne Spector

    2013-06-01

    Full Text Available Children and adults consistently match some words (e.g., kiki to jagged shapes and other words (e.g., bouba to rounded shapes, providing evidence for non-arbitrary sound–shape mapping. In this study, we investigated the influence of vowels on sound–shape matching in toddlers, using four contrasting pairs of nonsense words differing in vowel sound (/i/ as in feet vs. /o/ as in boat and four rounded–jagged shape pairs. Crucially, we used reduplicated syllables (e.g., kiki vs. koko rather than confounding vowel sound with consonant context and syllable variability (e.g., kiki vs. bouba. Toddlers consistently matched words with /o/ to rounded shapes and words with /i/ to jagged shapes (p < 0.01. The results suggest that there may be naturally biased correspondences between vowel sound and shape.

  6. THE LICK AGN MONITORING PROJECT: THE M BH-σ* RELATION FOR REVERBERATION-MAPPED ACTIVE GALAXIES

    International Nuclear Information System (INIS)

    Woo, Jong-Hak; Treu, Tommaso; Bennert, Vardha N.; Barth, Aaron J.; Walsh, Jonelle L.; Bentz, Misty C.; Wright, Shelley A.; Filippenko, Alexei V.; Li, Weidong; Martini, Paul; Canalizo, Gabriela; Gates, Elinor; Greene, Jenny; Malkan, Matthew A.; Stern, Daniel; Minezaki, Takeo

    2010-01-01

    To investigate the black hole mass versus stellar velocity dispersion (M BH -σ * ) relation of active galaxies, we measured the velocity dispersions of a sample of local Seyfert 1 galaxies, for which we have recently determined black hole masses using reverberation mapping. For most objects, stellar velocity dispersions were measured from high signal-to-noise ratio optical spectra centered on the Ca II triplet region (∼8500 A), obtained at the Keck, Palomar, and Lick Observatories. For two objects, in which the Ca II triplet region was contaminated by nuclear emission, the measurement was based on high-quality H-band spectra obtained with the OH-Suppressing Infrared Imaging Spectrograph at the Keck-II telescope. Combining our new measurements with data from the literature, we assemble a sample of 24 active galaxies with stellar velocity dispersions and reverberation-based black hole mass measurements in the range of black hole mass 10 6 BH /M sun 9 . We use this sample to obtain reverberation-mapping constraints on the slope and intrinsic scatter of the M BH -σ * relation of active galaxies. Assuming a constant virial coefficient f for the reverberation-mapping black hole masses, we find a slope β = 3.55 ± 0.60 and the intrinsic scatter σ int = 0.43 ± 0.08 dex in the relation log(M BH /M sun ) = α + β log(σ * /200 km s -1 ), which are consistent with those found for quiescent galaxies. We derive an updated value of the virial coefficient f by finding the value which places the reverberation masses in best agreement with the M BH -σ * relation of quiescent galaxies; using the quiescent M BH -σ * relation determined by Gueltekin et al., we find log f = 0.72 +0.09 -0.10 with an intrinsic scatter of 0.44 ± 0.07 dex. No strong correlations between f and parameters connected to the physics of accretion (such as the Eddington ratio or line-shape measurements) are found. The uncertainty of the virial coefficient remains one of the main sources of the

  7. InfoSound

    DEFF Research Database (Denmark)

    Sonnenwald, Diane H.; Gopinath, B.; Haberman, Gary O.

    1990-01-01

    The authors explore ways to enhance users' comprehension of complex applications using music and sound effects to present application-program events that are difficult to detect visually. A prototype system, Infosound, allows developers to create and store musical sequences and sound effects with...

  8. Sound propagation in cities

    NARCIS (Netherlands)

    Salomons, E.; Polinder, H.; Lohman, W.; Zhou, H.; Borst, H.

    2009-01-01

    A new engineering model for sound propagation in cities is presented. The model is based on numerical and experimental studies of sound propagation between street canyons. Multiple reflections in the source canyon and the receiver canyon are taken into account in an efficient way, while weak

  9. OMNIDIRECTIONAL SOUND SOURCE

    DEFF Research Database (Denmark)

    1996-01-01

    A sound source comprising a loudspeaker (6) and a hollow coupler (4) with an open inlet which communicates with and is closed by the loudspeaker (6) and an open outlet, said coupler (4) comprising rigid walls which cannot respond to the sound pressures produced by the loudspeaker (6). According...

  10. Hamiltonian Algorithm Sound Synthesis

    OpenAIRE

    大矢, 健一

    2013-01-01

    Hamiltonian Algorithm (HA) is an algorithm for searching solutions is optimization problems. This paper introduces a sound synthesis technique using Hamiltonian Algorithm and shows a simple example. "Hamiltonian Algorithm Sound Synthesis" uses phase transition effect in HA. Because of this transition effect, totally new waveforms are produced.

  11. Poetry Pages. Sound Effects.

    Science.gov (United States)

    Fina, Allan de

    1992-01-01

    Explains how elementary teachers can help students understand onomatopoeia, suggesting that they define onomatopoeia, share examples of it, read poems and have students discuss onomatopoeic words, act out common household sounds, write about sound effects, and create choral readings of onomatopoeic poems. Two appropriate poems are included. (SM)

  12. Exploring Noise: Sound Pollution.

    Science.gov (United States)

    Rillo, Thomas J.

    1979-01-01

    Part one of a three-part series about noise pollution and its effects on humans. This section presents the background information for teachers who are preparing a unit on sound. The next issues will offer learning activities for measuring the effects of sound and some references. (SA)

  13. Sounds of a Star

    Science.gov (United States)

    2001-06-01

    Acoustic Oscillations in Solar-Twin "Alpha Cen A" Observed from La Silla by Swiss Team Summary Sound waves running through a star can help astronomers reveal its inner properties. This particular branch of modern astrophysics is known as "asteroseismology" . In the case of our Sun, the brightest star in the sky, such waves have been observed since some time, and have greatly improved our knowledge about what is going on inside. However, because they are much fainter, it has turned out to be very difficult to detect similar waves in other stars. Nevertheless, tiny oscillations in a solar-twin star have now been unambiguously detected by Swiss astronomers François Bouchy and Fabien Carrier from the Geneva Observatory, using the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory. This telescope is mostly used for discovering exoplanets (see ESO PR 07/01 ). The star Alpha Centauri A is the nearest star visible to the naked eye, at a distance of a little more than 4 light-years. The new measurements show that it pulsates with a 7-minute cycle, very similar to what is observed in the Sun . Asteroseismology for Sun-like stars is likely to become an important probe of stellar theory in the near future. The state-of-the-art HARPS spectrograph , to be mounted on the ESO 3.6-m telescope at La Silla, will be able to search for oscillations in stars that are 100 times fainter than those for which such demanding observations are possible with CORALIE. PR Photo 23a/01 : Oscillations in a solar-like star (schematic picture). PR Photo 23b/01 : Acoustic spectrum of Alpha Centauri A , as observed with CORALIE. Asteroseismology: listening to the stars ESO PR Photo 23a/01 ESO PR Photo 23a/01 [Preview - JPEG: 357 x 400 pix - 96k] [Normal - JPEG: 713 x 800 pix - 256k] [HiRes - JPEG: 2673 x 3000 pix - 2.1Mb Caption : PR Photo 23a/01 is a graphical representation of resonating acoustic waves in the interior of a solar-like star. Red and blue

  14. Sound classification of dwellings

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2012-01-01

    National schemes for sound classification of dwellings exist in more than ten countries in Europe, typically published as national standards. The schemes define quality classes reflecting different levels of acoustical comfort. Main criteria concern airborne and impact sound insulation between...... dwellings, facade sound insulation and installation noise. The schemes have been developed, implemented and revised gradually since the early 1990s. However, due to lack of coordination between countries, there are significant discrepancies, and new standards and revisions continue to increase the diversity...... is needed, and a European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs 2009-2013, one of the main objectives being to prepare a proposal for a European sound classification scheme with a number of quality...

  15. Evidence for a common scale O(0.1) m that controls seabed scattering and reverberation in shallow water.

    Science.gov (United States)

    Holland, Charles W

    2012-10-01

    Analysis of the spectral content of long-range reverberation yields two observations. First, there is a remarkably similar scale, O(0.1) m, between three diverse continental shelf regions. This is surprising given the complexity and diversity of geologic processes. Second, there is strong evidence that the scale is associated with heterogeneities within the sediment. Thus, sediment volume scattering, not interface scattering, controls long-range reverberation from a few hundred hertz to several kilohertz. This is also unexpected given that at long ranges the vertical grazing angles are less than the critical angle, and hence the penetration of the acoustic field into the sub-bottom is expected to be modest. The consistency of the scale, O(0.1) m, suggests an underlying feature or mechanism that is consistent across many ostensibly diverse geological settings. Neither the feature nor mechanism is known at this time.

  16. Sound propagation in elongated superfluid fermionic clouds

    International Nuclear Information System (INIS)

    Capuzzi, P.; Vignolo, P.; Federici, F.; Tosi, M. P.

    2006-01-01

    We use hydrodynamic equations to study sound propagation in a superfluid Fermi gas at zero temperature inside a strongly elongated cigar-shaped trap, with main attention to the transition from the BCS to the unitary regime. First, we treat the role of the radial density profile in the limit of a cylindrical geometry and then evaluate numerically the effect of the axial confinement in a configuration in which a hole is present in the gas density at the center of the trap. We find that in a strongly elongated trap the speed of sound in both the BCS and the unitary regime differs by a factor √(3/5) from that in a homogeneous three-dimensional superfluid. The predictions of the theory could be tested by measurements of sound-wave propagation in a setup such as that exploited by Andrews et al. [Phys. Rev. Lett. 79, 553 (1997)] for an atomic Bose-Einstein condensate

  17. Sound analysis of a cup drum

    International Nuclear Information System (INIS)

    Kim, Kun ho

    2012-01-01

    The International Young Physicists’ Tournament (IYPT) is a worldwide tournament that evaluates a high-school student's ability to solve various physics conundrums that have not been fully resolved in the past. The research presented here is my solution to the cup drum problem. The physics behind a cup drum has never been explored or modelled. A cup drum is a musical instrument that can generate different frequencies and amplitudes depending on the location of a cup held upside-down over, on or under a water surface. The tapping sound of a cup drum can be divided into two components: standing waves and plate vibration. By individually researching the nature of these two sounds, I arrived at conclusions that could accurately predict the frequencies in most cases. When the drum is very close to the surface, qualitative explanations are given. In addition, I examined the trend of the tapping sound amplitude at various distances and qualitatively explained the experimental results. (paper)

  18. Sound transmission loss of composite sandwich panels

    Science.gov (United States)

    Zhou, Ran

    Light composite sandwich panels are increasingly used in automobiles, ships and aircraft, because of the advantages they offer of high strength-to-weight ratios. However, the acoustical properties of these light and stiff structures can be less desirable than those of equivalent metal panels. These undesirable properties can lead to high interior noise levels. A number of researchers have studied the acoustical properties of honeycomb and foam sandwich panels. Not much work, however, has been carried out on foam-filled honeycomb sandwich panels. In this dissertation, governing equations for the forced vibration of asymmetric sandwich panels are developed. An analytical expression for modal densities of symmetric sandwich panels is derived from a sixth-order governing equation. A boundary element analysis model for the sound transmission loss of symmetric sandwich panels is proposed. Measurements of the modal density, total loss factor, radiation loss factor, and sound transmission loss of foam-filled honeycomb sandwich panels with different configurations and thicknesses are presented. Comparisons between the predicted sound transmission loss values obtained from wave impedance analysis, statistical energy analysis, boundary element analysis, and experimental values are presented. The wave impedance analysis model provides accurate predictions of sound transmission loss for the thin foam-filled honeycomb sandwich panels at frequencies above their first resonance frequencies. The predictions from the statistical energy analysis model are in better agreement with the experimental transmission loss values of the sandwich panels when the measured radiation loss factor values near coincidence are used instead of the theoretical values for single-layer panels. The proposed boundary element analysis model provides more accurate predictions of sound transmission loss for the thick foam-filled honeycomb sandwich panels than either the wave impedance analysis model or the

  19. Shallow water acoustic backscatter and reverberation measurements using a 68-kHz cylindrical array: a dissertation

    OpenAIRE

    Gallaudet, Timothy C. (Timothy Cole), 1967-

    2001-01-01

    The characterization of high frequency, shallow water acoustic backscatter and reverberation is important because acoustic systems are used in many scientific, commercial, and military applications. The approach taken is to use data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz multibeam sonar capable of 360 deg imaging in a vertical plane perpendicular to its direction of travel. With this unique capability, acoustic backscatter imagery of the seafloor, sea surface, and hori...

  20. The sound manifesto

    Science.gov (United States)

    O'Donnell, Michael J.; Bisnovatyi, Ilia

    2000-11-01

    Computing practice today depends on visual output to drive almost all user interaction. Other senses, such as audition, may be totally neglected, or used tangentially, or used in highly restricted specialized ways. We have excellent audio rendering through D-A conversion, but we lack rich general facilities for modeling and manipulating sound comparable in quality and flexibility to graphics. We need coordinated research in several disciplines to improve the use of sound as an interactive information channel. Incremental and separate improvements in synthesis, analysis, speech processing, audiology, acoustics, music, etc. will not alone produce the radical progress that we seek in sonic practice. We also need to create a new central topic of study in digital audio research. The new topic will assimilate the contributions of different disciplines on a common foundation. The key central concept that we lack is sound as a general-purpose information channel. We must investigate the structure of this information channel, which is driven by the cooperative development of auditory perception and physical sound production. Particular audible encodings, such as speech and music, illuminate sonic information by example, but they are no more sufficient for a characterization than typography is sufficient for characterization of visual information. To develop this new conceptual topic of sonic information structure, we need to integrate insights from a number of different disciplines that deal with sound. In particular, we need to coordinate central and foundational studies of the representational models of sound with specific applications that illuminate the good and bad qualities of these models. Each natural or artificial process that generates informative sound, and each perceptual mechanism that derives information from sound, will teach us something about the right structure to attribute to the sound itself. The new Sound topic will combine the work of computer

  1. SWIFT/UVOT GRISM MONITORING OF NGC 5548 IN 2013: AN ATTEMPT AT Mg ii REVERBERATION MAPPING

    Energy Technology Data Exchange (ETDEWEB)

    Cackett, E. M.; Troyer, J. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock St, Detroit, MI 48201 (United States); Gültekin, K. [Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Fausnaugh, M. M.; Peterson, B. M. [Department of Astronomy, The Ohio State University, 140 West 18th Ave, Columbus, OH 43210 (United States); Vestergaard, M., E-mail: ecackett@wayne.edu [Dark Cosmology Centre, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark)

    2015-09-10

    Reverberation-mapping-based scaling relations are often used to estimate the masses of black holes from single-epoch spectra of active galactic nuclei (AGNs). While the radius–luminosity relation that is the basis of these scaling relations is determined using reverberation mapping of the Hβ line in nearby AGNs, the scaling relations are often extended to use other broad emission lines, such as Mg ii, in order to get black hole masses at higher redshifts when Hβ is redshifted out of the optical waveband. However, there is no radius–luminosity relation determined directly from Mg ii. Here, we present an attempt to perform reverberation mapping using Mg ii in the well-studied nearby Seyfert 1 NGC 5548. We used Swift to obtain UV grism spectra of NGC 5548 once every two days from 2013 April to September. Concurrent photometric UV monitoring with Swift provides a well determined continuum light curve that shows strong variability. The Mg ii emission line, however, is not strongly correlated with the continuum variability, and there is no significant lag between the two. We discuss these results in the context of using Mg ii scaling relations to estimate high-redshift black hole masses.

  2. Shallow water acoustic backscatter and reverberation measurements using a 68-kHz cylindrical array

    Science.gov (United States)

    Gallaudet, Timothy Cole

    2001-10-01

    The characterization of high frequency, shallow water acoustic backscatter and reverberation is important because acoustic systems are used in many scientific, commercial, and military applications. The approach taken is to use data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz multibeam sonar capable of 360° imaging in a vertical plane perpendicular to its direction of travel. With this unique capability, acoustic backscatter imagery of the seafloor, sea surface, and horizontal and vertical planes in the volume are constructed from data obtained in 200m deep waters in the Northeastern Gulf of Mexico when the TVSS was towed 78m below the surface, 735m astern of a towship. The processed imagery provide a quasi-synoptic characterization of the spatial and temporal structure of boundary and volume acoustic backscatter and reverberation. Diffraction, element patterns, and high sidelobe levels are shown to be the most serious problems affecting cylindrical arrays such as the TVSS, and an amplitude shading method is presented for reducing the peak sidelobe levels of irregular-line and non-coplanar arrays. Errors in the towfish's attitude and motion sensor, and irregularities in the TVSS's transmitted beampattern produce artifacts in the TVSS-derived bathymetry and seafloor acoustic backscatter imagery. Correction strategies for these problems are described, which are unique in that they use environmental information extracted from both ocean boundaries. Sea surface and volume acoustic backscatter imagery are used to explore and characterize the structure of near-surface bubble clouds, schooling fish, and zooplankton. The simultaneous horizontal and vertical coverage provided by the TVSS is shown to be a primary advantage, motivating further use of multibeam sonars in these applications. Whereas boundary backscatter fluctuations are well described by Weibull, K, and Rayleigh mixture probability distributions, those corresponding to volume backscatter are

  3. Sound transmission in porcine thorax through airway insonification

    Science.gov (United States)

    Dai, Zoujun; Mansy, Hansen A.; Henry, Brian M.; Sandler, Richard H.; Balk, Robert A.; Royston, Thomas J.

    2015-01-01

    Many pulmonary injuries and pathologies may lead to structural and functional changes in the lungs resulting in measurable sound transmission changes on the chest surface. Additionally, noninvasive imaging of externally driven mechanical wave motion in the chest (e.g., using magnetic resonance elastography) can provide information about lung structural property changes and, hence, may be of diagnostic value. In the present study, a comprehensive computational simulation (in silico) model was developed to simulate sound wave propagation in the airways, lung, and chest wall under normal and pneumothorax conditions. Experiments were carried out to validate the model. Here, sound waves with frequency content from 50 to 700 Hz were introduced into airways of five porcine subjects via an endotracheal tube, and transmitted waves were measured by scanning laser Doppler vibrometry at the chest wall surface. The computational model predictions of decreased sound transmission with pneumothorax were consistent with experimental measurements. The in silico model can also be used to visualize wave propagation inside and on the chest wall surface for other pulmonary pathologies, which may help in developing and interpreting diagnostic procedures that utilize sound and vibration. PMID:26280512

  4. Sound transmission in porcine thorax through airway insonification.

    Science.gov (United States)

    Peng, Ying; Dai, Zoujun; Mansy, Hansen A; Henry, Brian M; Sandler, Richard H; Balk, Robert A; Royston, Thomas J

    2016-04-01

    Many pulmonary injuries and pathologies may lead to structural and functional changes in the lungs resulting in measurable sound transmission changes on the chest surface. Additionally, noninvasive imaging of externally driven mechanical wave motion in the chest (e.g., using magnetic resonance elastography) can provide information about lung structural property changes and, hence, may be of diagnostic value. In the present study, a comprehensive computational simulation (in silico) model was developed to simulate sound wave propagation in the airways, lung, and chest wall under normal and pneumothorax conditions. Experiments were carried out to validate the model. Here, sound waves with frequency content from 50 to 700 Hz were introduced into airways of five porcine subjects via an endotracheal tube, and transmitted waves were measured by scanning laser Doppler vibrometry at the chest wall surface. The computational model predictions of decreased sound transmission with pneumothorax were consistent with experimental measurements. The in silico model can also be used to visualize wave propagation inside and on the chest wall surface for other pulmonary pathologies, which may help in developing and interpreting diagnostic procedures that utilize sound and vibration.

  5. Acoustic Metacages for Omnidirectional Sound Shielding

    OpenAIRE

    Shen, Chen; Xie, Yangbo; Li, Junfei; Cummer, Steven A.; Jing, Yun

    2017-01-01

    Conventional sound shielding structures typically prevent fluid transport between the exterior and interior. A design of a two-dimensional acoustic metacage with subwavelength thickness which can shield acoustic waves from all directions while allowing steady fluid flow is presented in this paper. The structure is designed based on acoustic gradient-index metasurfaces composed of open channels and shunted Helmholtz resonators. The strong parallel momentum on the metacage surface rejects in-pl...

  6. Digitizing a sound archive

    DEFF Research Database (Denmark)

    Cone, Louise

    2017-01-01

    Danish and international artists. His methodology left us with a large collection of unique and inspirational time-based media sound artworks that have, until very recently, been inaccessible. Existing on an array of different media formats, such as open reel tapes, 8-track and 4 track cassettes, VHS......In 1990 an artist by the name of William Louis Sørensen was hired by the National Gallery of Denmark to collect important works of art – made from sound. His job was to acquire sound art, but also recordings that captured rare artistic occurrences, music, performances and happenings from both...

  7. Focused sound: oncological therapy for transformed tissue

    International Nuclear Information System (INIS)

    Mares, C. E.; Cordova F, T.; Hernandez, A.

    2017-10-01

    The restlessness of the human being involves observing and being critical through their senses, in particular a disturbance in the environment cause vibrations that can be registered by the sense of hearing through the eardrum, if what it produces is in the frequency of the audible sound. The distinction of the sound of the other forms of energy transfer is that the waves of the same quickly involve the progressive return of displacements or vibrations of the molecules in the medium that propagates. In this work a sweep of frequencies was made from infra sound to ultrasound in plants of different types with different thicknesses and two people in order to find the resonance of each of them and compare it with the resonances registered in text, which allowed evaluate the secondary effect of sound focused on the tissue of the leaves and in particular of people. We consider that there is potential for this focused sound modality if it is at the resonance frequency of the transformed tissue as a means of oncological therapy without affecting the neighboring cells. (Author)

  8. Baffling or Baffled: Improve Your Acoustics.

    Science.gov (United States)

    Abdoo, Frank B.

    1981-01-01

    Presents techniques for evaluating the acoustics (reverberation time, and standing waves and resonance phenomena) of a band performance room. Gives instructions for building and placing inexpensive baffles (free-standing, portable sound barriers) to correct room defects. (SJL)

  9. Development of application technology of ultrasonic wave sensor; Choonpa sensor oyo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hosoya, H; Hikita, N; Sasaki, H; Kore, H [Mazda Motor Corp., Hiroshima (Japan)

    1997-10-01

    We have developed parking assist system, which informs a driver the closing point and distance to the objects such as other vehicle, wall and pole around the own vehicle at parking area and makes parking maneuverability easy. This system is based on the range detection technology using ultrasonic wave sensor. We have improved the detecting ability in short range of about 20cm by reducing the reverberation of transmitting wave signal and controlling sensitivities of signal intensity and threshold line. We will show mainly the improvement of short range detection of ultrasonic wave sensor, and briefly the performance of parking assist system. 1 ref., 14 figs., 1 tab.

  10. Waves in Strong Centrifugal Field

    Science.gov (United States)

    Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.

    Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of 106g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarization and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modeling of the wave dynamics with the analytical predictions is performed. New phenomena of the resonances in the GC is found. The resonances occur for the waves polarized along the rotational axis having the smallest dumping due to the viscosity.

  11. A NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING

    International Nuclear Information System (INIS)

    Li, Yan-Rong; Wang, Jian-Min; Bai, Jin-Ming

    2016-01-01

    Broad emission lines of active galactic nuclei stem from a spatially extended region (broad-line region, BLR) that is composed of discrete clouds and photoionized by the central ionizing continuum. The temporal behaviors of these emission lines are blurred echoes of continuum variations (i.e., reverberation mapping, RM) and directly reflect the structures and kinematic information of BLRs through the so-called transfer function (also known as the velocity-delay map). Based on the previous works of Rybicki and Press and Zu et al., we develop an extended, non-parametric approach to determine the transfer function for RM data, in which the transfer function is expressed as a sum of a family of relatively displaced Gaussian response functions. Therefore, arbitrary shapes of transfer functions associated with complicated BLR geometry can be seamlessly included, enabling us to relax the presumption of a specified transfer function frequently adopted in previous studies and to let it be determined by observation data. We formulate our approach in a previously well-established framework that incorporates the statistical modeling of continuum variations as a damped random walk process and takes into account long-term secular variations which are irrelevant to RM signals. The application to RM data shows the fidelity of our approach.

  12. A NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan-Rong; Wang, Jian-Min [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China); Bai, Jin-Ming, E-mail: liyanrong@mail.ihep.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)

    2016-11-10

    Broad emission lines of active galactic nuclei stem from a spatially extended region (broad-line region, BLR) that is composed of discrete clouds and photoionized by the central ionizing continuum. The temporal behaviors of these emission lines are blurred echoes of continuum variations (i.e., reverberation mapping, RM) and directly reflect the structures and kinematic information of BLRs through the so-called transfer function (also known as the velocity-delay map). Based on the previous works of Rybicki and Press and Zu et al., we develop an extended, non-parametric approach to determine the transfer function for RM data, in which the transfer function is expressed as a sum of a family of relatively displaced Gaussian response functions. Therefore, arbitrary shapes of transfer functions associated with complicated BLR geometry can be seamlessly included, enabling us to relax the presumption of a specified transfer function frequently adopted in previous studies and to let it be determined by observation data. We formulate our approach in a previously well-established framework that incorporates the statistical modeling of continuum variations as a damped random walk process and takes into account long-term secular variations which are irrelevant to RM signals. The application to RM data shows the fidelity of our approach.

  13. Differential consolidation and pattern reverberations within episodic cell assemblies in the mouse hippocampus.

    Directory of Open Access Journals (Sweden)

    Remus Oşan

    2011-02-01

    Full Text Available One hallmark feature of consolidation of episodic memory is that only a fraction of original information, which is usually in a more abstract form, is selected for long-term memory storage. How does the brain perform these differential memory consolidations? To investigate the neural network mechanism that governs this selective consolidation process, we use a set of distinct fearful events to study if and how hippocampal CA1 cells engage in selective memory encoding and consolidation. We show that these distinct episodes activate a unique assembly of CA1 episodic cells, or neural cliques, whose response-selectivity ranges from general-to-specific features. A series of parametric analyses further reveal that post-learning CA1 episodic pattern replays or reverberations are mostly mediated by cells exhibiting event intensity-invariant responses, not by the intensity-sensitive cells. More importantly, reactivation cross-correlations displayed by intensity-invariant cells encoding general episodic features during immediate post-learning period tend to be stronger than those displayed by invariant cells encoding specific features. These differential reactivations within the CA1 episodic cell populations can thus provide the hippocampus with a selection mechanism to consolidate preferentially more generalized knowledge for long-term memory storage.

  14. A Radio Frequency Radiation Exposure System for Rodents based on Reverberation Chambers.

    Science.gov (United States)

    Capstick, Myles; Kuster, Niels; Kuehn, Sven; Berdinas-Torres, Veronica; Gong, Yijian; Wilson, Perry; Ladbury, John; Koepke, Galen; McCormick, David L; Gauger, James; Melnick, Ronald L

    2017-08-01

    In this paper we present the novel design features, their technical implementation, and an evaluation of the radio Frequency (RF) exposure systems developed for the National Toxicology Program (NTP) of the National Institute of Environmental Health Sciences (NIEHS) studies on the potential toxicity and carcinogenicity of 2nd and 3rd generation mobile-phone signals. The system requirements for this 2-year NTP cancer bioassay study were the tightly-controlled lifetime exposure of rodents (1568 rats and 1512 mice) to three power levels plus sham simulating typical daily, and higher, exposures of users of GSM and CDMA (IS95) signals. Reverberation chambers and animal housing were designed to allow extended exposure time per day for free-roaming individually-housed animals. The performance of the chamber was characterized in terms of homogeneity, stirred to unstirred energy, efficiency. The achieved homogeneity was 0.59 dB and 0.48 dB at 900 and 1900 MHz respectively. The temporal variation in the electric field strength was optimized to give similar characteristics to that of the power control of a phone in a real network using the two stirrers. Experimental dosimetry was performed to validate the SAR sensitivity and determine the SAR uniformity throughout the exposure volume; SAR uniformities of 0.46 dB and 0.40 dB, respectively, for rats and mice were achieved.

  15. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: RAPID C iv BROAD ABSORPTION LINE VARIABILITY

    International Nuclear Information System (INIS)

    Grier, C. J.; Brandt, W. N.; Trump, J. R.; Schneider, D. P.; Hall, P. B.; Shen, Yue; Vivek, M.; Dawson, K. S.; Ak, N. Filiz; Chen, Yuguang; Denney, K. D.; Kochanek, C. S.; Peterson, B. M.; Green, Paul J.; Jiang, Linhua; McGreer, Ian D.; Pâris, I.; Tao, Charling; Wood-Vasey, W. M.; Bizyaev, Dmitry

    2015-01-01

    We report the discovery of rapid variations of a high-velocity C iv broad absorption line trough in the quasar SDSS J141007.74+541203.3. This object was intensively observed in 2014 as a part of the Sloan Digital Sky Survey Reverberation Mapping Project, during which 32 epochs of spectroscopy were obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We observe significant (>4σ) variability in the equivalent width (EW) of the broad (∼4000 km s −1 wide) C iv trough on rest-frame timescales as short as 1.20 days (∼29 hr), the shortest broad absorption line variability timescale yet reported. The EW varied by ∼10% on these short timescales, and by about a factor of two over the duration of the campaign. We evaluate several potential causes of the variability, concluding that the most likely cause is a rapid response to changes in the incident ionizing continuum. If the outflow is at a radius where the recombination rate is higher than the ionization rate, the timescale of variability places a lower limit on the density of the absorbing gas of n e ≳ 3.9 × 10 5 cm −3 . The broad absorption line variability characteristics of this quasar are consistent with those observed in previous studies of quasars, indicating that such short-term variability may in fact be common and thus can be used to learn about outflow characteristics and contributions to quasar/host-galaxy feedback scenarios

  16. Development of an Acoustic Localization Method for Cavitation Experiments in Reverberant Environments

    Science.gov (United States)

    Ranjeva, Minna; Thompson, Lee; Perlitz, Daniel; Bonness, William; Capone, Dean; Elbing, Brian

    2011-11-01

    Cavitation is a major concern for the US Navy since it can cause ship damage and produce unwanted noise. The ability to precisely locate cavitation onset in laboratory scale experiments is essential for proper design that will minimize this undesired phenomenon. Measuring the cavitation onset is more accurately determined acoustically than visually. However, if other parts of the model begin to cavitate prior to the component of interest the acoustic data is contaminated with spurious noise. Consequently, cavitation onset is widely determined by optically locating the event of interest. The current research effort aims at developing an acoustic localization scheme for reverberant environments such as water tunnels. Currently cavitation bubbles are being induced in a static water tank with a laser, allowing the localization techniques to be refined with the bubble at a known location. The source is located with the use of acoustic data collected with hydrophones and analyzed using signal processing techniques. To verify the accuracy of the acoustic scheme, the events are simultaneously monitored visually with the use of a high speed camera. Once refined testing will be conducted in a water tunnel. This research was sponsored by the Naval Engineering Education Center (NEEC).

  17. Sounds of Web Advertising

    DEFF Research Database (Denmark)

    Jessen, Iben Bredahl; Graakjær, Nicolai Jørgensgaard

    2010-01-01

    Sound seems to be a neglected issue in the study of web ads. Web advertising is predominantly regarded as visual phenomena–commercial messages, as for instance banner ads that we watch, read, and eventually click on–but only rarely as something that we listen to. The present chapter presents...... an overview of the auditory dimensions in web advertising: Which kinds of sounds do we hear in web ads? What are the conditions and functions of sound in web ads? Moreover, the chapter proposes a theoretical framework in order to analyse the communicative functions of sound in web advertising. The main...... argument is that an understanding of the auditory dimensions in web advertising must include a reflection on the hypertextual settings of the web ad as well as a perspective on how users engage with web content....

  18. Sound Art Situations

    DEFF Research Database (Denmark)

    Krogh Groth, Sanne; Samson, Kristine

    2017-01-01

    and combine theories from several fields. Aspects of sound art studies, performance studies and contemporary art studies are presented in order to theoretically explore the very diverse dimensions of the two sound art pieces: Visual, auditory, performative, social, spatial and durational dimensions become......This article is an analysis of two sound art performances that took place June 2015 in outdoor public spaces in the social housing area Urbanplanen in Copenhagen, Denmark. The two performances were On the production of a poor acoustics by Brandon LaBelle and Green Interactive Biofeedback...... Environments (GIBE) by Jeremy Woodruff. In order to investigate the complex situation that arises when sound art is staged in such contexts, the authors of this article suggest exploring the events through approaching them as ‘situations’ (Doherty 2009). With this approach it becomes possible to engage...

  19. Sound as Popular Culture

    DEFF Research Database (Denmark)

    The wide-ranging texts in this book take as their premise the idea that sound is a subject through which popular culture can be analyzed in an innovative way. From an infant’s gurgles over a baby monitor to the roar of the crowd in a stadium to the sub-bass frequencies produced by sound systems...... in the disco era, sound—not necessarily aestheticized as music—is inextricably part of the many domains of popular culture. Expanding the view taken by many scholars of cultural studies, the contributors consider cultural practices concerning sound not merely as semiotic or signifying processes but as material......, physical, perceptual, and sensory processes that integrate a multitude of cultural traditions and forms of knowledge. The chapters discuss conceptual issues as well as terminologies and research methods; analyze historical and contemporary case studies of listening in various sound cultures; and consider...

  20. It sounds good!

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Both the atmosphere and we ourselves are hit by hundreds of particles every second and yet nobody has ever heard a sound coming from these processes. Like cosmic rays, particles interacting inside the detectors at the LHC do not make any noise…unless you've decided to use the ‘sonification’ technique, in which case you might even hear the Higgs boson sound like music. Screenshot of the first page of the "LHC sound" site. A group of particle physicists, composers, software developers and artists recently got involved in the ‘LHC sound’ project to make the particles at the LHC produce music. Yes…music! The ‘sonification’ technique converts data into sound. “In this way, if you implement the right software you can get really nice music out of the particle tracks”, says Lily Asquith, a member of the ATLAS collaboration and one of the initiators of the project. The ‘LHC...

  1. First and second sound of a unitary Fermi gas in highly oblate harmonic traps

    International Nuclear Information System (INIS)

    Hu, Hui; Dyke, Paul; Vale, Chris J; Liu, Xia-Ji

    2014-01-01

    We theoretically investigate first and second sound modes of a unitary Fermi gas trapped in a highly oblate harmonic trap at finite temperatures. Following the idea by Stringari and co-workers (2010 Phys. Rev. Lett. 105 150402), we argue that these modes can be described by the simplified two-dimensional two-fluid hydrodynamic equations. Two possible schemes—sound wave propagation and breathing mode excitation—are considered. We calculate the sound wave velocities and discretized sound mode frequencies, as a function of temperature. We find that in both schemes, the coupling between first and second sound modes is large enough to induce significant density fluctuations, suggesting that second sound can be directly observed by measuring in situ density profiles. The frequency of the second sound breathing mode is found to be highly sensitive to the superfluid density. (paper)

  2. Properties of sound attenuation around a two-dimensional underwater vehicle with a large cavitation number

    International Nuclear Information System (INIS)

    Ye Peng-Cheng; Pan Guang

    2015-01-01

    Due to the high speed of underwater vehicles, cavitation is generated inevitably along with the sound attenuation when the sound signal traverses through the cavity region around the underwater vehicle. The linear wave propagation is studied to obtain the influence of bubbly liquid on the acoustic wave propagation in the cavity region. The sound attenuation coefficient and the sound speed formula of the bubbly liquid are presented. Based on the sound attenuation coefficients with various vapor volume fractions, the attenuation of sound intensity is calculated under large cavitation number conditions. The result shows that the sound intensity attenuation is fairly small in a certain condition. Consequently, the intensity attenuation can be neglected in engineering. (paper)

  3. Nonlinear effects in the propagation of shortwave transverse sound in pure superconductors

    International Nuclear Information System (INIS)

    Gal'perin, Y.

    1982-01-01

    Various mechanisms are analyzed which lead to nonlinear phenomena (e.g., the dependence of the absorption coefficient and of the velocity of sound on its intensity) in the propagation of transverse shortwave sound in pure superconductors (the wavelength of the sound being much less than the mean free path of the quasiparticles). It is shown that the basic mechanism, over a wide range of superconductor parameters and of the sound intensity, is the so-called momentum nonlinearity. The latter is due to the distortion (induced by the sound wave) of the quasimomentum distribution of resonant electrons interacting with the wave. The dependences of the absorption coefficient and of the sound velocity on its intensity and on the temperature are analyzed in the vicinity of the superconducting transition point. The feasibility of an experimental study of nonlinear acoustic phenomena in the case of transverse sound is considered

  4. A Two-Level Sound Classification Platform for Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Stelios A. Mitilineos

    2018-01-01

    Full Text Available STORM is an ongoing European research project that aims at developing an integrated platform for monitoring, protecting, and managing cultural heritage sites through technical and organizational innovation. Part of the scheduled preventive actions for the protection of cultural heritage is the development of wireless acoustic sensor networks (WASNs that will be used for assessing the impact of human-generated activities as well as for monitoring potentially hazardous environmental phenomena. Collected sound samples will be forwarded to a central server where they will be automatically classified in a hierarchical manner; anthropogenic and environmental activity will be monitored, and stakeholders will be alarmed in the case of potential malevolent behavior or natural phenomena like excess rainfall, fire, gale, high tides, and waves. Herein, we present an integrated platform that includes sound sample denoising using wavelets, feature extraction from sound samples, Gaussian mixture modeling of these features, and a powerful two-layer neural network for automatic classification. We contribute to previous work by extending the proposed classification platform to perform low-level classification too, i.e., classify sounds to further subclasses that include airplane, car, and pistol sounds for the anthropogenic sound class; bird, dog, and snake sounds for the biophysical sound class; and fire, waterfall, and gale for the geophysical sound class. Classification results exhibit outstanding classification accuracy in both high-level and low-level classification thus demonstrating the feasibility of the proposed approach.

  5. Relating Cortical Wave Dynamics to Learning and Remembering

    Directory of Open Access Journals (Sweden)

    Eduardo Mercado III

    2014-12-01

    Full Text Available Electrical waves propagate across sensory and motor cortices in stereotypical patterns. These waves have been described as potentially facilitating sensory processing when they travel through sensory cortex, as guiding movement preparation and performance when they travel across motor cortex, and as possibly promoting synaptic plasticity and the consolidation of memory traces, especially during sleep. Here, an alternative theoretical framework is suggested that integrates Pavlovian hypotheses about learning and cortical function with concepts from contemporary proceduralist theories of memory. The proposed framework postulates that sensory-evoked cortical waves are gradually modified across repeated experiences such that the waves more effectively differentiate sensory events, and so that the waves are more likely to reverberate. It is argued that the qualities of cortical waves—their origins, form, intensity, speed, periodicity, extent, and trajectories —are a function of both the structural organization of neural circuits and ongoing reverberations resulting from previously experienced events. It is hypothesized that experience-dependent cortical plasticity, both in the short- and long-term, modulates the qualities of cortical waves, thereby enabling individuals to make progressively more precise distinctions between complex sensory events, and to reconstruct components of previously experienced events. Unlike most current neurobiological theories of learning and memory mechanisms, this hypothesis does not assume that synaptic plasticity, or any other form of neural plasticity, serves to store physical records of previously experienced events for later reactivation. Rather, the reorganization of cortical circuits may alter the potential for certain wave patterns to arise and persist. Understanding what factors determine the spatiotemporal dynamics of cortical waves, how structural changes affect their qualities, and how wave dynamics

  6. The Sounds of the Little and Big Bangs

    Directory of Open Access Journals (Sweden)

    Edward Shuryak

    2017-11-01

    Full Text Available Studies on heavy ion collisions have discovered that tiny fireballs of a new phase of matter—quark gluon plasma (QGP—undergo an explosion, called the Little Bang. In spite of its small size, not only is it well described by hydrodynamics, but even small perturbations on top of the explosion turned out to be well described by hydrodynamical sound modes. The cosmological Big Bang also went through phase transitions, related with Quantum Chromodynamics (QCD and electroweak/Higgs symmetry breaking, which are also expected to produce sounds. We discuss their subsequent evolution and hypothetical inverse acoustic cascade, amplifying the amplitude. Ultimately, the collision of two sound waves leads to the formation of one gravity waves. We briefly discuss how these gravity waves can be detected.

  7. Parallel-plate third sound waveguides with fixed and variable plate spacings for the study of fifth sound in superfluid helium

    International Nuclear Information System (INIS)

    Jelatis, G.J.

    1983-01-01

    Third sound in superfluid helium four films has been investigated using two parallel-plate waveguides. These investigations led to the observation of fifth sound, a new mode of sound propagation. Both waveguides consisted of two parallel pieces of vitreous quartz. The sound speed was obtained by measuring the time-of-flight of pulsed third sound over a known distance. Investigations from 1.0-1.7K were possible with the use of superconducting bolometers, which measure the temperature component of the third sound wave. Observations were initially made with a waveguide having a plate separation fixed at five microns. Adiabatic third sound was measured in the geometry. Isothermal third sound was also observed, using the usual, single-substrate technique. Fifth sound speeds, calculated from the two-fluid theory of helium and the speeds of the two forms of third sound, agreed in size and temperature dependence with theoretical predictions. Nevertheless, only equivocal observations of fifth sound were made. As a result, the film-substrate interaction was examined, and estimates of the Kapitza conductance were made. Assuming the dominance of the effects of this conductance over those due to the ECEs led to a new expression for fifth sound. A reanalysis of the initial data was made, which contained no adjustable parameters. The observation of fifth sound was seen to be consistent with the existence of an anomalously low boundary conductance

  8. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    Science.gov (United States)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was

  9. Generation of sound zones in 2.5 dimensions

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Olsen, Martin; Møller, Martin

    2011-01-01

    in a certain direction within a certain region of a room and at the same time suppress sound in another region. The method is examined through simulations and experiments. For comparison a simpler method based on the idea of maximising the ratio of the potential acoustic energy in an ensonified zone......Amethod for generating sound zones with different acoustic properties in a room is presented. The method is an extension of the two-dimensional multi-zone sound field synthesis technique recently developed by Wu and Abhayapala; the goal is, for example, to generate a plane wave that propagates...... to the potential acoustic energy in a quiet zone is also examined....

  10. Chatter, reverberation, and the static in the system: Noise in American cinema culture

    Science.gov (United States)

    Ward, Meredith C.

    Noise is unwelcome in film culture; it has long been associated with disruption, counter-productivity, and discord. Yet taking a historical approach to noise and connecting its various manifestations to American auditory culture at large reveals noise to be a historiographically productive category for study. Approaching noise through its effects on four areas of American cinema culture---the social, technological, acoustical, and aesthetic---in four key historical moments, this dissertation demonstrates that listening to noise can explain conflicts in the history of film sound and audiences. Examples include silencing the social noise of rowdy spectators during the nickelodeon period; the Academy of Motion Picture Arts and Science's attempt to compete with Bell Laboratories with technological, noise-based research during film's transition to sound; the rise of acoustical design in film theaters to quash noise and produce contemplative listening in film spectators; and the user's current navigation of her attention between the sounds of media and urban life while viewing films on smartphones. In each case, the presence of noise has produced tensions that reveal the power structure of film culture. Terming sound "noise" is an act of judgment that has social ramifications, and the struggle against noise is also a struggle between groups vying for power within cinema culture: conflict over who may determine whose sound is "noise"; competition between industries regarding who owns sound knowledge; debates about which sounds are "noise" and which are legitimate components of the cinema experience; and tensions between our established expectations of noisy public space and the ways in which we create quiet spheres via mobile listening. Looking to the aural historical dialogues in which cinema culture partook, this project outlines the conditions of possibility within which listening to the cinema emerged in these periods. Understanding these historical contexts, we can

  11. Limitations on the upconversion of ion sound to Langmuir turbulence

    Science.gov (United States)

    Vlahos, L.; Papadopoulos, K.

    1982-01-01

    The weak turbulence theory of Tsytovich, Stenflo and Wilhelmsson (1981) for evaluation of the nonlinear transfer of ion acoustic waves to Langmuir waves is shown to be limited in its region of validity to the level of ion acoustic waves. It is also demonstrated that, in applying the upconversion of ion sound to Langmuir waves for electron acceleration, nonlinear scattering should be self-consistently included, with a suppression of the upconversion process resulting. The impossibility of accelerating electrons by such a process for any reasonable physical system is thereby reaffirmed.

  12. Regularization in global sound equalization based on effort variation

    DEFF Research Database (Denmark)

    Stefanakis, Nick; Sarris, John; Jacobsen, Finn

    2009-01-01

    . Effort variation equalization involves modifying the conventional cost function in sound equalization, which is based on minimizing least-squares reproduction errors, by adding a term that is proportional to the squared deviations between complex source strengths, calculated independently for the sources......Sound equalization in closed spaces can be significantly improved by generating propagating waves that are naturally associated with the geometry, as, for example, plane waves in rectangular enclosures. This paper presents a control approach termed effort variation regularization based on this idea...

  13. Ion-sound emission by Langmuir soliton reflected at density barrier

    International Nuclear Information System (INIS)

    El-Ashry, M.Y.

    1989-07-01

    The emission of ion-sound waves by an accelerated Langmuir soliton is studied. The acceleration of the soliton is due to an inhomogeneous density barrier. On the assumption that the kinetic energy of the Langmuir soliton is smaller than the potential energy created by the barrier. The basic equations describing the dynamic behaviour of the soliton and the emission of the ion-sound waves are formulated. The qualitative spatial distributions of the perturbed concentration in the ion-sound waves are analyzed at different characteristic points of the soliton. The energy lost by the soliton, as a result of the emission, is estimated. (author). 6 refs, 4 figs

  14. Integrated sound absorption in thermally activated concrete ceilings - acoustic and thermal effectiveness of sound-absorber strips spaced at intervals; Integrierte Schallabsorption in thermisch aktivierten Betondecken - akustische und thermische Wirksamkeit periodischer Schallabsorberstreifen

    Energy Technology Data Exchange (ETDEWEB)

    Drotleff, Horst; Wack, Roman; Leistner, Philip; Holm, Andreas; Ziegler, Matthias; Sedlbauer, Klaus [Fraunhofer-Institut fuer Bauphysik IBP, Stuttgart (Germany)

    2011-10-15

    From the perspectives of energy as well as indoor climate, thermally activated concrete ceilings make sense. Used in office buildings, however, their drawback becomes apparent: they are acoustically reflective. The conventional approaches use sound-absorbing suspended sails and absorber baffles or heat-conducting sound absorbers embedded in large areas of the concrete. In this paper, an alternative approach is presented and is evaluated acoustically and thermally. A few strips of sound absorber, arranged at intervals, are mounted flush into the concrete ceiling. To calculate the sound-absorption spectrum, an already widely publicised model (the Rayleigh approach) is used. It predicts the sound-absorption spectrum for normal sound incidence very well. For diffuse sound incidence, the difference to reverberation chamber measurements is greater, presumably because of the edge effect. The sound- absorption coefficient of the design can be tuned by skilful choice of the strip geometry, and it is significantly higher than the expected average value for the surface. On the one hand, the thermal efficiency of the components is determined by comparing the heat fluxes in the ceilings with absorber strips to an untreated reference ceiling. On the other hand, the indoor climate is investigated using a room model for office rooms of both solid and lightweight constructions. The influence of the strips (proportion of absorber area 20 %) on the thermal efficiency and indoor climate is low. Two absorber materials are examined in the strip approach: open-cell foam glass and a micro-perforated metallic absorber. While the metallic absorber displays thermal advantages, its sound absorption spectrum - even at high surface-coverage proportions - exhibits a much lower absorption coefficient than, for example, open-cell foam glass strips with only 20 % ceiling coverage. A demonstration in situ shows the potential of the absorber strips spaced at intervals. However, the method chosen in

  15. Accretion Disk Reverberation with Hubble Space Telescope Observations of NGC 4593: Evidence for Diffuse Continuum Lags

    Science.gov (United States)

    Cackett, Edward M.; Chiang, Chia-Ying; McHardy, Ian; Edelson, Rick; Goad, Michael R.; Horne, Keith; Korista, Kirk T.

    2018-04-01

    The Seyfert 1 galaxy NGC 4593 was monitored spectroscopically with the Hubble Space Telescope as part of a reverberation mapping campaign that also included Swift, Kepler, and ground-based photometric monitoring. During 2016 July 12–August 6, we obtained 26 spectra across a nearly continuous wavelength range of ∼1150–10000 Å. These were combined with Swift data to produce a UV/optical “lag spectrum,” which shows the interband lag relative to the Swift UVW2 band as a function of wavelength. The broad shape of the lag spectrum appears to follow the τ ∝ λ 4/3 relation seen previously in photometric interband lag measurements of other active galactic nuclei (AGNs). This shape is consistent with the standard thin disk model, but the magnitude of the lags implies a disk that is a factor of ∼3 larger than predicted, again consistent with what has been previously seen in other AGNs. In all cases these large disk sizes, which are also implied by independent gravitational microlensing of higher-mass AGNs, cannot be simply reconciled with the standard model. However, the most striking feature in this higher-resolution lag spectrum is a clear excess around the 3646 Å Balmer jump. This strongly suggests that diffuse emission from gas in the much larger broad-line region (BLR) must also contribute significantly to the interband lags. While the relative contributions of the disk and BLR cannot be uniquely determined in these initial measurements, it is clear that both will need to be considered to comprehensively model and understand AGN lag spectra.

  16. Reverberation Mapping of the Kepler-Field AGN KA1858+4850

    Science.gov (United States)

    Pei, Liuyi; Barth, Aaron J.; Aldering, Greg S.; Briley, Michael M.; Carroll, Carla J.; Carson, Daniel J.; Cenko, S., Bradley; Clubb, Kelsey I.; Cohen, Daniel P.; Cucchiara, Antonino; hide

    2014-01-01

    KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3-m telescope from February to November of 2012, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hbeta light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method, and found rest-frame lags of tCCF = 13.53+2.03 -2.32 days and tJAVELIN = 13.15+1.08 -1.00 days. The Hbeta root-mean-square line profile has a width of sigma line = 770 +/- 49 km s(exp -1). Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M(sub BH) = 8.06+1.59 -1.72 ×10(exp 6) solar mass for the mass of the central black hole and an Eddington ratio of L/L(sub Edd) (is) approx. 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei.

  17. Reverberation Mapping of the KEPLER Field AGN KA1858+4850

    Science.gov (United States)

    Pei, Liuyi; Barth, Aaron J.; Aldering, Greg S.; Briley, Michael M.; Carroll, Carla J.; Carson, Daniel J.; Cenko, S. Bradley; Clubb, Kelsey I.; Cohen, Daniel P.; Cucchiara, Antonino; Desjardins, Tyler D.; Edelson, Rick; Fang, Jerome J.; Fedrow, Joseph M.; Filippenko, Alexei V.; Fox, Ori D.; Furniss, Amy; Gates, Elinor L.; Gregg, Michael; Gustafson, Scott; Horst, J. Chuck; Joner, Michael D.; Kelly, Patrick L.; Lacy, Mark; Laney, C. David; Leonard, Douglas C.; Li, Weidong; Malkan, Matthew A.; Margon, Bruce; Neeleman, Marcel; Nguyen, My L.; Prochaska, J. Xavier; Ross, Nathaniel R.; Sand, David J.; Searcy, Kinchen J.; Shivvers, Isaac S.; Silverman, Jeffrey M.; Smith, Graeme H.; Suzuki, Nao; Smith, Krista Lynne; Tytler, David; Werk, Jessica K.; Worseck, Gábor

    2014-11-01

    KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3 m telescope from 2012 February to November, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hβ light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method and found rest-frame lags of τ CCF = 13.53+2.03-2.32 days and τ JAVELIN = 13.15+1.08-1.00 days. The Hβ rms line profile has a width of σline = 770 ± 49 km s-1. Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M{BH} = 8.06+1.59-1.72 × 106 {M}⊙ for the mass of the central black hole and an Eddington ratio of L/L Edd ≈ 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei.

  18. Reverberation mapping of the Kepler field AGN KA1858+4850

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Liuyi; Barth, Aaron J.; Carson, Daniel J. [Department of Physics and Astronomy, University of California, Irvine, CA, 92697 (United States); Aldering, Greg S.; Cucchiara, Antonino [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Briley, Michael M. [Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608 (United States); Carroll, Carla J. [Department of Physics and Astronomy, N283 ESC, Brigham Young University, Provo, UT 84602 (United States); Cenko, S. Bradley; Edelson, Rick [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Clubb, Kelsey I.; Cohen, Daniel P.; Filippenko, Alexei V.; Fox, Ori D. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Desjardins, Tyler D. [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Fang, Jerome J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Fedrow, Joseph M. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Furniss, Amy [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mt. Hamilton, CA 95140 (United States); Gregg, Michael [Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Gustafson, Scott [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); and others

    2014-11-01

    KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3 m telescope from 2012 February to November, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hβ light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method and found rest-frame lags of τ{sub CCF}=13.53{sub −2.32}{sup +2.03} days and τ {sub JAVELIN} =13.15{sub −1.00}{sup +1.08} days. The Hβ rms line profile has a width of σ{sub line} = 770 ± 49 km s{sup –1}. Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M{sub BH}=8.06{sub −1.72}{sup +1.59}×10{sup 6}M{sub ⊙} for the mass of the central black hole and an Eddington ratio of L/L {sub Edd} ≈ 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei.

  19. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: RAPID C iv BROAD ABSORPTION LINE VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Brandt, W. N.; Trump, J. R.; Schneider, D. P. [Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 (Canada); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Vivek, M.; Dawson, K. S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Ak, N. Filiz [Faculty of Sciences, Department of Astronomy and Space Sciences, Erciyes University, 38039 Kayseri (Turkey); Chen, Yuguang [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Denney, K. D.; Kochanek, C. S.; Peterson, B. M. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Green, Paul J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Jiang, Linhua [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); McGreer, Ian D. [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Pâris, I. [INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste (Italy); Tao, Charling [Centre de Physique des Particules de Marseille, Aix-Marseille Universite, CNRS /IN2P3, 163, avenue de Luminy, Case 902, F-13288 Marseille Cedex 09 (France); Wood-Vasey, W. M. [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States); Bizyaev, Dmitry, E-mail: grier@psu.edu [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States); and others

    2015-06-10

    We report the discovery of rapid variations of a high-velocity C iv broad absorption line trough in the quasar SDSS J141007.74+541203.3. This object was intensively observed in 2014 as a part of the Sloan Digital Sky Survey Reverberation Mapping Project, during which 32 epochs of spectroscopy were obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We observe significant (>4σ) variability in the equivalent width (EW) of the broad (∼4000 km s{sup −1} wide) C iv trough on rest-frame timescales as short as 1.20 days (∼29 hr), the shortest broad absorption line variability timescale yet reported. The EW varied by ∼10% on these short timescales, and by about a factor of two over the duration of the campaign. We evaluate several potential causes of the variability, concluding that the most likely cause is a rapid response to changes in the incident ionizing continuum. If the outflow is at a radius where the recombination rate is higher than the ionization rate, the timescale of variability places a lower limit on the density of the absorbing gas of n{sub e} ≳ 3.9 × 10{sup 5} cm{sup −3}. The broad absorption line variability characteristics of this quasar are consistent with those observed in previous studies of quasars, indicating that such short-term variability may in fact be common and thus can be used to learn about outflow characteristics and contributions to quasar/host-galaxy feedback scenarios.

  20. Sound & The Society

    DEFF Research Database (Denmark)

    Schulze, Holger

    2014-01-01

    How are those sounds you hear right now socially constructed and evaluated, how are they architecturally conceptualized and how dependant on urban planning, industrial developments and political decisions are they really? How is your ability to hear intertwined with social interactions and their ...... and their professional design? And how is listening and sounding a deeply social activity – constructing our way of living together in cities as well as in apartment houses? A radio feature with Nina Backmann, Jochen Bonz, Stefan Krebs, Esther Schelander & Holger Schulze......How are those sounds you hear right now socially constructed and evaluated, how are they architecturally conceptualized and how dependant on urban planning, industrial developments and political decisions are they really? How is your ability to hear intertwined with social interactions...

  1. Urban Sound Interfaces

    DEFF Research Database (Denmark)

    Breinbjerg, Morten

    2012-01-01

    This paper draws on the theories of Michel de Certeau and Gaston Bachelard to discuss how media architecture, in the form of urban sound interfaces, can help us perceive the complexity of the spaces we inhabit, by exploring the history and the narratives of the places in which we live. In this pa......This paper draws on the theories of Michel de Certeau and Gaston Bachelard to discuss how media architecture, in the form of urban sound interfaces, can help us perceive the complexity of the spaces we inhabit, by exploring the history and the narratives of the places in which we live....... In this paper, three sound works are discussed in relation to the iPod, which is considered as a more private way to explore urban environments, and as a way to control the individual perception of urban spaces....

  2. Predicting outdoor sound

    CERN Document Server

    Attenborough, Keith; Horoshenkov, Kirill

    2014-01-01

    1. Introduction  2. The Propagation of Sound Near Ground Surfaces in a Homogeneous Medium  3. Predicting the Acoustical Properties of Outdoor Ground Surfaces  4. Measurements of the Acoustical Properties of Ground Surfaces and Comparisons with Models  5. Predicting Effects of Source Characteristics on Outdoor Sound  6. Predictions, Approximations and Empirical Results for Ground Effect Excluding Meteorological Effects  7. Influence of Source Motion on Ground Effect and Diffraction  8. Predicting Effects of Mixed Impedance Ground  9. Predicting the Performance of Outdoor Noise Barriers  10. Predicting Effects of Vegetation, Trees and Turbulence  11. Analytical Approximations including Ground Effect, Refraction and Turbulence  12. Prediction Schemes  13. Predicting Sound in an Urban Environment.

  3. Understanding "Human" Waves: Exploiting the Physics in a Viral Video

    Science.gov (United States)

    Ferrer-Roca, Chantal

    2018-01-01

    Waves are a relevant part of physics that students find difficult to grasp, even in those cases in which wave propagation kinematics can be visualized. This may hinder a proper understanding of sound, light or quantum physics phenomena that are explained using a wave model. So-called "human" waves, choreographed by people, have proved to…

  4. Experimental methodology for obtaining sound absorption coefficients

    Directory of Open Access Journals (Sweden)

    Carlos A. Macía M

    2011-07-01

    Full Text Available Objective: the authors propose a new methodology for estimating sound absorption coefficients using genetic algorithms. Methodology: sound waves are generated and conducted along a rectangular silencer. The waves are then attenuated by the absorbing material covering the silencer’s walls. The attenuated sound pressure level is used in a genetic algorithm-based search to find the parameters of the proposed attenuation expressions that include geometric factors, the wavelength and the absorption coefficient. Results: a variety of adjusted mathematical models were found that make it possible to estimate the absorption coefficients based on the characteristics of a rectangular silencer used for measuring the attenuation of the noise that passes through it. Conclusions: this methodology makes it possible to obtain the absorption coefficients of new materials in a cheap and simple manner. Although these coefficients might be slightly different from those obtained through other methodologies, they provide solutions within the engineering accuracy ranges that are used for designing noise control systems.

  5. Numerical Estimation of Sound Transmission Loss in Launch Vehicle Payload Fairing

    Science.gov (United States)

    Chandana, Pawan Kumar; Tiwari, Shashi Bhushan; Vukkadala, Kishore Nath

    2017-08-01

    Coupled acoustic-structural analysis of a typical launch vehicle composite payload faring is carried out, and results are validated with experimental data. Depending on the frequency range of interest, prediction of vibro-acoustic behavior of a structure is usually done using the finite element method, boundary element method or through statistical energy analysis. The present study focuses on low frequency dynamic behavior of a composite payload fairing structure using both coupled and uncoupled vibro-acoustic finite element models up to 710 Hz. A vibro-acoustic model, characterizing the interaction between the fairing structure, air cavity, and satellite, is developed. The external sound pressure levels specified for the payload fairing's acoustic test are considered as external loads for the analysis. Analysis methodology is validated by comparing the interior noise levels with those obtained from full scale Acoustic tests conducted in a reverberation chamber. The present approach has application in the design and optimization of acoustic control mechanisms at lower frequencies.

  6. Prediction of sound transmission loss through multilayered panels by using Gaussian distribution of directional incident energy

    Science.gov (United States)

    Kang; Ih; Kim; Kim

    2000-03-01

    In this study, a new prediction method is suggested for sound transmission loss (STL) of multilayered panels of infinite extent. Conventional methods such as random or field incidence approach often given significant discrepancies in predicting STL of multilayered panels when compared with the experiments. In this paper, appropriate directional distributions of incident energy to predict the STL of multilayered panels are proposed. In order to find a weighting function to represent the directional distribution of incident energy on the wall in a reverberation chamber, numerical simulations by using a ray-tracing technique are carried out. Simulation results reveal that the directional distribution can be approximately expressed by the Gaussian distribution function in terms of the angle of incidence. The Gaussian function is applied to predict the STL of various multilayered panel configurations as well as single panels. The compared results between the measurement and the prediction show good agreements, which validate the proposed Gaussian function approach.

  7. A virtual auditory environment for investigating the auditory signal processing of realistic sounds

    DEFF Research Database (Denmark)

    Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2008-01-01

    In the present study, a novel multichannel loudspeaker-based virtual auditory environment (VAE) is introduced. The VAE aims at providing a versatile research environment for investigating the auditory signal processing in real environments, i.e., considering multiple sound sources and room...... reverberation. The environment is based on the ODEON room acoustic simulation software to render the acoustical scene. ODEON outputs are processed using a combination of different order Ambisonic techniques to calculate multichannel room impulse responses (mRIR). Auralization is then obtained by the convolution...... the VAE development, special care was taken in order to achieve a realistic auditory percept and to avoid “artifacts” such as unnatural coloration. The performance of the VAE has been evaluated and optimized on a 29 loudspeaker setup using both objective and subjective measurement techniques....

  8. [High-frequency components of occlusal sound in sliding movement].

    Science.gov (United States)

    Nagai, K

    1990-03-01

    We postulated that high-frequency components of the occlusal sound occurring due to the characteristic vibration of teeth can be useful data for confirmation of the stability in occlusion, and studied the high-frequency components in the cases both of an experimental sliding movement and a normal occlusion. The results obtained were as follows. 1. A study on high-frequency components of the occlusal sound in an experimental sliding movement. 1) A study on wave type of the occlusal sound revealed one damped oscillation in an impact form and two in a slide form. 2) Spectrum analysis of the damped oscillation showed a similar spectrum pattern with a peak existing between 16KHz or more and 17KHz or less in both impact and slide cases. 2. A study on high-frequency components of the occlusal sound in a normal occlusion case. 1) The wave type in occlusal sound we have observed in a normal occlusion group and in a prosthetic or operative group was as follows: One damped oscillation shown in an impact form and two damped oscillation in a slide form which were the same as those shown in the case where an interference device was attached. 2) Duration of the sliding movement was short in a normal occlusion group, but was prolonged in a prosthetic or operative group. 3) The incidence of the wave type in occlusal sound was 56.7% in a prosthetic or operative group as compared to 87.8% in a normal occlusion group in an impact form. In contrast, the incidence was 43.3% in a prosthetic or operative group as compared to 12.2% in a normal occlusion group in a slide form. Such difference in the incidence between the wave types suggested that high-frequency components of occlusal sound can be an index for judgement of the stability in occlusion.

  9. Stress wave focusing transducers

    Energy Technology Data Exchange (ETDEWEB)

    Visuri, S.R., LLNL

    1998-05-15

    Conversion of laser radiation to mechanical energy is the fundamental process behind many medical laser procedures, particularly those involving tissue destruction and removal. Stress waves can be generated with laser radiation in several ways: creation of a plasma and subsequent launch of a shock wave, thermoelastic expansion of the target tissue, vapor bubble collapse, and ablation recoil. Thermoelastic generation of stress waves generally requires short laser pulse durations and high energy density. Thermoelastic stress waves can be formed when the laser pulse duration is shorter than the acoustic transit time of the material: {tau}{sub c} = d/c{sub s} where d = absorption depth or spot diameter, whichever is smaller, and c{sub s} = sound speed in the material. The stress wave due to thermoelastic expansion travels at the sound speed (approximately 1500 m/s in tissue) and leaves the site of irradiation well before subsequent thermal events can be initiated. These stress waves, often evolving into shock waves, can be used to disrupt tissue. Shock waves are used in ophthalmology to perform intraocular microsurgery and photodisruptive procedures as well as in lithotripsy to fragment stones. We have explored a variety of transducers that can efficiently convert optical to mechanical energy. One such class of transducers allows a shock wave to be focused within a material such that the stress magnitude can be greatly increased compared to conventional geometries. Some transducer tips could be made to operate regardless of the absorption properties of the ambient media. The size and nature of the devices enable easy delivery, potentially minimally-invasive procedures, and precise tissue- targeting while limiting thermal loading. The transducer tips may have applications in lithotripsy, ophthalmology, drug delivery, and cardiology.

  10. Blinded Comparison between an In-Air Reverberation Method and an Electronic Probe Tester in the Detection of Ultrasound Probe Faults.

    Science.gov (United States)

    Dudley, Nicholas J; Woolley, Darren J

    2017-12-01

    The aim of this study was to perform a blinded trial, comparing the results of a visual inspection of the in-air reverberation pattern with the results of an electronic probe tester in detecting ultrasound probe faults. Sixty-two probes were tested. A total of 28 faults were found, 3 only by in-air reverberation assessment and 2 only by the electronic probe tester. The electronic probe tester provided additional information regarding the location of the fault in 74% of the cases in which both methods detected a fault. It is possible to detect the majority of probe faults by visual inspection and in-air reverberation assessment. The latter provides an excellent first-line test, easily performed on a daily basis by equipment users. An electronic probe tester is required if detailed evaluation of faults is necessary. Copyright © 2017 World Federation for Ultrasound in Medicine and Biology. All rights reserved.

  11. Sound & The Senses

    DEFF Research Database (Denmark)

    Schulze, Holger

    2012-01-01

    How are those sounds you hear right now technically generated and post-produced, how are they aesthetically conceptualized and how culturally dependant are they really? How is your ability to hear intertwined with all the other senses and their cultural, biographical and technological constructio...... over time? And how is listening and sounding a deeply social activity – constructing our way of living together in cities as well as in apartment houses? A radio feature with Jonathan Sterne, AGF a.k.a Antye Greie, Jens Gerrit Papenburg & Holger Schulze....

  12. Sound for digital video

    CERN Document Server

    Holman, Tomlinson

    2013-01-01

    Achieve professional quality sound on a limited budget! Harness all new, Hollywood style audio techniques to bring your independent film and video productions to the next level.In Sound for Digital Video, Second Edition industry experts Tomlinson Holman and Arthur Baum give you the tools and knowledge to apply recent advances in audio capture, video recording, editing workflow, and mixing to your own film or video with stunning results. This fresh edition is chockfull of techniques, tricks, and workflow secrets that you can apply to your own projects from preproduction

  13. Beacons of Sound

    DEFF Research Database (Denmark)

    Knakkergaard, Martin

    2018-01-01

    The chapter discusses expectations and imaginations vis-à-vis the concert hall of the twenty-first century. It outlines some of the central historical implications of western culture’s haven for sounding music. Based on the author’s study of the Icelandic concert-house Harpa, the chapter considers...... how these implications, together with the prime mover’s visions, have been transformed as private investors and politicians took over. The chapter furthermore investigates the objectives regarding musical sound and the far-reaching demands concerning acoustics that modern concert halls are required...

  14. Neuroplasticity beyond sounds

    DEFF Research Database (Denmark)

    Reybrouck, Mark; Brattico, Elvira

    2015-01-01

    Capitalizing from neuroscience knowledge on how individuals are affected by the sound environment, we propose to adopt a cybernetic and ecological point of view on the musical aesthetic experience, which includes subprocesses, such as feature extraction and integration, early affective reactions...... and motor actions, style mastering and conceptualization, emotion and proprioception, evaluation and preference. In this perspective, the role of the listener/composer/performer is seen as that of an active "agent" coping in highly individual ways with the sounds. The findings concerning the neural...

  15. Eliciting Sound Memories.

    Science.gov (United States)

    Harris, Anna

    2015-11-01

    Sensory experiences are often considered triggers of memory, most famously a little French cake dipped in lime blossom tea. Sense memory can also be evoked in public history research through techniques of elicitation. In this article I reflect on different social science methods for eliciting sound memories such as the use of sonic prompts, emplaced interviewing, and sound walks. I include examples from my research on medical listening. The article considers the relevance of this work for the conduct of oral histories, arguing that such methods "break the frame," allowing room for collaborative research connections and insights into the otherwise unarticulatable.

  16. SoleSound

    DEFF Research Database (Denmark)

    Zanotto, Damiano; Turchet, Luca; Boggs, Emily Marie

    2014-01-01

    This paper introduces the design of SoleSound, a wearable system designed to deliver ecological, audio-tactile, underfoot feedback. The device, which primarily targets clinical applications, uses an audio-tactile footstep synthesis engine informed by the readings of pressure and inertial sensors...... embedded in the footwear to integrate enhanced feedback modalities into the authors' previously developed instrumented footwear. The synthesis models currently implemented in the SoleSound simulate different ground surface interactions. Unlike similar devices, the system presented here is fully portable...

  17. The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei From Reverberation Mapping and Hubble Space Telescope Imaging

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.

    2009-01-01

    We investigate the relationship between black hole mass and bulge luminosity for active galactic nuclei (AGNs) with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope...... of the relationship for AGNs is 0.76-0.85 with an uncertainty of ~0.1, somewhat shallower than the M BH vprop L 1.0±0.1 relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This difference is somewhat perplexing, as the AGN black hole masses include an overall...

  18. The role of spectral detail in the binaural transfer function on perceived externalization in a reverberant environment

    DEFF Research Database (Denmark)

    Hassager, Henrik Gert; Gran, Fredrik; Dau, Torsten

    2016-01-01

    . For various filter bandwidths, the modified BRIRs were convolved with broadband noise and listeners judged the perceived position of the noise when virtualized over headphones. Only reductions in spectral details of the direct part obtained with filter bandwidths broader than one equivalent rectangular...... bandwidth affected externalization. Reductions in spectral details of the reverberant part had only little influence on externalization. In both conditions, externalization was not as pronounced at 0° as at 50°. To characterize the auditory processes that may be involved in the perception of externalization...

  19. Applying cybernetic technology to diagnose human pulmonary sounds.

    Science.gov (United States)

    Chen, Mei-Yung; Chou, Cheng-Han

    2014-06-01

    Chest auscultation is a crucial and efficient method for diagnosing lung disease; however, it is a subjective process that relies on physician experience and the ability to differentiate between various sound patterns. Because the physiological signals composed of heart sounds and pulmonary sounds (PSs) are greater than 120 Hz and the human ear is not sensitive to low frequencies, successfully making diagnostic classifications is difficult. To solve this problem, we constructed various PS recognition systems for classifying six PS classes: vesicular breath sounds, bronchial breath sounds, tracheal breath sounds, crackles, wheezes, and stridor sounds. First, we used a piezoelectric microphone and data acquisition card to acquire PS signals and perform signal preprocessing. A wavelet transform was used for feature extraction, and the PS signals were decomposed into frequency subbands. Using a statistical method, we extracted 17 features that were used as the input vectors of a neural network. We proposed a 2-stage classifier combined with a back-propagation (BP) neural network and learning vector quantization (LVQ) neural network, which improves classification accuracy by using a haploid neural network. The receiver operating characteristic (ROC) curve verifies the high performance level of the neural network. To expand traditional auscultation methods, we constructed various PS diagnostic systems that can correctly classify the six common PSs. The proposed device overcomes the lack of human sensitivity to low-frequency sounds and various PS waves, characteristic values, and a spectral analysis charts are provided to elucidate the design of the human-machine interface.

  20. Sound Symbolism in Basic Vocabulary

    Directory of Open Access Journals (Sweden)

    Søren Wichmann

    2010-04-01

    Full Text Available The relationship between meanings of words and their sound shapes is to a large extent arbitrary, but it is well known that languages exhibit sound symbolism effects violating arbitrariness. Evidence for sound symbolism is typically anecdotal, however. Here we present a systematic approach. Using a selection of basic vocabulary in nearly one half of the world’s languages we find commonalities among sound shapes for words referring to same concepts. These are interpreted as due to sound symbolism. Studying the effects of sound symbolism cross-linguistically is of key importance for the understanding of language evolution.