WorldWideScience

Sample records for vibromusic sound wave

  1. 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 ...

  2. REFLECTION OF ELECTROMAGNETIC WAVES FROM SOUND WAVES

    Science.gov (United States)

    The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave is discussed. By analogy with the...with the sound frequency. An experiment is described in which the Bragg reflection of 3 cm electromagnetic waves from a standing sound wave beneath a water surface is observed.

  3. Just How Does Sound Wave?

    Science.gov (United States)

    Shipman, Bob

    2006-01-01

    When children first hear the term "sound wave" perhaps they might associate it with the way a hand waves or perhaps the squiggly line image on a television monitor when sound recordings are being made. Research suggests that children tend to think sound somehow travels as a discrete package, a fast-moving invisible thing, and not something that…

  4. Sound Waves Levitate Substrates

    Science.gov (United States)

    Lee, M. C.; Wang, T. G.

    1982-01-01

    System recently tested uses acoustic waves to levitate liquid drops, millimeter-sized glass microballoons, and other objects for coating by vapor deposition or capillary attraction. Cylindrical contactless coating/handling facility employs a cylindrical acoustic focusing radiator and a tapered reflector to generate a specially-shaped standing wave pattern. Article to be processed is captured by the acoustic force field under the reflector and moves as reflector is moved to different work stations.

  5. Vortices and sound waves in superfluids

    OpenAIRE

    Lee, Kimyeong

    1994-01-01

    We consider the dynamics of vortex strings and sound waves in superfluids in the phenomenological Landau-Ginzburg equation. We first derive the vortex equation where the velocity of a vortex is determined by the average fluid velocity and the density gradient near the vortex. We then derive the effective action for vortex strings and sound waves by the dual formulation. The effective action might be useful in calculating the emission rate of sound waves by moving vortex strings.

  6. Waves and Sound, An Experiment that Walks.

    Science.gov (United States)

    Brunschwig, Fernand

    An experiment on sound waves, developed for non-science majors in a college physics course, is described. The student investigates the interference of two sound waves and measures and wavelength as he uses a prerecorded tape and a cassette player. The student is tutored by the cassette tape recorder, which also produces the overlapping sound…

  7. Fundamental plasma emission involving ion sound waves

    Science.gov (United States)

    Cairns, Iver H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L + or - S to 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.

  8. Snowflake Topological Insulator for Sound Waves

    OpenAIRE

    Brendel, Christian; Peano, Vittorio; Painter, Oskar; Marquardt, Florian

    2017-01-01

    We show how the snowflake phononic crystal structure, which has been realized experimentally recently, can be turned into a topological insulator for sound waves. This idea, based purely on simple geometrical modifications, could be readily implemented on the nanoscale.

  9. 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.

  10. Nonlinear wave interactions of kinetic sound waves

    Directory of Open Access Journals (Sweden)

    G. Brodin

    2015-08-01

    Full Text Available We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.

  11. Crova's Disc: A Way to Make Sound Waves "Visible."

    Science.gov (United States)

    Hastings, R. B.

    1981-01-01

    Explained are the differences between and offered are examples of longitudinal and transverse sound waves. Described is the construction of the Crova's Disc, a device used in the teaching of the propagation and properties of sound waves. (DS)

  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. 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...

  14. How to Use a Candle to Study Sound Waves

    Science.gov (United States)

    Carvalho, P. Simeão; Briosa, E.; Rodrigues, M.; Pereira, C.; Ataíde, M.

    2013-01-01

    It is well known that sound waves in air are longitudinal waves. Although teachers use analogies such as compressing horizontal springs to demonstrate what longitudinal waves look like, students still present some difficulty in understanding that (1) sound waves correspond to oscillations of air particles, and (2) there is no "air flow"…

  15. Standing Sound Waves in Air with DataStudio

    Science.gov (United States)

    Kraftmakher, Yaakov

    2010-01-01

    Two experiments related to standing sound waves in air are adapted for using the ScienceWorkshop data-acquisition system with the DataStudio software from PASCO scientific. First, the standing waves are created by reflection from a plane reflector. The distribution of the sound pressure along the standing wave is measured. Second, the resonance…

  16. Visualization of Sound Waves Using Regularly Spaced Soap Films

    Science.gov (United States)

    Elias, F.; Hutzler, S.; Ferreira, M. S.

    2007-01-01

    We describe a novel demonstration experiment for the visualization and measurement of standing sound waves in a tube. The tube is filled with equally spaced soap films whose thickness varies in response to the amplitude of the sound wave. The thickness variations are made visible based on optical interference. The distance between two antinodes is…

  17. [Pneumonia, when sound waves mix things up].

    Science.gov (United States)

    Wachters, C; Hildebrand, M

    2011-01-01

    A 29-year old man is admitted in our hospital for a dry cough which appeared a few weeks earlier and is now associated with a breath depending thoracic pain. As an engineer, he is realizing a thesis about the sound waves produced by coughing and is therefore frequently exposed to patients with various pulmonary infections. The chest X-ray, presents predominant pulmonary infiltrates on the periphery of the upper fields of the lungs. Blood analysis revealed a hypereosinophilia of 4.650/microl. The various bacteriological, parasitic and viral investigation tests are negative. The bronchioalveolar washing reveals more than 50% eosinophils. Exclusive pulmonary impairment and lack of autoantibody moved us to the diagnosis of chronic eosinophilic pneumonia (or Carrington syndrome). Corticosteroids were started at the dosis of 0,5 mg/kg of methyl-prednisolone. Clinical and biological features improved amazingly within 48 hours. This case report illustrates the overlap between the chronic eosinophilic pneumonia and the Churg-Strauss desease who can be considered as variants of the hypereosinophilic syndrome (HES). Therefore, the use of anti-interleukin-5 antibodies, already used in the SHE and Churg-Strauss syndrome, might be useful in this case.

  18. 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....

  19. Update on the Effects of Sound Wave on Plants

    Directory of Open Access Journals (Sweden)

    Md. Emran Khan Chowdhury

    2014-03-01

    Full Text Available Plant growth is considered the sum of cell proliferation and subsequent elongation of the cells. The continuous proliferation and elongation of plant cells are vital to the production of new organs, which have a significant impact on overall plant growth. Accordingly, the relationship between environmental stimuli, such as temperature, light, wind, and sound waves to plant growth is of great interest in studies of plant development. Sound waves can have negative or positive effects on plant growth. In this review paper we have summarized the relationship between sound waves and plant growth response. Sound waves with specific frequencies and intensities can have positive effects on various plant biological indices including seed germination, root elongation, plant height, callus growth, cell cycling, signaling transduction systems, enzymatic and hormonal activities, and gene expression.

  20. Synthesis of very small diameter silica nanofibers using sound waves.

    Science.gov (United States)

    Datskos, Panos; Chen, Jihua; Sharma, Jaswinder

    2014-07-14

    Silica nanofibers of an average diameter ≈30 nm and length ≈100 μm have been synthesized using an unprecedented strategy: sound waves. A new phenomenon, spinning off the nanofibers at silica rod tips, is also observed.

  1. Air-borne sound generated by sea waves.

    Science.gov (United States)

    Bolin, Karl; Åbom, Mats

    2010-05-01

    This paper describes a semi-empiric model and measurements of air-borne sound generated by breaking sea waves. Measurements have been performed at the Baltic Sea. Shores with different slopes and sediment types have been investigated. Results showed that the sound pressure level increased from 60 dB at 0.4 m wave height to 78 dB at 2.0 m wave height. The 1/3 octave spectrum was dependent on the surf type. A scaling model based on the dissipated wave power and a surf similarity parameter is proposed and compared to measurements. The predictions show satisfactory agreement to the measurements.

  2. Stable sound wave generation in weakly ionized air medium

    OpenAIRE

    Chizhov, Maxim; Eingorn, Maxim; Kulinskii, Vladimir

    2013-01-01

    We consider the generation of sound waves in the air medium between electrodes at the voltages near electrical breakdown in the presence of the time dependent constituent of the electric field. Within the standard multicomponent hydrodynamic model of the weakly ionized gas it is shown that the generation of sound is possible due to instantaneous character of the ionization equilibrium. The influence of the electronegative ions on the sound intensity is also discussed.

  3. Analyzing Sound Waves Produced by Musical Notes & Chords.

    Science.gov (United States)

    Cassidy, Michael

    This project description is designed to show how graphing calculators and calculator-based laboratories (CBL) can be used to explore topics in the physics of sound. The activities address topics such as sound waves, musical notes, and chords. Teaching notes, calculator instructions, and blackline masters are included. (MM)

  4. Demonstrating Sound Wave Propagation with Candle Flame and Loudspeaker

    Science.gov (United States)

    Hrepic, Zdeslav; Nettles, Corey; Bonilla, Chelsea

    2013-01-01

    The motion of a candle flame in front of a loudspeaker has been suggested as a productive demonstration of the longitudinal wave nature of sound. The demonstration has been used also as a research tool to investigate students' understanding about sound. The underpinning of both applications is the expectation of a horizontal, back-and-forth…

  5. Time dependent wave envelope finite difference analysis of sound propagation

    Science.gov (United States)

    Baumeister, K. J.

    1984-01-01

    A transient finite difference wave envelope formulation is presented for sound propagation, without steady flow. Before the finite difference equations are formulated, the governing wave equation is first transformed to a form whose solution tends not to oscillate along the propagation direction. This transformation reduces the required number of grid points by an order of magnitude. Physically, the transformed pressure represents the amplitude of the conventional sound wave. The derivation for the wave envelope transient wave equation and appropriate boundary conditions are presented as well as the difference equations and stability requirements. To illustrate the method, example solutions are presented for sound propagation in a straight hard wall duct and in a two dimensional straight soft wall duct. The numerical results are in good agreement with exact analytical results.

  6. Scattering of sound waves by a compressible vortex

    Science.gov (United States)

    Colonius, Tim; Lele, Sanjiva K.; Moin, Parviz

    1991-01-01

    Scattering of plane sound waves by a compressible vortex is investigated by direct computation of the two-dimensional Navier-Stokes equations. Nonreflecting boundary conditions are utilized, and their accuracy is established by comparing results on different sized domains. Scattered waves are directly measured from the computations. The resulting amplitude and directivity pattern of the scattered waves is discussed, and compared to various theoretical predictions. For compact vortices (zero circulation), the scattered waves directly computed are in good agreement with predictions based on an acoustic analogy. Strong scattering at about + or - 30 degrees from the direction of incident wave propagation is observed. Back scattering is an order of magnitude smaller than forward scattering. For vortices with finite circulation refraction of the sound by the mean flow field outside the vortex core is found to be important in determining the amplitude and directivity of the scattered wave field.

  7. 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.

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

    Science.gov (United States)

    2015-09-30

    Propeller noise from a light aircraft for low-frequency measurements of the speed of sound in a marine sediment,” J. Comp. Acoust., 10 (4), 445-464...Dispersion Relations for Sound Waves and Shear Waves Michael J. Buckingham Marine Physical Laboratory, Scripps Institution of Oceanography University...propagation in saturated, unconsolidated marine sediments. New focus is on: 1) the dispersion associated with a frequency power law attenuation; 2) wave

  9. Effects of internal waves on sound propagation in the shallow waters of the continental shelves

    OpenAIRE

    Ong, Ming Yi

    2016-01-01

    Approved for public release; distribution is unlimited Sound waves propagating through the oceans are refracted by internal waves. In the shallow waters of the continental shelves, an additional downward refraction of sound waves due to internal waves can cause them to interact more often with the seabed, resulting in additional energy from the sound waves being dissipated into the seabed. This study investigates how internal waves affect sound propagation on the continental shelves. It fi...

  10. Diffusion of Sound Waves in a Turbulent Atmosphere

    Science.gov (United States)

    Lyon, Richard H.

    1960-01-01

    The directional and frequency diffusion of a plane monochromatic 2 sound wave in statistically homogeneous, isotropic, and stationary turbulence is analyzed theoretically. The treatment is based on the diffusion equation for the energy density of sound waves, using the scattering cross section derived by Kraichnan for the type of turbulence assumed here. A form for the frequency-wave number spectrum of the turbulence is adopted which contains the pertinent parameters of the flow and is adapted to ease of calculation. A new approach to the evaluation of the characteristic period of the flow is suggested. This spectrum is then related to the scattering cross section. Finally, a diffusion equation is derived as a small-angle scattering approximation to the rigorous transport equation. The rate of spread of the incident wave in frequency and direction is calculated, as well as the power spectrum and autocorrelation for the wave.

  11. Monograph on propagation of sound waves in curved ducts

    Science.gov (United States)

    Rostafinski, Wojciech

    1991-01-01

    After reviewing and evaluating the existing material on sound propagation in curved ducts without flow, it seems strange that, except for Lord Rayleigh in 1878, no book on acoustics has treated the case of wave motion in bends. This monograph reviews the available analytical and experimental material, nearly 30 papers published on this subject so far, and concisely summarizes what has been learned about the motion of sound in hard-wall and acoustically lined cylindrical bends.

  12. Shallow water sound propagation with surface waves.

    Science.gov (United States)

    Tindle, Chris T; Deane, Grant B

    2005-05-01

    The theory of wavefront modeling in underwater acoustics is extended to allow rapid range dependence of the boundaries such as occurs in shallow water with surface waves. The theory allows for multiple reflections at surface and bottom as well as focusing and defocusing due to reflection from surface waves. The phase and amplitude of the field are calculated directly and used to model pulse propagation in the time domain. Pulse waveforms are obtained directly for all wavefront arrivals including both insonified and shadow regions near caustics. Calculated waveforms agree well with a reference solution and data obtained in a near-shore shallow water experiment with surface waves over a sloping bottom.

  13. Scattering of coherent sound waves by atmospheric turbulence

    Science.gov (United States)

    Chow, P. L.; Liu, C. H.; Maestrello, L.

    1975-01-01

    An analytical study of the propagation of coherent sound waves through an atmosphere containing both mean and fluctuating flow variables is presented. The general flow problem is formulated as a time-dependent wave propagation in a half-space containing the turbulent medium. The coherent acoustic waves are analyzed by a smoothing technique, assuming that mean flow variables vary with the height only. The general equations for the coherent waves are derived, and then applied to two special cases, corresponding to uniform and shear mean flow, respectively. The results show that mean shear and turbulence introduce pronounced effects on the propagation of coherent acoustic disturbances.

  14. Second harmonic plasma emission involving ion sound waves

    Science.gov (United States)

    Cairns, Iver H.

    1987-01-01

    The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L + or - S to T, proceeding in two three-wave steps, L + or - S to L prime and L + L prime to T, where L, S and T denote Langmuir, ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L prime and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.

  15. 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.

  16. On the propagation of sound waves in a stellar wind traversed by periodic strong shocks

    OpenAIRE

    Pijpers, F. P.

    1994-01-01

    It has been claimed that in stellar winds traversed by strong shocks the mechanism for driving the wind by sound wave pressure cannot operate because sound waves cannot propagate past the shocks. It is shown here that sound waves can propagate through shocks in one direction and that this is a sufficient condition for the sound wave pressure mechanism to work. A strong shock amplifies a sound wave passing through it and can drag the sound wave away from the star. It is immaterial for the soun...

  17. Understanding and Affecting Student Reasoning about Sound Waves.

    Science.gov (United States)

    Wittmann, Michael C.; Steinberg, Richard N.; Redish, Edward F.

    2003-01-01

    Explains the design and development of curriculum materials that ask students to think about physics from a different view. These group-learning classroom materials specifically aim to bring about improvement of student understanding of sound waves. (Contains 29 references.) (Author/SOE)

  18. 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.

  19. 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...

  20. 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:

  1. 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.

  2. Sound wave propagation in weakly polydisperse granular materials.

    Science.gov (United States)

    Mouraille, O; Luding, S

    2008-11-01

    Dynamic simulations of wave propagation are performed in dense granular media with a narrow polydisperse size-distribution and a linear contact-force law. A small perturbation is created on one side of a static packing and its propagation, for both P- and S-waves, is examined. A size variation comparable to the typical contact deformation already changes sound propagation considerably. The transmission spectrum becomes discontinuous, i.e., a lower frequency band is transmitted well, while higher frequencies are not, possibly due to attenuation and scattering. This behaviour is qualitatively reproduced for (i) Hertz non-linear contacts, for (ii) frictional contacts, (iii) for a range of smaller amplitudes, or (iv) for larger systems. This proves that the observed wave propagation and dispersion behaviour is intrinsic and not just an artifact of (i) a linear model, (ii) a frictionless packing, (iii) a large amplitude non-linear wave, or (iv) a finite size effect.

  3. 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...

  4. Cylindrical sound wave generated by shock-vortex interaction

    Science.gov (United States)

    Ribner, H. S.

    1985-01-01

    The passage of a columnar vortex broadside through a shock is investigated. This has been suggested as a crude, but deterministic, model of the generation of 'shock noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear waves disposed with radial symmetry. The plane sound waves produced by each shear wave/shock interaction are recombined in the Fourier integral. The waves possess an envelope that is essentially a growing cylindrical sound wave centered at the transmitted vortex. The pressure jump across the nominal radius R = ct attenuates with time as 1/(square root of R) and varies around the arc in an antisymmetric fashion resembling a quadrupole field. Very good agreement, except near the shock, is found with the antisymmetric component of reported interferometric measurements in a shock tube. Beyond the front r approximately equals R is a precursor of opposite sign, that decays like 1/R, generated by the 1/r potential flow around the vortex core. The present work is essentially an extension and update of an early approximate study at M = 1.25. It covers the range (R/core radius) = 10, 100, 1000, and 10,000 for M = 1.25 and (in part) for M = 1.29 and, for fixed (R/core radius) = 1000, the range M = 1.01 to infinity.

  5. Effect of Intense Sound Waves on a Stationary Gas Flame

    Science.gov (United States)

    Hahnemann, H; Ehret, L

    1950-01-01

    Intense sound waves with a resonant frequency of 5000 cycles per second were imposed on a stationary propane-air flame issuing from a nozzle. In addition to a slight increase of the flame velocity, a fundamental change both in the shape of the burning zone and in the flow pattern could be observed. An attempt is made to explain the origin of the variations in the flame configuration on the basis of transition at the nozzle from jet flow to potential flow.

  6. Optical sound wave recording by digital holography with heterodyne technique

    Science.gov (United States)

    Quan, Xiangyu; Rajput, Sudheesh; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2017-06-01

    A visualization technique of sound wave propagation using digital holography with heterodyne technique is presented. In the proposed method, the frequency of the interference pattern in an off-axis digital holography is down converted into the detectable frequency in an image sensor operated at the video frame rate by using the heterodyne interferometer. We present the principle of the recording technique and experimental results are described.

  7. Parametric generation of Alfven and sound waves in the solar atmosphere. Isothermal atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Petrukhin, N.S.; Fajnshtejn, S.M. (Gor' kovskij Politekhnicheskij Inst. (USSR))

    The parametric instability of Alfven and sound waves in an isothermal layer of the solar plasma is investigated. Conditions of the wave generation are found under the condition that the velocities of Alfven waves and isothermal sound are constant. The results obtained are used for the interpretation of attenuation of Alfven wave fluxes in solar spots.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    Komarov, Sergey V.; Sano, Masamichi

    2017-11-01

    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.

  11. Landau damping of sound waves in kinetic magnetohydrodynamics

    Science.gov (United States)

    Ramos, Jesus J.

    2017-10-01

    The Landau damping of slow sound waves propagating parallel to the magnetic field in a homogeneous, collisionless and quasineutral plasma is investigated using the kinetic magnetohydrodynamics formulation of Ref.. In this approach, the electric field is eliminated from a closed, hybrid fluid-kinetic system that ensures automatically the fulfillment of the quasineutrality condition. Considering the time evolution of a parallel-propagating sound wave spatial Fourier mode, this can be cast as a standard, second-order self-adjoint problem, with a continuum spectrum of real and positive squared frequencies. Therefore, a standard resolution of the identity with a single 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 and they are used to derive the damped time evolution of the fluid moments of a wave packet of distribution functions in an initial value problem. As mentioned, the electric field is not used in the treatment of this problem, but it is calculated from its solution after it has been obtained.

  12. Finite-Difference Algorithms For Computing Sound Waves

    Science.gov (United States)

    Davis, Sanford

    1993-01-01

    Governing equations considered as matrix system. Method variant of method described in "Scheme for Finite-Difference Computations of Waves" (ARC-12970). Present method begins with matrix-vector formulation of fundamental equations, involving first-order partial derivatives of primitive variables with respect to space and time. Particular matrix formulation places time and spatial coordinates on equal footing, so governing equations considered as matrix system and treated as unit. Spatial and temporal discretizations not treated separately as in other finite-difference methods, instead treated together by linking spatial-grid interval and time step via common scale factor related to speed of sound.

  13. Temperature oscillations and sound waves in hadronic matter

    Science.gov (United States)

    Wilk, G.; Włodarczyk, Z.

    2017-11-01

    Recent high energy CERN LHC experiments on transverse momenta distributions of produced particles seem to show the existence of some (small but persistent) log-periodic oscillation in the ratios R =σdata(pT) /σfit(pT). We argue that they can provide us with so far unnoticed information on the production process, which can be interpreted as the presence of some kind of sound waves formed during the collision process in the bulk of the produced high density matter.

  14. 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.

  15. Transmission of high frequency sound waves through a slug flow jet

    Science.gov (United States)

    Parthasarathy, S. P.; Vijayaraghavan, A.

    1980-01-01

    An analysis has been performed of sound waves which propagate in a pipe with gas flow. At the pipe exit these waves are partially reflected and the remainder are diffracted. The analysis is carried out by resolving the sound at the exit into its Fourier components and then continuing the solution, which is a combination of elementary plane waves, beyond the exit. These waves are of two types: homogeneous waves which propagate to infinity, and inhomogeneous waves with complex wave numbers which decay. The reflected waves are evaluated from the inhomogeneous waves. At the boundary of the jet, refraction of the elementary plane waves is accounted for and the far field sound is evaluated by the method of stationary phase. Comparisons of the theoretical calculations are made with experimental results and with calculations of other theories.

  16. 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.

  17. Method of synthesizing silica nanofibers using sound waves

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jaswinder K.; Datskos, Panos G.

    2017-08-08

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tsytovich, V.N. [General Physics Institute, Russian Academy of Science Moscow, Moscow (Russian Federation); Watanabe, K. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    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)

  19. The kinetic theory to problem of attenuation transversal sound waves in metal

    OpenAIRE

    Latyshev, A. V.; Yushkanov, A. A.

    2016-01-01

    Earlier electron influence on sound absorption in metal on basis of the assumption of deformation of Fermi-surfaces under the influence of a sound wave was considered. In the present work other approach to this problem will be considered. Our approach based on the account of dynamic (kinetic) interaction of electronic gas with lattice fluctuations. The analysis of influence of electric field on process of attenuation of sound fluctuations is carried out. It is shown that in the long-wave limi...

  20. 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.

  1. Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

    Energy Technology Data Exchange (ETDEWEB)

    IceCube Collaboration; Klein, Spencer

    2009-06-04

    We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.

  2. Excitation of instability waves in a two-dimensional shear layer by sound

    Science.gov (United States)

    Tam, C. K. W.

    1978-01-01

    The excitation of instability waves in a plane compressible shear layer by sound waves is studied. The problem is formulated mathematically as an inhomogeneous boundary-value problem. A general solution for abitrary incident sound wave is found by first constructing the Green's function of the problem. Numerical values of the coupling constants between incident sound waves and excited instability waves for a range of flow Mach number are calculated. The effect of the angle of incidence in the case of a beam of acoustic waves is analyzed. It is found that for moderate subsonic Mach numbers a narrow beam aiming at an angle between 50 to 80 deg to the flow direction is most effective in exciting instability waves.

  3. Molecular hydrodynamics: Vortex formation and sound wave propagation.

    Science.gov (United States)

    Han, Kyeong Hwan; Kim, Changho; Talkner, Peter; Karniadakis, George Em; Lee, Eok Kyun

    2018-01-14

    In the present study, quantitative feasibility tests of the hydrodynamic description of a two-dimensional fluid at the molecular level are performed, both with respect to length and time scales. Using high-resolution fluid velocity data obtained from extensive molecular dynamics simulations, we computed the transverse and longitudinal components of the velocity field by the Helmholtz decomposition and compared them with those obtained from the linearized Navier-Stokes (LNS) equations with time-dependent transport coefficients. By investigating the vortex dynamics and the sound wave propagation in terms of these field components, we confirm the validity of the LNS description for times comparable to or larger than several mean collision times. The LNS description still reproduces the transverse velocity field accurately at smaller times, but it fails to predict characteristic patterns of molecular origin visible in the longitudinal velocity field. Based on these observations, we validate the main assumptions of the mode-coupling approach. The assumption that the velocity autocorrelation function can be expressed in terms of the fluid velocity field and the tagged particle distribution is found to be remarkably accurate even for times comparable to or smaller than the mean collision time. This suggests that the hydrodynamic-mode description remains valid down to the molecular scale.

  4. 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.

  5. Molecular hydrodynamics: Vortex formation and sound wave propagation

    Science.gov (United States)

    Han, Kyeong Hwan; Kim, Changho; Talkner, Peter; Karniadakis, George Em; Lee, Eok Kyun

    2018-01-01

    In the present study, quantitative feasibility tests of the hydrodynamic description of a two-dimensional fluid at the molecular level are performed, both with respect to length and time scales. Using high-resolution fluid velocity data obtained from extensive molecular dynamics simulations, we computed the transverse and longitudinal components of the velocity field by the Helmholtz decomposition and compared them with those obtained from the linearized Navier-Stokes (LNS) equations with time-dependent transport coefficients. By investigating the vortex dynamics and the sound wave propagation in terms of these field components, we confirm the validity of the LNS description for times comparable to or larger than several mean collision times. The LNS description still reproduces the transverse velocity field accurately at smaller times, but it fails to predict characteristic patterns of molecular origin visible in the longitudinal velocity field. Based on these observations, we validate the main assumptions of the mode-coupling approach. The assumption that the velocity autocorrelation function can be expressed in terms of the fluid velocity field and the tagged particle distribution is found to be remarkably accurate even for times comparable to or smaller than the mean collision time. This suggests that the hydrodynamic-mode description remains valid down to the molecular scale.

  6. Generation of sound by Alfven waves with random phases in the solar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Petrukhin, N.S.; Fainshtein, S.M.

    1976-11-01

    The problem of the excitation of sound by Alfven waves meeting in the solar plasma is discussed. Kinetic equations for the interacting waves are derived and analyzed on the assumption that the Alfven waves have random phases. Estimates are given which show the possibility of the generation of LF-pulsations in the solar atmosphere.

  7. High-frequency sound waves to eliminate a horizon in the mixmaster universe.

    Science.gov (United States)

    Chitre, D. M.

    1972-01-01

    From the linear wave equation for small-amplitude sound waves in a curved space-time, there is derived a geodesiclike differential equation for sound rays to describe the motion of wave packets. These equations are applied in the generic, nonrotating, homogeneous closed-model universe (the 'mixmaster universe,' Bianchi type IX). As for light rays described by Doroshkevich and Novikov (DN), these sound rays can circumnavigate the universe near the singularity to remove particle horizons only for a small class of these models and in special directions. Although these results parallel those of DN, different Hamiltonian methods are used for treating the Einstein equations.

  8. Source and listener directivity for interactive wave-based sound propagation.

    Science.gov (United States)

    Mehra, Ravish; Antani, Lakulish; Kim, Sujeong; Manocha, Dinesh

    2014-04-01

    We present an approach to model dynamic, data-driven source and listener directivity for interactive wave-based sound propagation in virtual environments and computer games. Our directional source representation is expressed as a linear combination of elementary spherical harmonic (SH) sources. In the preprocessing stage, we precompute and encode the propagated sound fields due to each SH source. At runtime, we perform the SH decomposition of the varying source directivity interactively and compute the total sound field at the listener position as a weighted sum of precomputed SH sound fields. We propose a novel plane-wave decomposition approach based on higher-order derivatives of the sound field that enables dynamic HRTF-based listener directivity at runtime. We provide a generic framework to incorporate our source and listener directivity in any offline or online frequency-domain wave-based sound propagation algorithm. We have integrated our sound propagation system in Valve's Source game engine and use it to demonstrate realistic acoustic effects such as sound amplification, diffraction low-passing, scattering, localization, externalization, and spatial sound, generated by wave-based propagation of directional sources and listener in complex scenarios. We also present results from our preliminary user study.

  9. On the interaction of waves carrying light, sound and small particles : wave-based methods for miniature laboratories and fast optical sensing

    NARCIS (Netherlands)

    van 't Oever, Jan Joannes Frederik

    2018-01-01

    The main theme of this thesis is waves: sound waves for trapping, guiding or mixing suspended particles, and light waves for making sound waves and rough surfaces visible. One of the important functions on a Lab-on-a-Chip system is suspended particle manipulation and concentration. One way to

  10. Chiral heat wave in cold Fermi liquid and modified zero sound

    Science.gov (United States)

    Frenklakh, D.; Gorsky, A.

    2017-08-01

    We discuss kinetic equations involving the anomalous terms responsible for the chiral anomaly. The general chiral heat wave in cold Fermi liquid is described and the modification of the anomalous zero sound at small temperature and vorticity is found.

  11. New soliton solutions of the system of equations for the ion sound and Langmuir waves

    Directory of Open Access Journals (Sweden)

    Seyma Tuluce Demiray

    2016-11-01

    Full Text Available This study is based on new soliton solutions of the system of equations for the ion sound wave under the action of the ponderomotive force due to high-frequency field and for the Langmuir wave. The generalized Kudryashov method (GKM, which is one of the analytical methods, has been tackled for finding exact solutions of the system of equations for the ion sound wave and the Langmuir wave. By using this method, dark soliton solutions of this system of equations have been obtained. Also, by using Mathematica Release 9, some graphical simulations were designed to see the behavior of these solutions.

  12. Sound generation and upstream influence due to instability waves interacting with non-uniform mean flows

    Science.gov (United States)

    Goldstein, M. E.

    1984-01-01

    Attention is given to the sound produced by artificially excited, spatially growing instability waves on subsonic shear layers. Real flows that always diverge in the downstream direction allow sound to be produced by the interaction of the instability waves with the resulting streamwise variations of the flow. The upstream influence, or feedback, can interact with the splitter plate lip to produce a downstream-propagating instability wave that may under certain conditions be the same instability wave that originally generated the upstream influence. The present treatment is restricted to very low Mach number flows, so that compressibility effects can only become important over large distances.

  13. Effective isolation of primo vessels in lymph using sound- and ultrasonic-wave stimulation.

    Science.gov (United States)

    Park, Do-Young; Lee, Hye-Rie; Rho, Min-Suk; Lee, Sang-Suk

    2014-12-01

    The effects of stimulation with sound and ultrasonic waves of a specific bandwidth on the microdissection of primo vessels in lymphatic vessels of rabbit were investigated. The primo vessels stained with alcian-blue dye injected in the lymph nodes were definitely visualized and more easily isolated by sound-wave vibration and ultrasonic stimulation applied to rabbits at various frequencies and intensities. With sound wave at 7 Hz and ultrasonic waves at 2 MHz, the probability of detecting the primo vessels was improved to 90%; however, without wave stimulation the probability of discovering primo vessels was about 50% only. Sound and ultrasonic waves at specific frequency bands should be effective for microdissection of the primo vessels in the abdominal lymph of rabbit. We suggest that oscillation of the primo vessels by sound and ultrasonic waves may be useful to visualize specific primo structure, and wave vibration can be a very supportive process for observation and isolation of the primo vessels of rabbits. Copyright © 2014. Published by Elsevier B.V.

  14. Sound Radiated by a Wave-Like Structure in a Compressible Jet

    Science.gov (United States)

    Golubev, V. V.; Prieto, A. F.; Mankbadi, R. R.; Dahl, M. D.; Hixon, R.

    2003-01-01

    This paper extends the analysis of acoustic radiation from the source model representing spatially-growing instability waves in a round jet at high speeds. Compared to previous work, a modified approach to the sound source modeling is examined that employs a set of solutions to linearized Euler equations. The sound radiation is then calculated using an integral surface method.

  15. Effect of disorder on bulk sound wave speed : A multiscale spectral analysis

    NARCIS (Netherlands)

    Shrivastava, Rohit Kumar; Luding, Stefan

    2017-01-01

    Disorder of size (polydispersity) and mass of discrete elements or particles in randomly structured media (e.g., granular matter such as soil) has numerous effects on the materials' sound propagation characteristics. The influence of disorder on energy and momentum transport, the sound wave speed

  16. Influence of Sound Wave Stimulation on the Growth of Strawberry in Sunlight Greenhouse

    Science.gov (United States)

    Qi, Lirong; Teng, Guanghui; Hou, Tianzhen; Zhu, Baoying; Liu, Xiaona

    In this paper, we adopt the QGWA-03 plant audio apparatus to investigate the sound effects on strawberry in the leaf area, the photosynthetic characteristics and other physiological indexes. It was found that when there were no significant differences between the circumstances of the two sunlight greenhouses, the strawberry after the sound wave stimulation grew stronger than in the control and its leaf were deeper green, and shifted to an earlier time about one week to blossom and bear fruit. It was also found that the resistance of strawberry against disease and insect pest were enhanced. The experiment results show that sound wave stimulation can certainly promote the growth of plants.

  17. 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.

  18. 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

  19. Nonlinear interactions in superfluid dynamics: Nonstationary heat transfer due to second sound shock waves

    Science.gov (United States)

    Liepmann, H. W.; Torczynski, J. R.

    1983-01-01

    Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.

  20. Enhancement of CO2 capture in limestone and dolomite granular beds by high intensity sound waves

    Directory of Open Access Journals (Sweden)

    Valverde Jose Manuel

    2017-01-01

    Full Text Available The calcium looping (CaL process, based on the calcination/carbonation of CaCO3 at high temperatures, has emerged in the last years as a potentially low cost technology for CO2 capture. In this work, we show that the application of high intensity sound waves to granular beds of limestone and dolomite in a CaL reactor enhances significantly their multicycle CO2 capture capacity. Sound waves are applied either during the calcination stage of each CaL cycle or in the carbonation stage. The effect of sound is to intensify the transfer of heat, mass and momentum and is more marked when sound is applied during calcination by promoting CaO regeneration. The application of sound would allow reducing the calcination temperature thereby mitigating the decay of capture capacity with the number of cycles and reducing the energy penalty of the technology.

  1. Enhancement of CO2 capture in limestone and dolomite granular beds by high intensity sound waves

    Science.gov (United States)

    Valverde, Jose Manuel; Perez-Ebri, Jose Manuel; Sanchez-Quintanilla, Miguel Angel

    2017-06-01

    The calcium looping (CaL) process, based on the calcination/carbonation of CaCO3 at high temperatures, has emerged in the last years as a potentially low cost technology for CO2 capture. In this work, we show that the application of high intensity sound waves to granular beds of limestone and dolomite in a CaL reactor enhances significantly their multicycle CO2 capture capacity. Sound waves are applied either during the calcination stage of each CaL cycle or in the carbonation stage. The effect of sound is to intensify the transfer of heat, mass and momentum and is more marked when sound is applied during calcination by promoting CaO regeneration. The application of sound would allow reducing the calcination temperature thereby mitigating the decay of capture capacity with the number of cycles and reducing the energy penalty of the technology.

  2. Time Domain Simulation of Sound Waves Using Smoothed Particle Hydrodynamics Algorithm with Artificial Viscosity

    Directory of Open Access Journals (Sweden)

    Xu Li

    2015-06-01

    Full Text Available Smoothed particle hydrodynamics (SPH, as a Lagrangian, meshfree method, is supposed to be useful in solving acoustic problems, such as combustion noise, bubble acoustics, etc., and has been gradually used in sound wave computation. However, unphysical oscillations in the sound wave simulation cannot be ignored. In this paper, an artificial viscosity term is added into the standard SPH algorithm used for solving linearized acoustic wave equations. SPH algorithms with or without artificial viscosity are both built to compute sound propagation and interference in the time domain. Then, the effects of the smoothing kernel function, particle spacing and Courant number on the SPH algorithms of sound waves are discussed. After comparing SPH simulation results with theoretical solutions, it is shown that the result of the SPH algorithm with the artificial viscosity term added attains good agreement with the theoretical solution by effectively reducing unphysical oscillations. In addition, suitable computational parameters of SPH algorithms are proposed through analyzing the sound pressure errors for simulating sound waves.

  3. Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis

    Science.gov (United States)

    Turner, T. N.

    1979-01-01

    Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.

  4. Wave field synthesis of moving virtual sound sources with complex radiation properties.

    Science.gov (United States)

    Ahrens, Jens; Spors, Sascha

    2011-11-01

    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  5. Measuring oblique incidence sound absorption using a local plane wave assumption

    NARCIS (Netherlands)

    Kuipers, E.R.; Wijnant, Ysbrand H.; de Boer, Andries

    2014-01-01

    In this paper a method for the measurement of the oblique incidence sound absorption coefficient is presented. It is based on a local field assumption, in which the acoustic field is locally approximated by one incident- and one specularly reflected plane wave. The amplitudes of these waves can be

  6. 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…

  7. Parametric generation of Alfven and sound waves in the solar atmosphere. A homogeneous medium

    Energy Technology Data Exchange (ETDEWEB)

    Petrukhin, N.S.; Fajnshtejn, S.M. (Gor' kovskij Politekhnicheskij Inst. (USSR))

    The parametric generation of Alfven and sound waves in a homogeneous plasma layer with constant values of Alfven (Csub(A)) and sound (Csub(S)) velocities is considered. The two cases are studied. In the first case Csub(A) > Csub(S) which one is realized in active regions. The second one Csub(S) > Csub(A) is taken place in the quiet chromosphere. Conditions are found out for excitation of waves at different ratios of magnetic and gas-kinetic pressures. Coefficients of the nonlinear wave scattering in a layer of the solar plasma have been found.

  8. Quantitative calibration of sound pressure in ultrasonic standing waves using the Schlieren method.

    Science.gov (United States)

    Xu, Zheng; Chen, Hao; Yan, Xu; Qian, Menglu; Cheng, Qian

    2017-08-21

    We investigated the use of the Schlieren method to calibrate the sound pressure in an ultrasonic standing-wave field. Specifically, we derived an equation to calculate the light intensity of the diffraction fringe induced by the standing-wave field. The results indicated that the sound pressure in the standing-wave field relates to the light intensity of the diffraction fringe. Simulations and experiments were conducted to verify the theoretical calculation. We demonstrated that the ratio of the light intensity of different diffraction orders relates to the sound pressure amplitude, allowing the pressure amplitude to be calibrated with the Schlieren method. Therefore, this work presents a non-intrusive calibration method that is particularly suitable for calibrating high-frequency ultrasonic standing-wave fields.

  9. 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.

  10. Intensity statistics of very high frequency sound scattered from wind-driven waves.

    Science.gov (United States)

    Walstead, Sean P; Deane, Grant B

    2016-05-01

    The interaction of vhf 100-1000 kHz underwater sound with the ocean surface is explored. The bistatic forward scatter of 300 kHz sound is measured in a wind driven wave channel. Fluctuations in arrival amplitude are described by the scintillation index (SI) which is a measure of arrival intensity variance. SI initially increases with wind speed but eventually saturates to a value of 0.5 when the root-mean-square (rms) roughness is 0.5 mm. An adjusted scintillation index (SI*) is suggested that accounts for the multiple arrivals and properly saturates to a value of 1. Fluctuations in arrival time do not saturate and increase proportionately to the dominant surface wave component. Forward scattering is modeled at frequencies ranging from 50 to 2000 kHz using the Helmholtz-Kirchhoff integral with surface wave realizations derived from wave gauge data. The amplitude and temporal statistics of the simulated scattering agree well with measured data. Intensity saturation occurs at lower wind speeds for higher frequency sound. Both measured and modeled vhf sound is characterized by many surface arrivals at saturation. Doppler shifts associated with wave motion are expected to vary rapidly for vhf sound however further analysis is required.

  11. Sound wave propagation in weakly polydisperse granular materials

    NARCIS (Netherlands)

    Mouraille, O.J.P.; Luding, Stefan

    2008-01-01

    Dynamic simulations of wave propagation are performed in dense granular media with a narrow polydisperse size-distribution and a linear contact-force law. A small perturbation is created on one side of a static packing and its propagation, for both P- and S-waves, is examined. A size variation

  12. Sound waves in two-dimensional ducts with sinusoidal walls

    Science.gov (United States)

    Nayfeh, A. H.

    1974-01-01

    The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.

  13. Sound power spectrum and wave drag of a propeller in flight

    Science.gov (United States)

    Hanson, D. B.

    1989-01-01

    Theory is presented for the sound power and sound power spectrum of a single rotation propeller in forward flight. Calculations are based on the linear wave equation with sources distributed over helicoidal surfaces to represent effects of blade thickness and steady loading. Sound power is distributed continuously over frequecy, as would be expected from Doppler effects, rather than in discrete harmonics. The theory is applied to study effects of sweep and Mach number in propfans. An acoustic efficiency is defined as the ratio of radiated sound power to shaft input power. This value is the linear estimate of the effect of wave drag due to the supersonic blade section speeds. It is shown that the acoustic efficiency is somewhat less than 1 percent for a well designed propfan.

  14. 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

  15. Tracking kidney stones with sound during shock wave lithotripsy

    Science.gov (United States)

    Kracht, Jonathan M.

    The prevalence of kidney stones has increased significantly over the past decades. One of the primary treatments for kidney stones is shock wave lithotripsy which focuses acoustic shock waves onto the stone in order to fragment it into pieces that are small enough to pass naturally. This typically requires a few thousand shock waves delivered at a rate of about 2 Hz. Although lithotripsy is the only non-invasive treatment option for kidney stories, both acute and chronic complications have been identified which could be reduced if fewer shock waves were used. One factor that could be used to reduce the number of shock waves is accounting for the motion of the stone which causes a portion of the delivered shock waves to miss the stone, yielding no therapeutic benefit. Therefore identifying when the stone is not in focus would allow tissue to be spared without affecting fragmentation. The goal of this thesis is to investigate acoustic methods to track the stone in real-time during lithotripsy in order to minimize poorly-targeted shock waves. A relatively small number of low frequency ultrasound transducers were used in pulse-echo mode and a novel optimization routine based on time-of-flight triangulation is used to determine stone location. It was shown that the accuracy of the localization may be estimated without knowing the true stone location. This method performed well in preliminary experiments but the inclusion of tissue-like aberrating layers reduced the accuracy of the localization. Therefore a hybrid imaging technique employing DORT (Decomposition of the Time Reversal Operator) and the MUSIC (Multiple Signal Classification) algorithm was developed. This method was able to localize kidney stories to within a few millimeters even in the presence of an aberrating layer. This would be sufficient accuracy for targeting lithotripter shock waves. The conclusion of this work is that tracking kidney stones with low frequency ultrasound should be effective clinically.

  16. The Impact of Sound on Electroencephalographic Waves during Sleep in Patients Suffering from Tinnitus.

    Science.gov (United States)

    Pedemonte, Marisa; Testa, Martín; Díaz, Marcela; Suárez-Bagnasco, Diego

    2014-09-01

    Based on the knowledge that sensory processing continues during sleep and that a relationship exists between sleep and learning, a new strategy for treatment of idiopathic subjective tinnitus, consisted of customized sound stimulation presented during sleep, was tested. It has been previously shown that this treatment induces a sustained decrease in tinnitus intensity; however, its effect on brain activity has not yet been studied. In this work, we compared the impact of sound stimulation in tinnitus patients in the different sleep stages. Ten patients with idiopathic tinnitus were treated with sound stimulation mimicking tinnitus during sleep. Power spectra and intra- and inter-hemispheric coherence of electroencephalographic waves from frontal and temporal electrodes were measured with and without sound stimulation for each sleep stage (stages N2 with sleep spindles; N3 with slow wave sleep and REM sleep with Rapid Eye Movements). The main results found were that the largest number of changes, considering both the power spectrum and wave׳s coherence, occurred in stages N2 and N3. The delta and theta bands were the most changed, with important changes also in coherence of spindles during N2. All changes were more frequent in temporal areas. The differences between the two hemispheres do not depend, at least exclusively, on the side where the tinnitus is perceived and, hence, of the stimulated side. These results demonstrate that sound stimulation during sleep in tinnitus patients׳ influences brain activity and open an avenue for investigating the mechanism underlying tinnitus and its treatment.

  17. Observation of sound focusing and defocusing due to propagating nonlinear internal waves.

    Science.gov (United States)

    Luo, J; Badiey, M; Karjadi, E A; Katsnelson, B; Tskhoidze, A; Lynch, J F; Moum, J N

    2008-09-01

    Fluctuations of the low frequency sound field in the presence of an internal solitary wave packet during the Shallow Water '06 experiment are analyzed. Acoustic, environmental, and on-board ship radar image data were collected simultaneously before, during, and after a strong internal solitary wave packet passed through the acoustic track. Preliminary analysis of the acoustic wave temporal intensity fluctuations agrees with previously observed phenomena and the existing theory of the horizontal refraction mechanism, which causes focusing and defocusing when the acoustic track is nearly parallel to the front of the internal waves [J. Acoust. Soc. Am., 122(2), pp. 747-760 (2007)].

  18. Adaptive wave field synthesis for active sound field reproduction: experimental results.

    Science.gov (United States)

    Gauthier, Philippe-Aubert; Berry, Alain

    2008-04-01

    Sound field reproduction has applications in music reproduction, spatial audio, sound environment reproduction, and experimental acoustics. Sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. The room response thus reduces the quality of the physical sound field reproduction by WFS. In recent research papers, adaptive wave field synthesis (AWFS) was defined as a potential solution to compensate for these quality reductions from which WFS objective performance suffers. In this paper, AWFS is experimentally investigated as an active sound field reproduction system with a limited number of reproduction error sensors to compensate for the response of the listening environment. Two digital signal processing algorithms for AWFS are used for comparison purposes, one of which is based on independent radiation mode control. AWFS performed propagating sound field reproduction better than WFS in three tested reproduction spaces (hemianechoic chamber, standard laboratory space, and reverberation chamber).

  19. Dynamics of ion sound waves in the front of the terrestrial bow shock

    Directory of Open Access Journals (Sweden)

    I. Giagkiozis

    2011-05-01

    Full Text Available Single spacecraft measurements from the Cluster 3 satellite are used to identify nonlinear processes in ion-sound turbulence observed within the front of the quasiperpendicular terrestrial bow shock. Ion sound waves possess spatial scales that are too small for the efficient use of multipoint measurements on inter-satellite separation scales. However, it is shown how frequency domain modelling can be applied to single spacecraft electric field data obtained using the EFW internal burst mode. The resulting characteristics of the nonlinear processes are used to argue about the possible wave sources and investigate their dynamics.

  20. 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

  1. Dynamic of Langmuir and Ion-Sound Waves in Type 3 Solar Radio Sources

    Science.gov (United States)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The evolution of Langmuir and ion-sound waves in type 3 sources is investigated, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. The resulting prediction for the electrostatic decay threshold is consistent with the observed high-field cutoff in the Langmuir field distribution. It is shown that the conditions in the solar wind do not allow a steady state to be attained; rather, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be fast enough to saturate the growth of the parent Langmuir waves in the available interaction time. The resulting levels of product Langmuir and ion-sound waves are estimated theoretically and shown to be consistent with in situ ISEE 3 observations of type 3 events at 1 AU. Nonlinear interactions slave the growth and decay of product sound waves to that of the product Langmuir waves. The resulting probability distribution of ion-sound field strengths is predicted to have a flat tail extending to a high-field cutoff. This prediction is consistent with statistics derived here from ISEE 3 observations. Agreement is also found between the frequencies of the observed waves and predictions for the product S waves. The competing processes of nonlinear wave collapse and quasilinear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth. When wave and beam inhomogeneities are accounted for, arguments from quasi-linear relaxation yield an upper bound on the Langmuir fields that is too high to be relevant. Nor are the criteria for direct wave collapse of the beam-driven waves met, consistent with earlier simulation results that imply that this process is not responsible for saturation of the beam instability. Indeed, even

  2. Propagation of sound waves in tubes of noncircular cross section

    Science.gov (United States)

    Richards, W. B.

    1986-01-01

    Plane-acoustic-wave propagation in small tubes with a cross section in the shape of a flattened oval is described. Theoretical descriptions of a plane wave propagating in a tube with circular cross section and between a pair of infinite parallel plates, including viscous and thermal damping, are expressed in similar form. For a wide range of useful duct sizes, the propagation constant (whose real and imaginary parts are the amplitude attenuation rate and the wave number, respectively) is very nearly the same function of frequency for both cases if the radius of the circular tube is the same as the distance between the parallel plates. This suggests that either a circular-cross-section model or a flat-plate model can be used to calculate wave propagation in flat-oval tubing, or any other shape tubing, if its size is expressed in terms of an equivalent radius, given by g = 2 x (cross-sectional area)/(length of perimeter). Measurements of the frequency response of two sections of flat-oval tubing agree with calculations based on this idea. Flat-plate formulas are derived, the use of transmission-line matrices for calculations of plane waves in compound systems of ducts is described, and examples of computer programs written to carry out the calculations are shown.

  3. 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.

  4. 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.

  5. Sound waves induce Volkov-like states, band structure and collimation effect in graphene

    OpenAIRE

    Oliva-Leyva, M.; Naumis, G. G.

    2015-01-01

    We find exact states of graphene quasiparticles under a time-dependent deformation (sound wave), whose propagation velocity is smaller than the Fermi velocity. To solve the corresponding effective Dirac equation, we adapt the Volkov-like solutions for relativistic fermions in a medium under a plane electromagnetic wave. The corresponding electron-deformation quasiparticle spectrum is determined by the solutions of a Mathieu equation resulting in band tongues warped in the surface of the Dirac...

  6. Magneto-acoustic ceramics for parametric sound wave phase conjugators

    Science.gov (United States)

    Brysev; Pernod; Preobrazhensky

    2000-03-01

    The paper reflects the recent experimental results on the elaboration and study of active materials for magneto-acoustic phase conjugators (MAPCs). The results of complex measurements of MAPC parameters are demonstrated on typical samples of NiFe2O4 magnetostrictive ceramics. The mechanism of strong dispersion of gain increments and output power of MAPCs is studied and explained by dispersion of critical values of the parametric modulation depth of sound velocity. A maximum output power 240 W at frequency 5 MHz is obtained for active element MAPC with critical current Ic = 9 A and electrical Q-factor equal to 80.

  7. Analog of Optical Elements for Sound Waves in Air

    Science.gov (United States)

    Gluck, Paul; Perkalskis, Benjamin

    2009-01-01

    Optical elements manipulate light waves. They may be used to focus the light or to change the phase, the polarization, the direction, or the intensity of light. Many of these functions are often demonstrated with microwaves, since the devices normally available in teaching laboratories produce wavelengths in the centimeter range and are therefore…

  8. Softening of stressed granular packings with resonant sound waves.

    Science.gov (United States)

    Reichhardt, C J Olson; Lopatina, L M; Jia, X; Johnson, P A

    2015-08-01

    We perform numerical simulations of a two-dimensional bidisperse granular packing subjected to both a static confining pressure and a sinusoidal dynamic forcing applied by a wall on one edge of the packing. We measure the response experienced by a wall on the opposite edge of the packing and obtain the resonant frequency of the packing as the static or dynamic pressures are varied. Under increasing static pressure, the resonant frequency increases, indicating a velocity increase of elastic waves propagating through the packing. In contrast, when the dynamic amplitude is increased for fixed static pressure, the resonant frequency decreases, indicating a decrease in the wave velocity. This occurs both for compressional and for shear dynamic forcing and is in agreement with experimental results. We find that the average contact number Zc at the resonant frequency decreases with increasing dynamic amplitude, indicating that the elastic softening of the packing is associated with a reduced number of grain-grain contacts through which the elastic waves can travel. We image the excitations created in the packing and show that there are localized disturbances or soft spots that become more prevalent with increasing dynamic amplitude. Our results are in agreement with experiments on glass bead packings and earth materials such as sandstone and granite and may be relevant to the decrease in elastic wave velocities that has been observed to occur near fault zones after strong earthquakes, in surficial sediments during strong ground motion, and in structures during earthquake excitation.

  9. Modulations of MLT turbulence by waves observed during the WADIS sounding rocket project.

    Science.gov (United States)

    Strelnikov, Boris; Latteck, Ralph; Strelnikova, Irina; Lübken, Franz-Josef; Baumgarten, Gerd; Rapp, Markus

    2017-04-01

    The WADIS project (WAve propagation and DISsipation in the middle atmosphere) aimed at studying waves, their dissipation, and effects on trace constituents. Among other things, it addressed the question of the variability of MLT turbulence, both in time and space. A unique feature of the WADIS project was multi-point turbulence sounding applying different measurement techniques including rocket-borne ionization gauges, VHF MAARSY radar, and VHF EISCAT radar in Tromsø. The project comprised two sounding rocket campaigns conducted at the Andøya Space Center (69 °N, 16 °E). One sounding rocket was launched in summer 2013 and one in winter 2015. The joint in-situ and ground-based observations showed horizontal variability of the turbulence field in the MLT at scales from a few to 100 km. We found that the turbulence dissipation rate varied in space in a wave-like manner both horizontally and in the vertical direction. This wave-like modulation reveals the same vertical wavelengths as those seen in gravity waves. We also found that vertical mean value of radar turbulence observations reveals wave-like modulation in time domain. This time variability results in up to two orders of magnitude change of the energy dissipation values with periods of 24 h. It also shows 12 h and shorter ( hours) modulations resulting in one decade variation. In this paper we present recent measurement results of turbulence-mean flow interaction and discuss possible reasons of the observed modulations.

  10. Effect of disorder on bulk sound wave speed: a multiscale spectral analysis

    Science.gov (United States)

    Shrivastava, Rohit Kumar; Luding, Stefan

    2017-08-01

    Disorder of size (polydispersity) and mass of discrete elements or particles in randomly structured media (e.g., granular matter such as soil) has numerous effects on the materials' sound propagation characteristics. The influence of disorder on energy and momentum transport, the sound wave speed and its low-pass frequency-filtering characteristics is the subject of this study. The goal is understanding the connection between the particle-microscale disorder and dynamics and the system-macroscale wave propagation, which can be applied to nondestructive testing, seismic exploration of buried objects (oil, mineral, etc.) or to study the internal structure of the Earth. To isolate the longitudinal P-wave mode from shear and rotational modes, a one-dimensional system of equally sized elements or particles is used to study the effect of mass disorder alone via (direct and/or ensemble averaged) real time signals, signals in Fourier space, energy and dispersion curves. Increase in mass disorder (where disorder has been defined such that it is independent of the shape of the probability distribution of masses) decreases the sound wave speed along a granular chain. Energies associated with the eigenmodes can be used to obtain better quality dispersion relations for disordered chains; these dispersion relations confirm the decrease in pass frequency and wave speed with increasing disorder acting opposite to the wave acceleration close to the source.

  11. Horizontal ducting of sound by curved nonlinear internal gravity waves in the continental shelf areas.

    Science.gov (United States)

    Lin, Ying-Tsong; McMahon, Kara G; Lynch, James F; Siegmann, William L

    2013-01-01

    The acoustic ducting effect by curved nonlinear gravity waves in shallow water is studied through idealized models in this paper. The internal wave ducts are three-dimensional, bounded vertically by the sea surface and bottom, and horizontally by aligned wavefronts. Both normal mode and parabolic equation methods are taken to analyze the ducted sound field. Two types of horizontal acoustic modes can be found in the curved internal wave duct. One is a whispering-gallery type formed by the sound energy trapped along the outer and concave boundary of the duct, and the other is a fully bouncing type due to continual reflections from boundaries in the duct. The ducting condition depends on both internal-wave and acoustic-source parameters, and a parametric study is conducted to derive a general pattern. The parabolic equation method provides full-field modeling of the sound field, so it includes other acoustic effects caused by internal waves, such as mode coupling/scattering and horizontal Lloyd's mirror interference. Two examples are provided to present internal wave ducts with constant curvature and meandering wavefronts.

  12. Sound field reconstruction within an entire cavity by plane wave expansions using a spherical microphone array.

    Science.gov (United States)

    Wang, Yan; Chen, Kean

    2017-10-01

    A spherical microphone array has proved effective in reconstructing an enclosed sound field by a superposition of spherical wave functions in Fourier domain. It allows successful reconstructions surrounding the array, but the accuracy will be degraded at a distance. In order to extend the effective reconstruction to the entire cavity, a plane-wave basis in space domain is used owing to its non-decaying propagating characteristic and compared with the conventional spherical wave function method in a low frequency sound field within a cylindrical cavity. The sensitivity to measurement noise, the effects of the numbers of plane waves, and measurement positions are discussed. Simulations show that under the same measurement conditions, the plane wave function method is superior in terms of reconstruction accuracy and data processing efficiency, that is, the entire sound field imaging can be achieved by only one time calculation instead of translations of local sets of coefficients with respect to every measurement position into a global one. An experiment was conducted inside an aircraft cabin mock-up for validation. Additionally, this method provides an alternative possibility to recover the coefficients of high order spherical wave functions in a global coordinate system without coordinate translations with respect to local origins.

  13. Wave propagation in and sound transmission through sandwich plates

    Science.gov (United States)

    Nilsson, A. C.

    1990-04-01

    Some dynamical and acoustical properties of sandwich plates are investigated. The types of sandwich elements discussed are three-layered plates with a thick lightweight core, with thin and comparatively stiff laminates bonded to each side of the core. In the model derived it is assumed that the laminates and core are isotropic. The laminates are treated as thin plates, whereas the deflection in the core is described by means of the general field equations. This means that bending shear and rotation, as well as longitudinal deflection, are considered in the core. Wavenumbers, loss factors and apparent bending stiffness for symmetric and asymmetric plates are derived. In addition, the sound transmission loss for sandwich plates is discussed. Measured and predicted results are compared. It is found that bending stiffness and loss factor not only depend on material parameters and plate geometries but also on frequency. The core thickness is very critical for the sound transmission loss of a sandwich plate. Sandwich plates are frequently used in the shipbuilding industry for light and fast passenger vessels. The effects of a fluid load on a sandwich plate is therefore also included.

  14. Illustrations and Supporting Texts for Sound Standing Waves of Air Columns in Pipes in Introductory Physics Textbooks

    Science.gov (United States)

    Zeng, Liang; Smith, Chris; Poelzer, G. Herold; Rodriguez, Jennifer; Corpuz, Edgar; Yanev, George

    2014-01-01

    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…

  15. Numerical study of three-dimensional sound reflection from corrugated surface waves.

    Science.gov (United States)

    Choo, Youngmin; Song, H C; Seong, Woojae

    2016-10-01

    When a sound wave propagates in a water medium bounded by a smooth surface wave, reflection from a wave crest can lead to focusing and result in rapid variation of the received waveform as the surface wave moves [Tindle, Deane, and Preisig, J. Acoust. Soc. Am. 125, 66-72 (2009)]. In prior work, propagation paths have been constrained to be in a plane parallel to the direction of corrugated surface waves, i.e., a two-dimensional (2-D) propagation problem. In this paper, the azimuthal dependence of sound propagation as a three-dimensional (3-D) problem is investigated using an efficient, time-domain Helmholtz-Kirchhoff integral formulation. When the source and receiver are in the plane orthogonal to the surface wave direction, the surface wave curvature vanishes in conventional 2-D treatments and the flat surface simply moves up and down, resulting in minimal temporal variation of the reflected signal intensity. On the other hand, the 3-D propagation analysis reveals that a focusing phenomenon occurs in the reflected signal due to the surface wave curvature formed along the orthogonal plane, i.e., out-of-plane scattering.

  16. Three-in-One Resonance Tube for Harmonic Series Sound Wave Experiments

    Science.gov (United States)

    Jaafar, Rosly; Nazihah Mat Daud, Anis; Ali, Shaharudin; Kadri Ayop, Shahrul

    2017-01-01

    In this study we constructed a special three-in-one resonance tube for a harmonic series sound waves experiment. It is designed for three different experiments: both-open-end, one-closed-end and both-closed-end tubes. The resonance tube consists of a PVC conduit with a rectangular hole, rubber tube, plastic stopper with an embedded microphone and…

  17. 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...... influence of GLOFs in a specific catchment impede a simple upscaling of sediment fluxes from individual catchments toward a total sediment flux into the Young Sound....

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

    Science.gov (United States)

    Kroon, Aart; Abermann, Jakob; Bendixen, Mette; Lund, Magnus; Sigsgaard, Charlotte; Skov, Kirstine; Hansen, Birger Ulf

    2017-02-01

    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, 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 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 influence of GLOFs in a specific catchment impede a simple upscaling of sediment fluxes from individual catchments toward a total sediment flux into the Young Sound.

  19. Sound Wave Propagation Analysis Using FDTD for Contaminated Insulator Discharge Noise

    Science.gov (United States)

    Matsumoto, Takaie; Shimoda, Takeshi

    Discharge noises caused by contaminated insulator string were studied using anechoic room where the difference of the noise waveform due to insulator shape was found. In this study, sound wave propagation of the discharge noises have been simulated using two-dimensional FDTD method to examine the effect of insulator shape on the observed waveform. In the course of the study, the shape data of the insulator was expressed as the set of elements that typify the media (air and solid), directions of air-solid (porcelain) boundary, and directions of ‘Free Space’ boundary by allocating the colors on the corresponding bitmap image file. The source points of the sound were also arranged into the bitmap. Calculated wave propagation for each time step is again expressed in the form of bitmap for visualization. The nature of the calculated sound waveforms for different insulator shapes and discharge positions are compared with that in the experiment.

  20. On the motion of inertial particles by sound waves

    Science.gov (United States)

    Cleckler, Jay; Elghobashi, Said; Liu, Feng

    2012-03-01

    This paper describes the numerical simulation of the motion of a heavy spherical particle in an acoustic wave using the equation of motion for a point particle. Our results agree well with the recent experimental data of Gonzàlez, Hoffmann, and Gallego ["Precise measurements of particle entrainment in a standing-wave acoustic field between 20 and 3500 Hz," J. Aerosol Sci. 31, 1461-1468 (2000)]. Our simulations cover a range of particle relaxation number, τ* = ωτ, where τ is the particle relaxation time and ω is the angular acoustic frequency from 0.06 to 10, particle to fluid density ratios, ρp/ρf, from 2500 to 2, and moderate acoustic velocity amplitudes. The results show that the Stokes force controls particle motion for τ* 25. Within this regime it is appropriate to consider the Basset, pressure gradient, and virtual mass forces as "higher order" corrections to the Stokes force. The magnitude of the Basset force exceeds that of the Stokes force for ρp/ρf ⩾ 25 and τ* ⩾ 4. All the forces in the particle equation of motion should be accounted for when simulating particle motion in an acoustic wave for ρp/ρf < 25.

  1. Use of the oblique ionospheric sounding data for detection internal gravity waves in bottom thermosphere

    Science.gov (United States)

    Bochkarev, V.; Petrova, I.; Teplov, V.

    The opportunity of use of the oblique ionospheric sounding data for study Internal Gravity Waves at heights of 80-150 kms is discussed in this report. The moving of electronic concentration inhomogeneities caused by passage of Internal Gravity Waves, is resulted in variations of radiowave parameters, such as angle of arrival, phase and Doppler shift of frequency. It is necessary to distinguish variations caused to passages of Internal Gravity Waves from variations caused by other reasons (interference of modes, turbulent scattering etc.). For this purpose the modelling estimations and information on properties of Internal Gravity Waves are used. The period of Internal Gravity Waves depends on Brant- Vaisala's frequency, which is determined by size of a density gradient , and angle between a vector of phase speed and vertical line. The Brant-Vaisala's frequency changes a little (and slowly), therefore angle of a wave vector with a vertical line can be estimated on the period of these variations. Inhomo geneities, which are oriented along a radio beam, do not cause changes of vertical arrival angle. Inhomogeneities, which are oriented across a radio beam, cause fluctuation angle of elevation and horizontal angle. Thus, the amplitudes and phases of Doppler shift variations of frequency and angle of arrival allow to define a direction of propagation of Internal Gravity Waves . The oblique ionospheric sounding experiment in a short-wave region was carried out in the autumn of 2001. The monitoring was carried out by a passive 4-channel complex for measurements of corners and phases with small base. As a result of processing measurements the periodic variations of parameters of an oblique sounding signal which can be interpreted as caused by propagation of Internal Gravity Waves.

  2. Sound waves induce Volkov-like states, band structure and collimation effect in graphene.

    Science.gov (United States)

    Oliva-Leyva, M; Naumis, Gerardo G

    2016-01-20

    We find exact states of graphene quasiparticles under a time-dependent deformation (sound wave), whose propagation velocity is smaller than the Fermi velocity. To solve the corresponding effective Dirac equation, we adapt the Volkov-like solutions for relativistic fermions in a medium under a plane electromagnetic wave. The corresponding electron-deformation quasiparticle spectrum is determined by the solutions of a Mathieu equation resulting in band tongues warped in the surface of the Dirac cones. This leads to a collimation effect of electron conduction due to strain waves.

  3. 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.

  4. Dynamics of Langmuir and ion-sound waves in type III solar radio sources

    Science.gov (United States)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The study traces the evolution of Langmuir and ion-sound waves in type III sources, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. It is shown that the conditions in the solar wind do not allow a steady state to be attained; instead, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be rapid enough to saturate the growth of the parent Langmuir waves in the available interaction time. The competing processes of nonlinear wave collapse and quasi-linear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth.

  5. 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.

  6. Analysis of sound propagation in ducts using the wave envelope concept

    Science.gov (United States)

    Baumeister, K. J.

    1974-01-01

    A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow for plane wave input. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution does not oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude, and the number of grid points becomes independent of the sound frequency. Physically, the transformed pressure represents the amplitude of the conventional sound wave. Example solutions are presented for sound propagation in a one-dimensional straight hard-wall duct and in a two-dimensional straight soft-wall duct without steady flow. The numerical solutions show evidence of the existence along the duct wall of a developing acoustic pressure diffusion boundary layer which is similar in nature to the conventional viscous flow boundary layer. In order to better illustrate this concept, the wave equation and boundary conditions are written such that the frequency no longer appears explicitly in them. The frequency effects in duct propagation can be visualized solely as an expansion and stretching of the suppressor duct.

  7. 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...... 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...... 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...

  8. Sound

    CERN Document Server

    2013-01-01

    Sound has the power to soothe, excite, warn, protect, and inform. Indeed, the transmission and reception of audio signals pervade our daily lives. Readers will examine the mechanics and properties of sound and provides an overview of the "interdisciplinary science called acoustics." Also covered are functions and diseases of the human ear.

  9. Sound wave energy emitted by water drop during the splash on the soil surface

    Science.gov (United States)

    Bieganowski, Andrzej; Ryżak, Magdalena; Korbiel, Tomasz

    2017-04-01

    A drop of rain falling on the surface of bare soil not only moisturizes but also can cause splash or compaction, depending on the energy of incident drops and the condition of the surface on which it falls. The splash phenomenon can be characterized by the weight of detached soil material (using splash cups) as well as the number and trajectory of splashed particles (using high-speed cameras). The study presents a new aspect of the analysis of the splash phenomenon by measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out in an anechoic chamber. Three soils (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) were tested. Drops of 4.2 mm diameter were falling from a height of 1.5m. The sound pressure level was recorded after 10 consecutive water drop impacts using a special set of microphones. In all measuring conditions with 1m distance, the sound pressure level ranged from 27 to 42dB. The impact of water drops on the ground created sound pulses, which were recalculated to the energy emitted in the form of sound waves. For all soil samples, the sound wave energy was within the range of 0.14 μJ to 5.26 μJ, which corresponds to 0.03-1.07% of the energy of the incident drops (Ryżak et al., 2016). This work was partly financed from the National Science Centre, Poland; project no. 2014/14/E/ST10/00851. References Ryżak M., Bieganowski A., Korbiel T.: Sound wave Energy resulting from the impact of water drops on the soil surface. PLoS One 11(7):e0158472. doi:10.1371/journal.pone.0158472, 2016

  10. Nonlinear Alfvén, magnetosonic, sound, and electron inertial waves in fluid formalism

    Science.gov (United States)

    Stasiewicz, K.

    2005-03-01

    A fluid model of nonlinear electron and ion inertial waves in anisotropic plasmas is presented. The model has been verified for plasma beta (ratio of kinetic/magnetic pressures) in a range between 0.1 and 15. It is shown that warm plasmas support four types of nonlinear waves, which correspond to four linear modes, Alfvénic, magnetosonic, sound, and electron inertial waves. Each of these nonlinear modes has slow and fast versions. Modes slower than the sound speed have left-handed polarization for the transverse magnetic field, while the faster modes have right-handed polarization. It is shown by direct integration that the exponential growth rate of nonlinear modes is balanced by the ion and electron dispersion leading to solutions in the form of trains of solitons or cnoidal waves. By using a novel technique of phase portraits, it is shown how the dispersive properties of electron and ion inertial waves change at the transition between warm and hot plasmas (β ≈ 1) and how trains of solitons ("mirror modes") are produced in a hot, anisotropic plasma. The applicability of the model is illustrated by showing that the electric currents carried by nonlinear waves measured on Cluster spacecraft in the magnetosheath at β ≈ 15 are well reproduced by currents derived from the theoretical model.

  11. Understanding the gravitational-wave Hellings and Downs curve for pulsar timing arrays in terms of sound and electromagnetic waves

    Science.gov (United States)

    Jenet, Fredrick A.; Romano, Joseph D.

    2015-07-01

    Searches for stochastic gravitational-wave backgrounds using pulsar timing arrays look for correlations in the timing residuals induced by the background across the pulsars in the array. The correlation signature of an isotropic, unpolarized gravitational-wave background predicted by general relativity follows the so-called Hellings and Downs curve, which is a relatively simple function of the angle between a pair of Earth-pulsar baselines. In this paper, we give a pedagogical discussion of the Hellings and Downs curve for pulsar timing arrays, considering simpler analogous scenarios involving sound and electromagnetic waves. We calculate Hellings-and-Downs-type functions for these two scenarios and develop a framework suitable for doing more general correlation calculations.

  12. Sounding-Rocket Studies of Langmuir-Wave Microphysics in the Auroral Ionosphere

    Science.gov (United States)

    Dombrowski, Micah P.

    Since their discovery in laboratory plasmas in the 1920s, Langmuir waves have been observed to be ubiquitous in plasma environments, particularly in space plasmas. From the greater solar wind to planetary foreshocks and the auroral ionosphere, Langmuir waves are a key factor mediating electron temperature, and controlling electron beam propagation and beam-plasma energy transfer. Because they are so important, Langmuir waves in the space environment have been intensively investigated; however, there remain two challenging types of experiments that are relatively lacking: three-dimensional measurements of Langmuir-wave fields, and measurements of Langmuir wave-electron correlations. This thesis works on filling these two gaps, plus development of new Langmuir-wave instrumentation. The CHARM-II wave-particle Correlator instrument was designed to study the energy transfer between electron beams and plasmas via the sorting of incoming particles by concurrent Langmuir-wave phase, allowing for direct observation of electron bunching. Data from the CHARM-II sounding rocket comprises the first such observations with statistical levels of events, revealing an association between the polarity of the resistive component of the electron phase-bunching and changes in the electron flux at the associated energy, such that a negative resistive component goes with an increase in electron flux, and vice versa, effectively showing energy flow from the beam to the waves, and subsequent enhancements of wave damping. Surprisingly, the results also show comparable amounts of resistive and reactive activity. A test-particle simulation was developed to confirm the details of the theoretical explanation for the observed effect. A three-dimensional Langmuir-wave receiver flown on the TRICE sounding rocket mission reveals the beat signature of the amplitude-modulated 'bursty' form of Langmuir waves which has been observed in many environments. An analysis of the three-dimensional data shows

  13. Measured and calculated transmission losses of sound waves through a helium layer

    Science.gov (United States)

    Norum, T. D.

    1973-01-01

    An experiment was performed to measure the transmission losses of sound waves traversing an impedance layer. The sound emanated from a point source and the impedance layer was created by a low-speed helium jet. The transmission losses measured were of the order of 12 db for frequencies of the source between 4 and 12 kHz. These losses are greater than those predicted from analysis when the observer angle is less than about 35 deg, but less than those predicted for larger observer angles. The experimental results indicate that appreciable noise reductions can be realized for an observer shielded by an impedance layer, irrespective of his position relative to the source of sound.

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

    DEFF Research Database (Denmark)

    Müller, Robert; Häfner, Stephan; Dupleich, Diego

    2016-01-01

    and verification of those novel technologies required an understanding of the propagation effects at mm-Wave which enabled by channel sounding measurements and analysis. Due to the variety of considered frequency bands and the necessity of spatial resolved measurements for e.g. testing of beamforming approaches......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......, which comprises the microwave band at 10 GHz and the mm-Wave band at 30 GHz. Preliminary analysis results are presented....

  15. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device.

    Science.gov (United States)

    Heywood, Sarah L; Glavin, Boris A; Beardsley, Ryan P; Akimov, Andrey V; Carr, Michael W; Norman, James; Norton, Philip C; Prime, Brian; Priestley, Nigel; Kent, Anthony J

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1-12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  16. Sound radiation from an infinite elastic cylinder with dual-wave propagation-intensity distributions

    Science.gov (United States)

    Fuller, C. R.

    1988-01-01

    The radiation of sound from an elastic cylindrical shell filled with fluid and supporting multiwave propagation is studied analytically. Combinations of supersonic and subsonic shell waves are considered. The radiated field is mapped by using acoustic intensity vectors evaluated at various locations. Both time averaged and instantaneous intensity are investigated. The acoustic intensity is seen to vary markedly with axial distance down the cylinder. The effect is shown to be associated with cross terms in the intensity relations, and its magnitude and location to depend upon the relative phase and amplitudes of individual waves. Subsonic shell waves are demonstrated to interact strongly with supersonic shell waves to cause a large modification in the radiated intensity distributions near the shell surface.

  17. The electric response in the wave of second sound: Hardware aspect

    Science.gov (United States)

    Rybalko, A. S.; Chagovets, T. V.; Korolev, A. M.

    2017-06-01

    A detailed description of the standard measuring techniques and original technical solutions used by the authors while studying the recently discovered phenomenon of electric response in the second sound wave. The most successful amplifier circuits used for precision low-temperature measurements are presented, as well as a sensitivity analysis of the different measuring systems. The main goal of the study is to substantiate the reliability of the electrical activity effect occurring in a resonator with He II when a second sound wave is excited. It is shown that the observed electric response signal is not associated with external interference or internal pick-ups, and is also not the result of either direct acoustoelectric conversion or thermal contact potentials. An analysis and comparison of new experimental data obtained by two scientific groups is also presented.

  18. Ion sound and dust acoustic waves at finite size of plasma particles

    CERN Document Server

    Andreev, Pavel A

    2014-01-01

    We consider influence of finite size of ions on properties of classic plasmas. We focus our attention on the ion sound for electron-ion plasmas. We also consider dusty plasmas, where we account finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. Finite size of particles affects classical plasma properties. Finite size of particles gives considerable contribution for small wave lengths, which is area of appearing of quantum effects. Consequently, it is very important to consider finite size of ions in quantum plasmas as well.

  19. The Impact of Sound on Electroencephalographic Waves during Sleep in Patients Suffering from Tinnitus

    Directory of Open Access Journals (Sweden)

    Marisa Pedemonte

    2014-09-01

    The main results found were that the largest number of changes, considering both the power spectrum and wave׳s coherence, occurred in stages N2 and N3. The delta and theta bands were the most changed, with important changes also in coherence of spindles during N2. All changes were more frequent in temporal areas. The differences between the two hemispheres do not depend, at least exclusively, on the side where the tinnitus is perceived and, hence, of the stimulated side. These results demonstrate that sound stimulation during sleep in tinnitus patients׳ influences brain activity and open an avenue for investigating the mechanism underlying tinnitus and its treatment.

  20. Development of a hybrid wave based-transfer matrix model for sound transmission analysis.

    Science.gov (United States)

    Dijckmans, A; Vermeir, G

    2013-04-01

    In this paper, a hybrid wave based-transfer matrix model is presented that allows for the investigation of the sound transmission through finite multilayered structures placed between two reverberant rooms. The multilayered structure may consist of an arbitrary configuration of fluid, elastic, or poro-elastic layers. The field variables (structural displacements and sound pressures) are expanded in terms of structural and acoustic wave functions. The boundary and continuity conditions in the rooms determine the participation factors in the pressure expansions. The displacement of the multilayered structure is determined by the mechanical impedance matrix, which gives a relation between the pressures and transverse displacements at both sides of the structure. The elements of this matrix are calculated with the transfer matrix method. First, the hybrid model is numerically validated. Next a comparison is made with sound transmission loss measurements of a hollow brick wall and a sandwich panel. Finally, numerical simulations show the influence of structural damping, room dimensions and plate dimensions on the sound transmission loss of multilayered structures.

  1. A Discrete Constraint for Entropy Conservation and Sound Waves in Cloud-Resolving Modeling

    Science.gov (United States)

    Zeng, Xi-Ping; Tao, Wei-Kuo; Simpson, Joanne

    2003-01-01

    Ideal cloud-resolving models contain little-accumulative errors. When their domain is so large that synoptic large-scale circulations are accommodated, they can be used for the simulation of the interaction between convective clouds and the large-scale circulations. This paper sets up a framework for the models, using moist entropy as a prognostic variable and employing conservative numerical schemes. The models possess no accumulative errors of thermodynamic variables when they comply with a discrete constraint on entropy conservation and sound waves. Alternatively speaking, the discrete constraint is related to the correct representation of the large-scale convergence and advection of moist entropy. Since air density is involved in entropy conservation and sound waves, the challenge is how to compute sound waves efficiently under the constraint. To address the challenge, a compensation method is introduced on the basis of a reference isothermal atmosphere whose governing equations are solved analytically. Stability analysis and numerical experiments show that the method allows the models to integrate efficiently with a large time step.

  2. Is there really a sound line limit for surface waves in phononic crystals?

    Science.gov (United States)

    Benchabane, Sarah; Khelif, Abdelkrim; Laude, Vincent

    2011-03-01

    When phononic crystal were first introduced in the early 1990's, their ability to prohibit acoustic wave propagation was first demonstrated for bulk waves. Since then, it has been shown that these artificial materials offer unprecedented ways of steering the course of any type of elastic waves, bulk or guided. A series of works has then focused on investigating the effects these artificial materials could have on already confined surface-guided waves, an interest clearly driven by the prominent position surface acoustic waves and their combination with piezoelectric solids occupy in the vast field of wireless telecommunication systems. Theoretical reports stated that complete surface wave band gaps could be obtained in perfect 2D structures. Experimental demonstrations did not live up to one's expectations, though: significant energy loss was observed for frequencies supposedly lying above the bandgap and coupling of the acoustic energy to the bulk substrate was blamed. The radiation of these modes located above a sound line - defined by the dispersion relation of the bulk mode with the lowest velocity - seemed to cast a genuine stumbling block on the development of phononic structures relying on surface waves. Yet, if losses are unavoidable there, configurations do exist that can make them acceptable. In this paper, we will focus more closely on recent theoretical and experimental results that show, through the simulation, fabrication and characterization of a hypersonic phononic crystal, not only that bandgaps can be obtained at near-GHz frequencies, but also that a clear transmission of the signal can be observed even for modes lying within the sound cone.

  3. Sound waves effectively assist tobramycin in elimination of Pseudomonas aeruginosa biofilms in vitro.

    Science.gov (United States)

    Bandara, H M H N; Harb, A; Kolacny, D; Martins, P; Smyth, H D C

    2014-12-01

    Microbial biofilms are highly refractory to antimicrobials. The aim of this study was to investigate the use of low-frequency vibration therapy (20-20 kHz) on antibiotic-mediated Pseudomonas aeruginosa biofilm eradication. In screening studies, low-frequency vibrations were applied on model biofilm compositions to identify conditions in which surface standing waves were observed. Alginate surface tension and viscosity were also measured. The effect of vibration on P. aeruginosa biofilms was studied using a standard biofilm assay. Subminimal inhibitory concentrations (sub-MIC) of tobramycin (5 μg/ml) were added to biofilms 3 h prior, during, and immediately after vibration and quantitatively assessed by (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) reduction assay (XTT) and, qualitatively, by confocal laser scanning microscopy (CLSM). The standing waves occurred at frequencies sound waves together with antibiotics are a promising approach in eliminating pathogenic biofilms.

  4. [Echolocation sound waves, morphological features and foraging strategies in Hipposideros pratti].

    Science.gov (United States)

    Chen, Min; Feng, Jiang; Li, Zhenxin; Zhou, Jiang; Zhao, Huihua; Zhang, Shuyi; Sheng, Lianxi

    2002-12-01

    Studies on the echolocation sound waves in different states (flying and hanging), morphological features and ecological processes (foraging strategies, foraging habitat and diet type) of Hipposideros pratti showed that H. pratti had CF (constant frequency)-FM (frequency modulated) echolocation sounds. There were some differences in dominant frequency (caused by Doppler compensating effect), pulse repetition rate, pulse duration and interpulse interval between the bats at flying and hanging. The dominant frequency, FM bandwidth, pulse duration and interpulse interval were lower, while the pulse repetition rate and duty cycle were higher at flying than at hanging. All the differences indicated that H. pratti could adopt specific echolocation sounds to adapt to specific environments and conditions to detect, approach and capture their preys successfully. On the basis of echolocation sound and field observation, it was concluded that H. pratti might search the preys at flying in the period of insect fastigium, and after the period, it might search the targets at hanging. The foraging habitat was near the tree crowns, and the preys consisted mainly of relatively large insects, such as beetles.

  5. 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

    A method of estimating the sound field radiated by a source under non-anechoic conditions has been examined. The method uses near field acoustic holography based on a combination of pressure and particle velocity measurements in a plane near the source for separating outgoing and ingoing wave...... components. The outgoing part of the sound field is composed of both radiated and scattered waves. The method compensates for the scattered components of the outgoing field on the basis of the boundary condition of the problem, exploiting the fact that the sound field is reconstructed very close...... 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....

  6. Optimal digital filtering versus difference waves on the mismatch negativity in an uninterrupted sound paradigm.

    Science.gov (United States)

    Kalyakin, Igor; Gonzalez, Narciso; Joutsensalo, Jyrki; Huttunen, Tiina; Kaartinen, Jukka; Lyytinen, Heikki

    2007-01-01

    Conventionally, mismatch negativity (MMN) is analyzed through the calculation of the difference waves. This helps to eliminate some exogenous event-related potential (ERP) components. However, this reduces the signal-to-noise ratio (SNR). This study aims to test whether or not the optimal digital filtering performs better than the difference waves procedure in quantitative ERP analyses in an uninterrupted sound paradigm. The participants were 102 children aged 8-16 years. The MMN was elicited in a passive oddball paradigm presenting an uninterrupted sound consisting of two alternating tones (600 and 800 Hz) of the same duration (100 msec) with infrequent shortenings of one of the 600 Hz tones (50 or 30 msec). In the grand average, both the 50 and 30 msec tones showed a clear MMN-like activity. Each 100 msec tone elicited some rhythmic activity with relatively consistent ERP waveforms. The difference waves calculated from the offset of the deviant stimuli (time correction due to shortening of the deviant stimuli) failed to separate the MMN from this activity, and produced spurious ERPs at early latencies. The optimal digital filtering freed the MMN from this rhythmic activity, improved the SNR, and thus stabilized the quantitative amplitude and latency analyses of the MMN. The frequency range for optimal extraction of the MMN in this paradigm was 2-8.5 Hz.

  7. Radiative amplification of sound waves in the winds of O and B stars

    Science.gov (United States)

    Macgregor, K. B.; Hartmann, L.; Raymond, J. C.

    1979-01-01

    The velocity perturbation associated with an outwardly propagating sound wave in a radiation-driven stellar wind gives rise to a periodic Doppler shifting of absorption lines formed in the flow. A linearized theory applicable to optically thin waves is used to show that the resulting fluctuation in the absorption-line force can cause the wave amplitude to grow. Detailed calculations of the acceleration due to a large number of lines indicate that significant amplification can occur throughout the high-velocity portion of winds in which the dominant force-producing lines have appreciable optical depths. In the particular case of the wind of Zeta Pup (O4f), it is found that the e-folding distance for wave growth is considerably shorter than the scale lengths over which the physical properties of the flow vary. A qualitative estimate of the rate at which mechanical energy due to nonlinear waves can be dissipated suggests that this mechanism may be important in heating the supersonic portion of winds of early-type stars.

  8. Hybrid Resonant Acoustics: Exploiting a New Class of Sound Waves for Highly Efficient Microfluidic Nebulisation

    Science.gov (United States)

    Rezk, Amgad; Yeo, Leslie

    2017-11-01

    A longstanding convention in acoustomicrofluidic manipulation-a consequence of wholesale adoption from decades long application of surface acoustic waves (SAWs) in electronics and telecommunications-has been to employ pure SAWs by eliminating wave reflections and bulk resonances in single crystal piezoelectric substrates with the assumption that this provides the most efficient way to actuate or manipulate fluid flow at microscale dimensions. Despite the many advantages of SAW microfluidics, particularly for aerosolising and hence delivering next generation macromolecular-based therapeutics via inhalation, the limitation of the SAW devices, however, lies in the input power it can sustain, thus constraining the nebulisation rates that can be generated, which has, among other things, severely hampered its practical adoption in pulmonary drug administration to date. Here, we unravel the existence of a surface reflected bulk wave (SRBW)-the first new class of sound waves to have been discovered in well over five decades-and show, quite counterintuitively, that it is possible to obtain an order-of-magnitude improvement in microfluidic manipulation efficiency through this unique hybrid combination of surface and bulk waves without increasing complexity or cost.

  9. 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.

  10. On Peculiarities of Radio Wave Scattering by a Sound Pulse in the Atmosphere

    Science.gov (United States)

    Bryukhovetski, A. S.; Vichkan', A. V.

    2016-03-01

    Purpose: Scattering of radio waves by a sound pulse in the atmosphere is investigated theoretically. Design/methodology/approach: The asymptotic of the scattered field in the approximation of the Fresnel diffraction is analyzed using the quadratic expansion of the phase and Gaussian directional patterns of radiating systems. Findings: It is shown that for small angles of backscattering the field is determined by the focusing effects. Conclusions: Explanation of the focus by “degenerate” saddle points of the studied integrand phase is suggested.

  11. 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...... sound sources from the stage and the PA system were recorded, as well as the audience noise, and impulse responses of the concert venue. The audience noise was implemented in the production phase. A comparative study compared an experience with and without audience noise. In a between subject experiment...

  12. Observation of standing waves of electron-hole sound in a photoexcited semiconductor.

    Science.gov (United States)

    Padmanabhan, P; Young, S M; Henstridge, M; Bhowmick, S; Bhattacharya, P K; Merlin, R

    2014-07-11

    Three-dimensional multicomponent plasmas composed of species with very different masses support a new branch of charge-density fluctuations known as acoustic plasmons. Here, we report on an ultrafast optical method to generate and probe coherent states of acoustic plasmons in a slab of GaAs, which relies on strong photoexcitation to create a large population of light electrons and heavy holes. Consistent with the random-phase-approximation theory, the data reveal standing plasma waves confined to these slabs, similar to those of conventional sound but with associated velocities that are significantly larger.

  13. Surface refraction of sound waves affects calibration of three-dimensional ultrasound.

    Science.gov (United States)

    Ballhausen, Hendrik; Ballhausen, Bianca Désirée; Lachaine, Martin; Li, Minglun; Parodi, Katia; Belka, Claus; Reiner, Michael

    2015-05-27

    Three-dimensional ultrasound (3D-US) is used in planning and treatment during external beam radiotherapy. The accuracy of the technique depends not only on the achievable image quality in clinical routine, but also on technical limitations of achievable precision during calibration. Refraction of ultrasound waves is a known source for geometric distortion, but such an effect was not expected in homogenous calibration phantoms. However, in this paper we demonstrate that the discontinuity of the refraction index at the phantom surface may affect the calibration unless the ultrasound probe is perfectly perpendicular to the phantom. A calibration phantom was repeatedly scanned with a 3D-US system (Elekta Clarity) by three independent observers. The ultrasound probe was moved horizontally at a fixed angle in the sagittal plane. The resulting wedge shaped volume between probe and phantom was filled with water to couple in the ultrasound waves. Because the speed of sound in water was smaller than the speed of sound in Zerdine, the main component of the phantom, the angle of the ultrasound waves inside the phantom increased. This caused an apparent shift in the calibration features which was recorded as a function of the impeding angle. To confirm the magnitude and temperature dependence, the experiment was repeated by two of the observers with a mixture of ice and water at 0 °C and with thermalized tap water at 21 °C room temperature. During the first series of measurements, a linear dependency of the displacements dx of the calibration features on the angle α of the ultrasound probe was observed. The three observers recorded significantly nonzero (p sound of 1,402 m/s at the melting point of ice. At 21 °C, slopes of 0.11 and 0.12 mm/° were recorded in agreement with the first experiment at about room temperature. The difference to the theoretical expectation of 0.07 mm/° was not significant (p = 0.09). The surface refraction of sound waves my affect the

  14. Ultrawideband VNA Based Channel Sounding System for Centimetre and Millimetre Wave Bands

    DEFF Research Database (Denmark)

    Hejselbæk, Johannes; Fan, Wei; Pedersen, Gert F.

    2016-01-01

    Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations of an exi......Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations...... of an existing vector network analyzer (VNA) based channel sounding system in terms of frequency range and measurement range. After that, an improved system is proposed to address these limitations. The proposed system is capable of measuring from 2 to 50 GHz at 30 meters distances. A measurement campaign...

  15. 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.

  16. Observationally constrained modeling of sound in curved ocean internal waves: examination of deep ducting and surface ducting at short range.

    Science.gov (United States)

    Duda, Timothy F; Lin, Ying-Tsong; Reeder, D Benjamin

    2011-09-01

    A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the shelf of the South China Sea northeast of Tung-Sha Island. Construction of the time-varying three-dimensional sound-speed fields used in the modeling simulations was guided by environmental data collected concurrently with the acoustic data. Computed three-dimensional propagation results compare well with field observations. The simulations allow identification of time-dependent sound forward scattering and ducting processes within the curved internal gravity waves. Strong acoustic intensity enhancement was observed during passage of high-amplitude nonlinear waves over the source/receiver paths, and is replicated in the model. The waves were typical of the region (35 m vertical displacement). Two types of ducting are found in the model, which occur asynchronously. One type is three-dimensional modal trapping in deep ducts within the wave crests (shallow thermocline zones). The second type is surface ducting within the wave troughs (deep thermocline zones). © 2011 Acoustical Society of America

  17. 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.

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

    Science.gov (United States)

    Zeng, Liang; Smith, Chris; Poelzer, G. Herold; Rodriguez, Jennifer; Corpuz, Edgar; Yanev, George

    2014-12-01

    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.

  19. Reconstruction of nonstationary sound fields based on the time domain plane wave superposition method.

    Science.gov (United States)

    Zhang, Xiao-Zheng; Thomas, Jean-Hugh; Bi, Chuan-Xing; Pascal, Jean-Claude

    2012-10-01

    A time-domain plane wave superposition method is proposed to reconstruct nonstationary sound fields. In this method, the sound field is expressed as a superposition of time convolutions between the estimated time-wavenumber spectrum of the sound pressure on a virtual source plane and the time-domain propagation kernel at each wavenumber. By discretizing the time convolutions directly, the reconstruction can be carried out iteratively in the time domain, thus providing the advantage of continuously reconstructing time-dependent pressure signals. In the reconstruction process, the Tikhonov regularization is introduced at each time step to obtain a relevant estimate of the time-wavenumber spectrum on the virtual source plane. Because the double infinite integral of the two-dimensional spatial Fourier transform is discretized directly in the wavenumber domain in the proposed method, it does not need to perform the two-dimensional spatial fast Fourier transform that is generally used in time domain holography and real-time near-field acoustic holography, and therefore it avoids some errors associated with the two-dimensional spatial fast Fourier transform in theory and makes possible to use an irregular microphone array. The feasibility of the proposed method is demonstrated by numerical simulations and an experiment with two speakers.

  20. Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II

    Science.gov (United States)

    Turner, T. N.

    1983-01-01

    A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.

  1. 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.

  2. A comparison between directly measured and inferred wave speeds from an acoustic propagation experiment in Currituck Sound.

    Science.gov (United States)

    Ballard, Megan S; Costley, R Daniel; Sagers, Jason D; Lee, Kevin M; McNeese, Andrew R; Hathaway, Kent K; Wilson, Preston S; Smith, Eric W

    2018-01-01

    An acoustic propagation experiment was conducted in Currituck Sound to characterize low-frequency propagation in a very-shallow-water estuarine environment. The water column properties were homogeneous over the study area, and the emphasis of this work is on understanding the propagation effects induced by the estuarine bed. During the experiment, low-frequency sound propagation measurements of waterborne sound and interface waves were acquired, and direct measurements of the compressional and shear wave properties were obtained at high frequencies. The propagation data consist of signals from a Combustive Sound Source recorded on bottom mounted geophones and a vertical line array of hydrophones. A statistical inference method was applied to obtain an estimate of the sediment compressional and shear wave speed profiles as a function of depth within the estuarine bed. The direct measurements were obtained in situ by inserting probes 30 cm into the sediment. Sediment acoustics models were fit to the high-frequency in situ data to enable comparison with the inferred low-frequency wave speeds. Overall, good agreement was found between the directly measured and inferred wave speeds for both the compressional and shear wave data.

  3. Classification of biological cells using a sound wave based flow cytometer

    Science.gov (United States)

    Strohm, Eric M.; Gnyawali, Vaskar; Van De Vondervoort, Mia; Daghighi, Yasaman; Tsai, Scott S. H.; Kolios, Michael C.

    2016-03-01

    A flow cytometer that uses sound waves to determine the size of biological cells is presented. In this system, a microfluidic device made of polydimethylsiloxane (PDMS) was developed to hydrodynamically flow focus cells in a single file through a target area. Integrated into the microfluidic device was an ultrasound transducer with a 375 MHz center frequency, aligned opposite the transducer was a pulsed 532 nm laser focused into the device by a 10x objective. Each passing cell was insonfied with a high frequency ultrasound pulse, and irradiated with the laser. The resulting ultrasound and photoacoustic waves from each cell were analyzed using signal processing methods, where features in the power spectra were compared to theoretical models to calculate the cell size. Two cell lines with different size distributions were used to test the system: acute myeloid leukemia cells (AML) and melanoma cells. Over 200 cells were measured using this system. The average calculated diameter of the AML cells was 10.4 +/- 2.5 μm using ultrasound, and 11.4 +/- 2.3 μm using photoacoustics. The average diameter of the melanoma cells was 16.2 +/- 2.9 μm using ultrasound, and 18.9 +/- 3.5 μm using photoacoustics. The cell sizes calculated using ultrasound and photoacoustic methods agreed with measurements using a Coulter Counter, where the AML cells were 9.8 +/- 1.8 μm and the melanoma cells were 16.0 +/- 2.5 μm. These results demonstrate a high speed method of assessing cell size using sound waves, which is an alternative method to traditional flow cytometry techniques.

  4. Long-Term Change of Sound Wave Propagation Attenuation Due to the Effects of Ocean Acidification

    Science.gov (United States)

    Gotoh, S.; Tsuchiya, T.; Hiyoshi, Y.

    2014-12-01

    In recent years, the concentration of carbon dioxide in the atmosphere is increasing due to global warming. And, the ocean acidification advances because this melts into seawater, pH decrease in seawater are concerned. The sound wave to propagate seawater, pH is known to affect absorption loss (α) by chemical buffer effects of the seawater. However, conventionally, α has not been investigated much in the calculation of pH. Therefore, when calculating the propagation distance in the sonar equation, pH =8~8.1 (Weak alkaline) are used empirically. Therefore we used an actual value of pH of 30 years from 1984 in the sea near the Japan, and investigated change over the years of absorption loss (α) at some frequency. As a result, we found that α value decreases gradually in the past 30 years, as high-latitude decreases. Further, the future, assuming that ocean acidification is more advanced, and to simulate a change of the absorption loss and propagation loss in end of this century using the pH value reported from the "Intergovernmental Panel on Climate Change" (IPCC). As a result, it was just suggested that α decreased more in the end of this century and affected the submarine detection. In addition, in recent years, we examined the effects of noise that offshore wind power construction proceeds in each country emits gives to the underwater sound. As a result, in the end of this century, an underwater noise increases about 17%, and underwater sound environmental degradation of the sea is concerned.

  5. Three-in-one resonance tube for harmonic series sound wave experiments

    Science.gov (United States)

    Jaafar, Rosly; Nazihah Mat Daud, Anis; Ali, Shaharudin; Kadri Ayop, Shahrul

    2017-07-01

    In this study we constructed a special three-in-one resonance tube for a harmonic series sound waves experiment. It is designed for three different experiments: both-open-end, one-closed-end and both-closed-end tubes. The resonance tube consists of a PVC conduit with a rectangular hole, rubber tube, plastic stopper with an embedded microphone and a plastic stopper. The resonance tube is utilized with visual analyser freeware to detect, display and measure the resonance frequencies for each harmonic series. The speeds of sound in air, v, are determined from the gradient of the 2(L+e) versus n fn-1 , 4(L+e) versus n fn-1 and 2L versus n fn-1 graphs for both-open-end, one-closed-end and both-closed-end tubes, respectively. The compatibility of a resonance tube for a harmonic series experiment is determined by comparing the experimental and standard values of v. The use of a resonance tube produces accurate results for v within a 1.91% error compared to its standard value. It can also be used to determine the values of end correction, e, in both-open-end and one-closed-end tubes. The special resonance tube can also be used for the values of n for a harmonic series experiment in the three types of resonance tubes: both-open-end, one-closed-end and both-closed-end tubes.

  6. Wideband characterization of the complex wave number and characteristic impedance of sound absorbers.

    Science.gov (United States)

    Salissou, Yacoubou; Panneton, Raymond

    2010-11-01

    Several methods for measuring the complex wave number and the characteristic impedance of sound absorbers have been proposed in the literature. These methods can be classified into single frequency and wideband methods. In this paper, the main existing methods are revisited and discussed. An alternative method which is not well known or discussed in the literature while exhibiting great potential is also discussed. This method is essentially an improvement of the wideband method described by Iwase et al., rewritten so that the setup is more ISO 10534-2 standard-compliant. Glass wool, melamine foam and acoustical/thermal insulator wool are used to compare the main existing wideband non-iterative methods with this alternative method. It is found that, in the middle and high frequency ranges the alternative method yields results that are comparable in accuracy to the classical two-cavity method and the four-microphone transfer-matrix method. However, in the low frequency range, the alternative method appears to be more accurate than the other methods, especially when measuring the complex wave number.

  7. A wave-envelope of sound propagation in nonuniform circular ducts with compressible mean flows

    Science.gov (United States)

    Nayfeh, A. H.; Kaiser, J. E.; Shaker, B. S.

    1979-01-01

    An acoustic theory is developed to determine the sound transmission and attenuation through an infinite, hard-walled or lined circular duct carrying compressible, sheared, mean flows and having a variable cross section. The theory is applicable to large as well as small axial variations, as long as the mean flow does not separate. The technique is based on solving for the envelopes of the quasi-parallel acoustic modes that exist in the duct instead of solving for the actual wave, thereby reducing the computation time and the round-off error encountered in purely numerical techniques. The solution recovers the solution based on the method of multiple scales for slowly varying duct geometry. A computer program was developed based on the wave-envelope analysis for general mean flows. Results are presented for the reflection and transmission coefficients as well as the acoustic pressure distributions for a number of conditions: both straight and variable area ducts with and without liners and mean flows from very low to high subsonic speeds are considered.

  8. Plane waves at or near grazing incidence in the parabolic approximation. [acoustic equations of motion for sound fields

    Science.gov (United States)

    Mcaninch, G. L.; Myers, M. K.

    1980-01-01

    The parabolic approximation for the acoustic equations of motion is applied to the study of the sound field generated by a plane wave at or near grazing incidence to a finite impedance boundary. It is shown how this approximation accounts for effects neglected in the usual plane wave reflection analysis which, at grazing incidence, erroneously predicts complete cancellation of the incident field by the reflected field. Examples are presented which illustrate that the solution obtained by the parabolic approximation contains several of the physical phenomena known to occur in wave propagation near an absorbing boundary.

  9. Sound wave propagation on the human skull surface with bone conduction stimulation.

    Science.gov (United States)

    Dobrev, Ivo; Sim, Jae Hoon; Stenfelt, Stefan; Ihrle, Sebastian; Gerig, Rahel; Pfiffner, Flurin; Eiber, Albrecht; Huber, Alexander M; Röösli, Christof

    2017-11-01

    into a local coordinate system, indicates that the normal component, with spatially varying phase, is dominant above 2 kHz, consistent with local bending vibration modes and traveling surface waves. Both SLDV and 3D LDV data indicate that sound transmission in the skull bone causes rigid-body-like motion at low frequencies whereas transverse deformations and travelling waves were observed above 2 kHz, with propagation speeds of approximately of 450 m/s at 8 kHz. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Sound generated by instability waves of supersonic flows. I Two-dimensional mixing layers. II - Axisymmetric jets

    Science.gov (United States)

    Tam, C. K. W.; Burton, D. E.

    1984-01-01

    An investigation is conducted of the phenomenon of sound generation by spatially growing instability waves in high-speed flows. It is pointed out that this process of noise generation is most effective when the flow is supersonic relative to the ambient speed of sound. The inner and outer asymptotic expansions corresponding to an excited instability wave in a two-dimensional mixing layer and its associated acoustic fields are constructed in terms of the inner and outer spatial variables. In matching the solutions, the intermediate matching principle of Van Dyke and Cole is followed. The validity of the theory is tested by applying it to an axisymmetric supersonic jet and comparing the calculated results with experimental measurements. Very favorable agreements are found both in the calculated instability-wave amplitude distribution (the inner solution) and the near pressure field level contours (the outer solution) in each case.

  11. Finite-difference theory for sound propagation in a lined duct with uniform flow using the wave envelope concept

    Science.gov (United States)

    Baumeister, K. J.

    1977-01-01

    Finite difference equations are derived for sound propagation in a two dimensional, straight, soft wall duct with a uniform flow by using the wave envelope concept. This concept reduces the required number of finite difference grid points by one to two orders of magnitude depending on the length of the duct and the frequency of the sound. The governing acoustic difference equations in complex notation are derived. An exit condition is developed that allows a duct of finite length to simulate the wave propagation in an infinitely long duct. Sample calculations presented for a plane wave incident upon the acoustic liner show the numerical theory to be in good agreement with closed form analytical theory. Complete pressure and velocity printouts are given to some sample problems and can be used to debug and check future computer programs.

  12. Plane Wave-Perturbative Method for Evaluating the Effective Speed of Sound in 1D Phononic Crystals

    Directory of Open Access Journals (Sweden)

    J. Flores Méndez

    2016-01-01

    Full Text Available A method for calculating the effective sound velocities for a 1D phononic crystal is presented; it is valid when the lattice constant is much smaller than the acoustic wave length; therefore, the periodic medium could be regarded as a homogeneous one. The method is based on the expansion of the displacements field into plane waves, satisfying the Bloch theorem. The expansion allows us to obtain a wave equation for the amplitude of the macroscopic displacements field. From the form of this equation we identify the effective parameters, namely, the effective sound velocities for the transverse and longitudinal macroscopic displacements in the homogenized 1D phononic crystal. As a result, the explicit expressions for the effective sound velocities in terms of the parameters of isotropic inclusions in the unit cell are obtained: mass density and elastic moduli. These expressions are used for studying the dependence of the effective, transverse and longitudinal, sound velocities for a binary 1D phononic crystal upon the inclusion filling fraction. A particular case is presented for 1D phononic crystals composed of W-Al and Polyethylene-Si, extending for a case solid-fluid.

  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. [The effect of low-intensity pulsed sound waves delivered by the Exogen device on Staphylococcus aureus morphology and genetics].

    Science.gov (United States)

    Ayan, Irfan; Aslan, Gönül; Cömelekoğlu, Ulkü; Yilmaz, Nejat; Colak, Mehmet

    2008-01-01

    We investigated the effect of low-intensity pulsed sound waves delivered by the Exogen device, which is recommended for the treatment of delayed union and nonunion in orthopedic surgery, on the colony number, antimicrobial susceptibility, bacterial morphology, and genetics of Staphylococcus aureus, which is a frequent pathogen in orthopedic infections. Thirty tubes containing 0.5 McFarland suspensions of S. aureus (ATCC 25923) were used. Fifteen tubes forming the test group were subjected to low-intensity sound waves by the Exogen device for 20 minutes. The remaining 15 tubes were untreated as controls. The two groups were then compared with respect to colony number, antibiotic susceptibility, and genotypic properties. The tubes were examined histologically by electron microscopy. The test tubes treated with sound waves showed a significantly lower number of bacteria colonies compared to the control tubes (psound waves may be beneficial as a prophylactic measure to prevent infections in primary orthopedic operations and as an adjuvant therapy for infected nonunions.

  15. Sound Waves Induce Neural Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells via Ryanodine Receptor-Induced Calcium Release and Pyk2 Activation.

    Science.gov (United States)

    Choi, Yura; Park, Jeong-Eun; Jeong, Jong Seob; Park, Jung-Keug; Kim, Jongpil; Jeon, Songhee

    2016-10-01

    Mesenchymal stem cells (MSCs) have shown considerable promise as an adaptable cell source for use in tissue engineering and other therapeutic applications. The aims of this study were to develop methods to test the hypothesis that human MSCs could be differentiated using sound wave stimulation alone and to find the underlying mechanism. Human bone marrow (hBM)-MSCs were stimulated with sound waves (1 kHz, 81 dB) for 7 days and the expression of neural markers were analyzed. Sound waves induced neural differentiation of hBM-MSC at 1 kHz and 81 dB but not at 1 kHz and 100 dB. To determine the signaling pathways involved in the neural differentiation of hBM-MSCs by sound wave stimulation, we examined the Pyk2 and CREB phosphorylation. Sound wave induced an increase in the phosphorylation of Pyk2 and CREB at 45 min and 90 min, respectively, in hBM-MSCs. To find out the upstream activator of Pyk2, we examined the intracellular calcium source that was released by sound wave stimulation. When we used ryanodine as a ryanodine receptor antagonist, sound wave-induced calcium release was suppressed. Moreover, pre-treatment with a Pyk2 inhibitor, PF431396, prevented the phosphorylation of Pyk2 and suppressed sound wave-induced neural differentiation in hBM-MSCs. These results suggest that specific sound wave stimulation could be used as a neural differentiation inducer of hBM-MSCs.

  16. 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

  17. 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.

  18. Prediction of Sound Waves Propagating Through a Nozzle Without/With a Shock Wave Using the Space-Time CE/SE Method

    Science.gov (United States)

    Wang, Xiao-Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.

    2000-01-01

    The benchmark problems in Category 1 (Internal Propagation) of the third Computational Aeroacoustics (CAA) Work-shop sponsored by NASA Glenn Research Center are solved using the space-time conservation element and solution element (CE/SE) method. The first problem addresses the propagation of sound waves through a nearly choked transonic nozzle. The second one concerns shock-sound interaction in a supersonic nozzle. A quasi one-dimension CE/SE Euler solver for a nonuniform mesh is developed and employed to solve both problems. Numerical solutions are compared with the analytical solution for both problems. It is demonstrated that the CE/SE method is capable of solving aeroacoustic problems with/without shock waves in a simple way. Furthermore, the simple nonreflecting boundary condition used in the CE/SE method which is not based on the characteristic theory works very well.

  19. Heuristic approximations for sound fields produced by spherical waves incident on locally and non-locally reacting planar surfaces.

    Science.gov (United States)

    Li, Kai Ming; Tao, Hongdan

    2014-01-01

    The classic Weyl-van der Pol (WVDP) formula is a well-known asymptotic solution for accurately predicting sound fields above a locally reacting ground surface. However, the form of the WVDP formula is inadequate for predicting sound fields in the vicinity of non-locally reacting surfaces; a correction term is often required in the formula to provide accurate numerical solutions. Even with this correction, there is a singularity in the diffraction wave term when the source is located directly above or below the receiver. This paper explores a heuristic method to remove this singularity and suggests an analytical form comparable to the WVDP formula. This improved formula offers a physically interpretable solution and allows for accurate predictions of the total sound field above locally and non-locally reacting surfaces for all geometrical configurations.

  20. SPH Simulation of Acoustic Waves: Effects of Frequency, Sound Pressure, and Particle Spacing

    Directory of Open Access Journals (Sweden)

    Y. O. Zhang

    2015-01-01

    Full Text Available Acoustic problems consisting of multiphase systems or with deformable boundaries are difficult to describe using mesh-based methods, while the meshfree, Lagrangian smoothed particle hydrodynamics (SPH method can handle such complicated problems. In this paper, after solving linearized acoustic equations with the standard SPH theory, the feasibility of the SPH method in simulating sound propagation in the time domain is validated. The effects of sound frequency, maximum sound pressure amplitude, and particle spacing on numerical error and time cost are then subsequently discussed based on the sound propagation simulation. The discussion based on a limited range of frequency and sound pressure demonstrates that the rising of sound frequency increases simulation error, and the increase is nonlinear, whereas the rising sound pressure has limited effects on the error. In addition, decreasing the particle spacing reduces the numerical error, while simultaneously increasing the CPU time. The trend of both changes is close to linear on a logarithmic scale.

  1. 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

  2. Effect of a progressive sound wave on the profiles of spectral lines. 2: Asymmetry of faint Fraunhofer lines. [absorption spectra

    Science.gov (United States)

    Kostyk, R. I.

    1974-01-01

    The absorption coefficient profile was calculated for lines of different chemical elements in a medium with progressive sound waves. Calculations show that (1) the degree and direction of asymmetry depend on the atomic ionization potential and the potential of lower level excitation of the individual line; (2) the degree of asymmetry of a line decreases from the center toward the limb of the solar disc; and (3) turbulent motions 'suppress' the asymmetry.

  3. Interference pattern of the sound field in the presence of an internal Kelvin wave in a stratified lake.

    Science.gov (United States)

    Katsnelson, Boris; Lunkov, Andrey; Ostrovsky, Ilia

    2016-02-01

    Internal Kelvin waves (IKWs) initiated by rotation of the Earth are one of the main hydrodynamic phenomena in large stratified lakes where baroclinic Rossby radius of deformation is smaller than the horizontal scale of the lake. IKWs can be identified using the spectra of internal waves, where in the presence of IKWs, the inertial frequency is at maximum. IKWs play a rather important role in the lake's dynamics for different processes, both in the water layer and sediment, especially at the periphery of lake. Due to influence of internal waves on the sound propagation, acoustical methods can be used for estimation of behaviour of IKWs. In this paper, the spatiotemporal variability of the mid-frequency (∼1 kHz) sound field in the presence of IKWs in a deep stratified Lake Kinneret is studied using numerical simulations based on normal-mode theory. Due to the specific character of perturbation of the water layer, IKWs can cause specific variations of interference pattern, in particular, a significant shift of the sound interference pattern both in spatial and frequency domain. These shifts can be easily measured and used for reconstruction of IKW parameters.

  4. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    Science.gov (United States)

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeão; Sousa, Adriano Sampaioe

    2011-09-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels.1-4 Experimental studies usually involve expensive and sophisticated equipment that is out of reach of school laboratory facilities.3-6 In this paper we show how to investigate quantitatively the sounds produced by a flexible sound tube corrugated on the inside by using educational equipment readily available in school laboratories, such as the oscilloscope, the microphone, the anemometer, and the air pump. We show that it is possible for students to study the discontinuous spectrum of sounds produced by a flexible corrugated tube and go even further, computing the speed of sound in air with a simple experimental procedure.

  5. Properties of the Circumsolar Plasma Turbulence and Plasma Waves According to the Coronal Sounding Experiments Using Spacecraft Signals

    Science.gov (United States)

    Yakovlev, O. I.

    2017-10-01

    We report on the results of studying the circumsolar plasma turbulence according to the coronal sounding experiments using spacecraft signals. Statistical characteristics of the temporal fluctuation spectra of the amplitude, phase, frequency, and Faraday rotation angle of the radio-wave polarization plane are described for the solar offset distances of the ray path in the range between 3 and 40 solar radii. Information on the turbulence spectra is given and the spectral index, as well as the outer and inner turbulence scales, as functions of the heliocentric distance are presented. The effect on the measured parameters of the plasma waves is discussed and typical values of the wave periods for different distances from the Sun are given.

  6. Channel Sounding System for MM-Wave Bands and Characterization of Indoor Propagation at 28 GHz

    DEFF Research Database (Denmark)

    Hejselbæk, Johannes; Ji, Yilin; Fan, Wei

    2017-01-01

    The aim of this work is to present a vector network analyzer (VNA) based channel sounding sys- tem capable of performing measurements in the range from 2 to 50 GHz. Further, this paper describes an indoor measurement campaign performed at 26 to 30 GHz. The sounding system is capable of receiving...

  7. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    Science.gov (United States)

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeao; Sousa, Adriano Sampaioe

    2011-01-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels. Experimental studies usually…

  8. Combined effect of pulsed electromagnetic field and sound wave on In vitro and In vivo neural differentiation of human mesenchymal stem cells.

    Science.gov (United States)

    Choi, Yun-Kyong; Urnukhsaikhan, Enerelt; Yoon, Hee-Hoon; Seo, Young-Kwon; Cho, Hyunjin; Jeong, Jong-Seob; Kim, Soo-Chan; Park, Jung-Keug

    2017-01-01

    Biophysical wave stimulus has been used as an effective tool to promote cellular maturation and differentiation in the construction of engineered tissue. Pulsed electromagnetic fields (PEMFs) and sound waves have been selected as effective stimuli that can promote neural differentiation. The aim of this study was to investigate the synergistic effect of PEMFs and sound waves on the neural differentiation potential in vitro and in vivo using human bone marrow mesenchymal stem cells (hBM-MSCs). In vitro, neural-related genes in hBM-MSCs were accelerated by the combined exposure to both waves more than by individual exposure to PEMFs or sound waves. The combined wave also up-regulated the expression of neural and synaptic-related proteins in a three-dimensional (3-D) culture system through the phosphorylation of extracellular signal-related kinase. In a mouse model of photochemically induced ischemia, exposure to the combined wave reduced the infarction volume and improved post-injury behavioral activity. These results indicate that a combined stimulus of biophysical waves, PEMFs and sound can enhance and possibly affect the differentiation of MSCs into neural cells. Our study is meaningful for highlighting the potential of combined wave for neurogenic effects and providing new therapeutic approaches for neural cell therapy. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:201-211, 2017. © 2016 American Institute of Chemical Engineers.

  9. 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.

  10. Making waves: the use of sound by a mosquito and three moth species

    OpenAIRE

    Hart, Melanie

    2012-01-01

    Mosquitoes hear wingbeat sounds with antennal Johnston’s organs. In males, their sensitivity is thought to be enhanced by long fibrils on the antennae; males of many species erect these fibrils before they swarm with females. I investigated the anatomy and acoustic properties of antennae of male and female Aedes togoi, a species whose males erect these long fibrils before swarming. Many moths also hear, but several species that communicate with wingbeat sound have no tympanal organs, sensitiv...

  11. Energy density of standing sound waves at the radiation-dominated phase of the universe expansion (hydrodynamic derivation)

    Science.gov (United States)

    Inogamov, N. A.; Sunyaev, R. A.

    2015-12-01

    In the early Universe up to hydrogen recombination in the Universe, the radiation pressure was much greater than the pressure of baryons and electrons. Moreover, the energy density of cosmic microwave background (CMB) photons was greater than or close to the energy density contained in the rest mass of baryonic matter, i.e., the primordial plasma was a radiated-dominated one and the adiabatic index was close to 4/3. The small density perturbations from which the observed galaxies have grown grew as long as the characteristic perturbation scales exceeded the horizon of the Universe сt at that time. On smaller scales, the density perturbations were standing sound waves. Radiative viscosity and heat conduction must have led to the damping of sound waves on very small scales. After the discovery of the cosmic microwave background, J. Silk calculated the scales of this damping, which is now called Silk damping, knowing the CMBtemperature and assuming the density of baryons and electrons. Observations with the South Pole Telescope, the Atacama Cosmology Telescope, and the Planck satellite have revealed the predicted damping of acoustic peaks in the CMB power spectrum and confirmed one important prediction of the theory. In 1970, R.A. Sunyaev and Ya.B. Zeldovich showed that such energy release in the early Universe should lead to characteristic deviations of the CMB spectrum from the Planck one. The development of the technology of cryogenic detectors of submillimeter and millimeter wavelength radiation has made it possible to measure the CMB spectral distortions at 10-8 of its total intensity (PIXIE). This has sharply increased the interest of theoretical cosmologists in the problem of energy release when smallscale sound waves are damped. We have derived a relativistic formula for the energy of a standing sound wave in a photon-baryon-electron plasma from simple hydrodynamic and thermodynamic relations. This formula is applicable for an arbitrary relation between the

  12. The influence of inhomogeneous temperature distribution on the amplification of sound waves in non-equilibrium gas media

    Science.gov (United States)

    Suleimenov, I.; Aushev, V.; Adamov, T.; Vasiliev, I.

    Modern investigations show that the effect of acoustic and acoustic-gravity waves amplification strongly influence on the temperature balance in atmosphere. These waves may be amplified due to the transformation of energy of chemically active (or ionized) components into the energy of wave motion, i.e. the nature of the effect is the same as the amplification of sound in other non-equilibrium gas media (for example, in gas discharge plasma). Recently Jiyao Xu (1999) reported that the theory of such waves might be developed in the same way as the theory of acoustic-gravity waves. It is shown that the influence of inhomogeneous altitude distribution of temperature should be taken into account for the correct interpretation of temperature balance in the atmosphere. In other words, the self-agreed problem have to be solved: transformation of chemical energy into energy of wave motion change the vertical profile of the atmosphere temperature, but the profile of the temperature itself determine the amplification coefficient of the wave. The results of analytical solution of the problem are reported. We show that the sign of temperature gradient strongly influence on the behavior of amplified acoustic and acoustic-gravity waves. The regime of amplification is stable when the second derivative of the temperature is negative (temperature has minimum at some point). In other words the stable channel of amplification of the waves may exist, for example, in the tube when the temperature of the walls is higher than the temperature of the gas at the axe. The different instabilities appear in the opposite case when the temperature in the reference point has a maximum. In particular, it means that the amplification of acoustic waves in gas discharge tubes cannot be stable. Moreover, our results show that self-generation of acoustic-gravity in middle atmosphere due to photochemical reactions cannot be stable process too. This conclusion is in accordance with known experimental

  13. Bottom attenuation estimation using sound intensity fluctuations due to mode coupling by nonlinear internal waves in shallow water.

    Science.gov (United States)

    Grigorev, Valery A; Katsnelson, Boris G; Lynch, James F

    2016-11-01

    Analyses of fluctuations of low frequency signals (300 ± 30 Hz) propagating in shallow water in the presence of nonlinear internal waves (NIWs) in the Shallow Water 2006 experiment are carried out. Signals were received by a vertical line array at a distance of ∼20 km from the source. A NIW train was moving totally inside of the acoustic track, and the angle between the wave front of the NIW and the acoustic track in the horizontal plane was ∼10°. It is shown that the spectrum of the sound intensity fluctuations contains peaks corresponding to the coupling of pairs of propagating modes. Analysis of spectra at different hydrophone depths, and also summed over depth allows the authors to estimate attenuation in the bottom sediments.

  14. Evidence for two-dimensional solitary sound waves in a lipid controlled interface and its implications for biological signalling.

    Science.gov (United States)

    Shrivastava, Shamit; Schneider, Matthias F

    2014-08-06

    Biological membranes by virtue of their elastic properties should be capable of propagating localized perturbations analogous to sound waves. However, the existence and the possible role of such waves in communication in biology remain unexplored. Here, we report the first observations of two-dimensional solitary elastic pulses in lipid interfaces, excited mechanically and detected by FRET. We demonstrate that the nonlinearity near a maximum in the susceptibility of the lipid monolayer results in solitary pulses that also have a threshold for excitation. These experiments clearly demonstrate that the state of the interface regulates the propagation of pulses both qualitatively and quantitatively. Finally, we elaborate on the striking similarity of the observed phenomenon to nerve pulse propagation and a thermodynamic basis of cell signalling in general. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  15. 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.

  16. 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.

  17. Space-Borne Radio-Sounding Investigations Facilitated by the Virtual Wave Observatory (VWO)

    Science.gov (United States)

    Benson, Robert F.; Fung, Shing F.; Bilitza,Dieter; Garcia, Leonard N.; Shao, Xi; Galkin, Ivan A.

    2011-01-01

    The goal of the Virtual Wave Observatory (VWO) is to provide userfriendly access to heliophysics wave data. While the VWO initially emphasized the vast quantity of wave data obtained from passive receivers, the VWO infrastructure can also be used to access active sounder data sets. Here we use examples from some half-million Alouette-2, ISIS-1, and ISIS-2 digital topside-sounder ionograms to demonstrate the desirability of such access to the actual ionograms for investigations of both natural and sounder-stimulated plasma-wave phenomena. By this demonstration, we wish to encourage investigators to make other valuable space-borne sounder data sets accessible via the VWO.

  18. Mid-frequency sound propagation through internal waves at short range with synoptic oceanographic observations.

    Science.gov (United States)

    Rouseff, Daniel; Tang, Dajun; Williams, Kevin L; Wang, Zhongkang; Moum, James N

    2008-09-01

    Preliminary results are presented from an analysis of mid-frequency acoustic transmission data collected at range 550 m during the Shallow Water 2006 Experiment. The acoustic data were collected on a vertical array immediately before, during, and after the passage of a nonlinear internal wave on 18 August, 2006. Using oceanographic data collected at a nearby location, a plane-wave model for the nonlinear internal wave's position as a function of time is developed. Experimental results show a new acoustic path is generated as the internal wave passes above the acoustic source.

  19. 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

  20. Page 1 290 R. Bär sound waves are only excited during the time of ...

    Indian Academy of Sciences (India)

    disappear by shielding off the portion of the liquid close to the sound-quartz. An analogous wing can also be generated by placing a brass-rod, which must only be a few degrees warmer than the liquid, for some seconds in contact with the glass wall of the vessel, on which the quartz is cemented. Conversely a wing on the ...

  1. A sound idea: Manipulating domain walls in magnetic nanowires using surface acoustic waves

    Science.gov (United States)

    Dean, J.; Bryan, M. T.; Cooper, J. D.; Virbule, A.; Cunningham, J. E.; Hayward, T. J.

    2015-10-01

    We propose a method of pinning and propagating domain walls in artificial multiferroic nanowires using electrically induced surface acoustic waves. Using finite-element micromagnetic simulations and 1D semi-analytical modelling, we demonstrate how a pair of interdigitated acoustic transducers can remotely induce an array of attractive domain wall pinning sites by forming a standing stress/strain wave along a nanowire's length. Shifts in the frequencies of the surface acoustic waves allow multiple domain walls to be synchronously transported at speeds up to 50 ms-1. Our study lays the foundation for energy-efficient domain wall devices that exploit the low propagation losses of surface acoustic waves to precisely manipulate large numbers of data bits.

  2. Superresolution through the topological shaping of sound with an acoustic vortex wave antenna

    CERN Document Server

    Guild, Matthew D; Martin, Theodore P; Rohde, Charles A; Orris, Gregory J

    2016-01-01

    In this paper, we demonstrate far-field acoustic superresolution using shaped acoustic vortices. Compared with previously proposed near-field methods of acoustic superresolution, in this work we describe how far-field superresolution can be obtained using an acoustic vortex wave antenna. This is accomplished by leveraging the recent advances in optical vortices in conjunction with the topological diversity of a leaky wave antenna design. In particular, the use of an acoustic vortex wave antenna eliminates the need for a complicated phased array consisting of multiple active elements, and enables a superresolving aperture to be achieved with a single simple acoustic source and total aperture size less than a wavelength in diameter. A theoretical formulation is presented for the design of an acoustic vortex wave antenna with arbitrary planar arrangement, and explicit expressions are developed for the radiated acoustic pressure field. This geometric versatility enables variously-shaped acoustic vortex patterns t...

  3. Dynamic acoustics for the STAR-100. [computer algorithms for time dependent sound waves in jet

    Science.gov (United States)

    Bayliss, A.; Turkel, E.

    1979-01-01

    An algorithm is described to compute time dependent acoustic waves in a jet. The method differs from previous methods in that no harmonic time dependence is assumed, thus permitting the study of nonharmonic acoustical behavior. Large grids are required to resolve the acoustic waves. Since the problem is nonstiff, explicit high order schemes can be used. These have been adapted to the STAR-100 with great efficiencies and permitted the efficient solution of problems which would not be feasible on a scalar machine.

  4. Calculating Speed of Sound

    Science.gov (United States)

    Bhatnagar, Shalabh

    2017-01-01

    Sound is an emerging source of renewable energy but it has some limitations. The main limitation is, the amount of energy that can be extracted from sound is very less and that is because of the velocity of the sound. The velocity of sound changes as per medium. If we could increase the velocity of the sound in a medium we would be probably able to extract more amount of energy from sound and will be able to transfer it at a higher rate. To increase the velocity of sound we should know the speed of sound. If we go by the theory of classic mechanics speed is the distance travelled by a particle divided by time whereas velocity is the displacement of particle divided by time. The speed of sound in dry air at 20 °C (68 °F) is considered to be 343.2 meters per second and it won't be wrong in saying that 342.2 meters is the velocity of sound not the speed as it's the displacement of the sound not the total distance sound wave covered. Sound travels in the form of mechanical wave, so while calculating the speed of sound the whole path of wave should be considered not just the distance traveled by sound. In this paper I would like to focus on calculating the actual speed of sound wave which can help us to extract more energy and make sound travel with faster velocity.

  5. Temperature dependence of sound wave propagation in as a diagnostic tools for healthy and rotten black alder (Alnus glutinosa (L.) Gaertn.) tree trunks

    OpenAIRE

    Orzechowski, Michał; Budniak, Piotr

    2013-01-01

    The aim of this study was to determine how thermal conditions affect the speed of sound wave propagation, in trunks of living alder Alnus glutinosa (L.) Gaertn. trees. This method in practiced when diagnosing the presence of intern.al decay in standing trees. Field work was carried out four times at different temperatures (+13°C, +3°C, -7°C and -16°C) using an lmpulse Hammer. There was a significant correlation between the thermal conditions and the speed of sound wave propaga...

  6. Noncontact, nondestructive elasticity evaluation of sound and demineralized human dental enamel using a laser ultrasonic surface wave dispersion technique

    Science.gov (United States)

    Wang, Hsiao-Chuan; Fleming, Simon; Lee, Yung-Chun; Law, Susan; Swain, Michael; Xue, Jing

    2009-09-01

    Laser ultrasonic nondestructive evaluation (NDE) methods have been proposed to replace conventional in vivo dental clinical diagnosis tools that are either destructive or incapable of quantifying the elasticity of human dental enamel. In this work, a laser NDE system that can perform remote measurements on samples of small dimensions is presented. A focused laser line source is used to generate broadband surface acoustic wave impulses that are detected with a simplified optical fiber interferometer. The measured surface wave velocity dispersion spectrum is in turn used to characterize the elasticity of the specimen. The NDE system and the analysis technique are validated with measurements of different metal structures and then applied to evaluate human dental enamel. Artificial lesions are prepared on the samples to simulate different states of enamel elasticity. Measurement results for both sound and lesioned regions, as well as lesions of different severity, are clearly distinguishable from each other and fit well with physical expectations and theoretical value. This is the first time, to the best of our knowledge, that a laser-based surface wave velocity dispersion technique is successfully applied on human dental enamel, demonstrating the potential for noncontact, nondestructive in vivo detection of the development of carious lesions.

  7. 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.

  8. 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.

  9. 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…

  10. Propagation of sound waves through a linear shear layer: A closed form solution

    Science.gov (United States)

    Scott, J. N.

    1978-01-01

    Closed form solutions are presented for sound propagation from a line source in or near a shear layer. The analysis was exact for all frequencies and was developed assuming a linear velocity profile in the shear layer. This assumption allowed the solution to be expressed in terms of parabolic cyclinder functions. The solution is presented for a line monopole source first embedded in the uniform flow and then in the shear layer. Solutions are also discussed for certain types of dipole and quadrupole sources. Asymptotic expansions of the exact solutions for small and large values of Strouhal number gave expressions which correspond to solutions previously obtained for these limiting cases.

  11. Propagation of sound waves through a linear shear layer - A closed form solution

    Science.gov (United States)

    Scott, J. N.

    1978-01-01

    Closed form solutions are presented for sound propagation from a line source in or near a shear layer. The analysis is exact for all frequencies and is developed assuming a linear velocity profile in the shear layer. This assumption allows the solution to be expressed in terms of parabolic cylinder functions. The solution is presented for a line monopole source first embedded in the uniform flow and then in the shear layer. Solutions are also discussed for certain types of dipole and quadrupole sources. Asymptotic expansions of the exact solutions for small and large values of Strouhal number give expressions which correspond to solutions previously obtained for these limiting cases.

  12. Sound waves and flexural mode dynamics in two-dimensional crystals

    Science.gov (United States)

    Michel, K. H.; Scuracchio, P.; Peeters, F. M.

    2017-09-01

    Starting from a Hamiltonian with anharmonic coupling between in-plane acoustic displacements and out-of-plane (flexural) modes, we derived coupled equations of motion for in-plane displacements correlations and flexural mode density fluctuations. Linear response theory and time-dependent thermal Green's functions techniques are applied in order to obtain different response functions. As external perturbations we allow for stresses and thermal heat sources. The displacement correlations are described by a Dyson equation where the flexural density distribution enters as an additional perturbation. The flexural density distribution satisfies a kinetic equation where the in-plane lattice displacements act as a perturbation. In the hydrodynamic limit this system of coupled equations is at the basis of a unified description of elastic and thermal phenomena, such as isothermal versus adiabatic sound motion and thermal conductivity versus second sound. The general theory is formulated in view of application to graphene, two-dimensional h-BN, and 2H-transition metal dichalcogenides and oxides.

  13. Families of exact solutions for linear and nonlinear wave equations with a variable speed of sound and their use in solving initial boundary value problems

    Science.gov (United States)

    Trifonov, E. V.

    2017-07-01

    We propose a procedure for multiplying solutions of linear and nonlinear one-dimensional wave equations, where the speed of sound can be an arbitrary function of one variable. We obtain exact solutions. We show that the functional series comprising these solutions can be used to solve initial boundary value problems. For this, we introduce a special scalar product.

  14. Ultrawideband VNA Based Channel Sounding System for Centimetre and Millimetre Wave Bands

    DEFF Research Database (Denmark)

    Hejselbæk, Johannes; Fan, Wei; Pedersen, Gert F.

    2016-01-01

    Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations of an exi......Channel characterization of multipath channels at centimetre and millimetre wave bands is of interest from both academia and industry, especially for the frequency bands that are under consideration for 5G mobile communication systems. In this paper, we first demonstrate the limitations...... utilizing the proposed setup equipped with rotational directive horn antennas, with a focus on multi-band power-angle-delay profiles, was performed. The measured frequency bands are 18 - 20 GHz, 25 - 27 GHz, 28 - 30 GHz and 38 - 40 GHz....

  15. Effects of Internal Waves on Sound Propagation in the Shallow Waters of the Continental Shelves

    Science.gov (United States)

    2016-09-01

    changes are small in the experiment area as there was no introduction of fresh water into the region. An average salinity of 34.44 psu was used for the...14  E.  INTERNAL WAVE FRONTS IN THE EXPERIMENT AREA ........15  F.  TRANSLATING WATER ...For this study, a constant salinity throughout the water column was assumed, as there was no introduction of fresh water into the region. Hence

  16. The radiation of sound by the instability waves of a compressible plane turbulent shear layer

    Science.gov (United States)

    Tam, C. K. W.; Morris, P. J.

    1980-01-01

    The problem of acoustic radiation generated by instability waves of a compressible plane turbulent shear layer is solved. The solution provided is valid up to the acoustic far-field region. It represents a significant improvement over the solution obtained by classical hydrodynamic-stability theory which is essentially a local solution with the acoustic radiation suppressed. The basic instability-wave solution which is valid in the shear layer and the near-field region is constructed in terms of an asymptotic expansion using the method of multiple scales. This solution accounts for the effects of the slightly divergent mean flow. It is shown that the multiple-scales asymptotic expansion is not uniformly valid far from the shear layer. Continuation of this solution into the entire upper half-plane is described. The extended solution enables the near- and far-field pressure fluctuations associated with the instability wave to be determined. Numerical results show that the directivity pattern of acoustic radiation into the stationary medium peaks at 20 degrees to the axis of the shear layer in the downstream direction for supersonic flows. This agrees qualitatively with the observed noise-directivity patterns of supersonic jets.

  17. Room acoustics analysis using circular arrays: an experimental study based on sound field plane-wave decomposition.

    Science.gov (United States)

    Torres, Ana M; Lopez, Jose J; Pueo, Basilio; Cobos, Maximo

    2013-04-01

    Plane-wave decomposition (PWD) methods using microphone arrays have been shown to be a very useful tool within the applied acoustics community for their multiple applications in room acoustics analysis and synthesis. While many theoretical aspects of PWD have been previously addressed in the literature, the practical advantages of the PWD method to assess the acoustic behavior of real rooms have been barely explored so far. In this paper, the PWD method is employed to analyze the sound field inside a selected set of real rooms having a well-defined purpose. To this end, a circular microphone array is used to capture and process a number of impulse responses at different spatial positions, providing angle-dependent data for both direct and reflected wavefronts. The detection of reflected plane waves is performed by means of image processing techniques applied over the raw array response data and over the PWD data, showing the usefulness of image-processing-based methods for room acoustics analysis.

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

    Science.gov (United States)

    Eltayeb, I. A.; Elbashir, T. B. A.

    2017-08-01

    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.

  19. 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.

  20. High-speed helicopter rotor noise - Shock waves as a potent source of sound

    Science.gov (United States)

    Farassat, F.; Lee, Yung-Jang; Tadghighi, H.; Holz, R.

    1991-01-01

    In this paper we discuss the problem of high speed rotor noise prediction. In particular, we propose that from the point of view of the acoustic analogy, shocks around rotating blades are sources of sound. We show that, although for a wing at uniform steady rectilinear motion with shocks the volume quadrupole and shock sources cancel in the far field to the order of 1/r, this cannot happen for rotating blades. In this case, some cancellation between volume quadrupoles and shock sources occurs, yet the remaining shock noise contribution is still potent. A formula for shock noise prediction is presented based on mapping the deformable shock surface to a time independent region. The resulting equation is similar to Formulation 1A of Langley. Shock noise prediction for a hovering model rotor for which experimental noise data exist is presented. The comparison of measured and predicted acoustic data shows good agreement.

  1. Possibility to sound the atmospheric ozone by a radiosonde equipped with two temperature sensors, sensitive and non-sensitive to the long wave radiation

    Science.gov (United States)

    Kitaoka, T.; Sumi, T.

    1994-01-01

    The sensitiveness of white coated thermistor sensors and non-sensitiveness of the gold coated over white thermistor sensors (which have been manufactured by a vacuum evaporation process) to long wave radiation were ascertained by some simple experiments in-room and also by analyses of some results of experimental soundings. From results of analyses on the temperature discrepancies caused by long wave radiation, the possibility to sound the atmospheric ozone partial pressure by a radiosonde equipped with two kinds of sensors, sensitive and non-sensitive to the long wave radiation was suggested, and the test results of the newly developed software for the deduction of ozone partial pressure in upper layers was also shown. However, it was found that the following is the necessary condition to realize the purpose. The sounding should be made by a radiosonde equipped with three sensors, instead of two, one being non-sensitive to the long wave radiation perfectly, and the other two also non-sensitive partially to the downward one, with two different angles of exposure upward. It is essential for the realization of the purpose to get two different values of temperature discrepancies simultaneously observed by the three sensors mentioned above and to avoid the troublesome effects of the upward long wave radiation.

  2. Intensity fluctuations of midfrequency sound signals passing through moving nonlinear internal waves.

    Science.gov (United States)

    Katsnelson, Boris; Grigorev, Valery; Lynch, James F

    2008-09-01

    The fluctuations of intensity of broadband pulses in the midfrequency range (2-4.5 kHz) propagating in shallow water in the presence of intense internal waves moving approximately along the acoustic track are considered. These pulses were received by two separate single hydrophones placed at different distances from the source (approximately 4 and approximately 12 km) and in different directions. It is shown that the frequency spectra of the fluctuations for these hydrophones have different predominating frequencies corresponding with the directions of the acoustic track. Comparisons of experimental results with theoretical estimates demonstrate good consistency.

  3. A Variational Formulation for the Finite Element Analysis of Sound Wave Propagation in a Spherical Shell

    Science.gov (United States)

    Lebiedzik, Catherine

    1995-01-01

    Development of design tools to furnish optimal acoustic environments for lightweight aircraft demands the ability to simulate the acoustic system on a workstation. In order to form an effective mathematical model of the phenomena at hand, we have begun by studying the propagation of acoustic waves inside closed spherical shells. Using a fully-coupled fluid-structure interaction model based upon variational principles, we have written a finite element analysis program and are in the process of examining several test cases. Future investigations are planned to increase model accuracy by incorporating non-linear and viscous effects.

  4. Ionospheric disturbances caused by long period sound waves generated by Saturn-Apollo launches

    Science.gov (United States)

    Rao, G. L.

    1972-01-01

    Wavelike disturbances were observed in the ionosphere following several nuclear explosions in early 1960's. Supersonic shock waves within the atmosphere generated by large rockets can cause ionospheric electron density perturbations. A CW phase path Doppler array in the New York area was operated during the Saturn-Apollo 12 and 13 launches and recorded Doppler frequency fluctuations due to rocket launchings. Cross correlation and power spectral analyses of the phase path-path Doppler frequency variation records showed that the phase velocities of the signal arrivals were from south of the array with 700 - 800 m/sec corresponding to periods in the range of 2 to 4 minutes. Ionograms taken every 60 seconds from Wallops Islands showed clearly ionospheric disturbances due to rockets. The group velocities were estimated to be of the order of 450 m/sec 1 obtained from the earliest visible disturbances seen on CW phase path Doppler records and ionograms together with the rocket trajectory data.

  5. Creep of sound paths in consolidated granular material detected through coda wave interferometry

    Science.gov (United States)

    Espíndola, David; Galaz, Belfor; Melo, Francisco

    2016-07-01

    The time evolution of the contact force structure of a consolidated granular material subjected to a constant stress is monitored using the coda wave interferometry method. In addition, the nature of the aging and rejuvenation processes are investigated. These processes are interpreted in terms of affine and nonaffine structural path deformations. During the later stages of creep, the rearrangements of subgrains are so small that they only produce affine deformations in the contact paths, without any significant changes in the structural configuration. As a result, the strain path distribution follows the macroscopic strain. Conversely, in the presence of ultrasonic perturbations, the nonaffine grain buckling mechanism dominates, producing relatively drastic changes in the structural configuration accompanied by path deformations of the order of the grain size. This plastic mechanism induces material rejuvenation that is observed macroscopically as an ultrasonically accelerated creep.

  6. 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: http://www.ias.ac.in/article/fulltext/reso/004/06/0015-0019 ...

  7. Second Sound

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 3. Second Sound - Waves of Entropy and Temperature. R Srinivasan. General Article Volume 4 Issue 3 March 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/03/0016-0024 ...

  8. Scattering Cross Section of Sound Waves by the Modal Element Method

    Science.gov (United States)

    Baumeister, Kenneth J.; Kreider, Kevin L.

    1994-01-01

    #he modal element method has been employed to determine the scattered field from a plane acoustic wave impinging on a two dimensional body. In the modal element method, the scattering body is represented by finite elements, which are coupled to an eigenfunction expansion representing the acoustic pressure in the infinite computational domain surrounding the body. The present paper extends the previous work by developing the algorithm necessary to calculate the acoustics scattering cross section by the modal element method. The scattering cross section is the acoustical equivalent to the Radar Cross Section (RCS) in electromagnetic theory. Since the scattering cross section is evaluated at infinite distance from the body, an asymptotic approximation is used in conjunction with the standard modal element method. For validation, the scattering cross section of the rigid circular cylinder is computed for the frequency range 0.1 is less than or equal to ka is less than or equal to 100. Results show excellent agreement with the analytic solution.

  9. Variation of gravity waves on different time scales and the differences between day and nighttime lidar soundings at mid-latitudes

    Science.gov (United States)

    Baumgarten, Kathrin; Gerding, Michael; Luebken, Franz-Josef

    2017-04-01

    A daylight capable Rayleigh-Mie-Raman (RMR) lidar is in operation since summer 2010 at the mid-latitude station at Kühlungsborn (54° N, 12° E). The RMR lidar system is used for measuring wave structures at day and night to investigate short and long periodic atmospheric waves, like gravity waves (GW) and thermal tides (with diurnal, semidiurnal and terdiurnal components) between 30 and 70 km altitude. An extensive data set with over 7500 measurements hours allows deriving the seasonal variation of, e.g., gravity wave potential energy density (GWPED), while several multi-day observations show the variability of gravity waves and tides on shorter time scales. To separate gravity waves, tides and other long periodic waves a 1-dimensional spectral filtering technique is used. The seasonal variation of the potential energy per unit volume shows a clear summer minimum for inertia gravity waves as well as for tides. Contrary to this, short periodic gravity waves with periods between 4 and 8 h show no clear seasonal variation. Especially for altitudes above 55 km an additional semiannual component with a second summer maximum is observed, which shows the increasing relevance of these waves. Because of the availability of whole day data, we have the possibility to distinguish between day and nighttime data. By using only data between 20 UT and 4 UT ("nighttime") we found a summer minimum in GWPED that is hidden in the whole day data. We relate these differences in the seasonal behavior to a diurnal variation of propagation conditions for the particular gravity waves. Beside the monthly averaged data, we will present a 10-day continuous lidar sounding to show the variability of gravity waves and tides on short time scales.

  10. Underwater Sound Filtering

    NARCIS (Netherlands)

    Rutger van Aalst; Ines Simic

    2015-01-01

    This paper describes a possible solution to the underwater sound filtering problem, using Blind Source Separation. The problem regards splitting sound from a boat engine and the water waves to prove the possibility to extract one sound fragment from the other on the open sea. The illustrations shown

  11. The propagation of detonation waves in non-ideal condensed-phase explosives confined by high sound-speed materials

    Science.gov (United States)

    Schoch, Stefan; Nikiforakis, Nikolaos; Lee, Bok Jik

    2013-08-01

    Highly non-ideal condensed-phase explosives used by the mining industry have a strong detonation velocity dependence on the charge dimension. Detonation velocities can be as low as one third of the theoretically calculated ideal detonation velocity in charge radii close to the failure radius. Under these detonation conditions the flow in the confiner can become subsonic, a flow condition under which classical shock-polar analysis is not applicable. This restriction prohibits the use of popular engineering models like detonation shock dynamics and Wood-Kirkwood type models under these confinement conditions. In addition, it has been found in the literature that subsonic flow in the confiner will increase the influence of the confining material on the detonation performance. In this work, we use a multi-phase model coupled to an elastic-plastic model (for the representation of a confiner) to explore the interaction of detonations under these confiner conditions. An ammonium nitrate based mining emulsion is investigated in aluminium and steel confinement of finite and infinite thickness representing the confiner as either a fluid or an elastic-plastic material. It is found that the presence of elastic waves is negligible close to ideal detonation conditions, but is important close to the failure radius and in detonation conditions with subsonic flow in the confiner. High sound-speed confiners support the detonation through energy transport ahead of the detonation front if desensitisation effects are negligible. The detonation front profiles are found to remain convex even in the most non-ideal detonation conditions, and the detonation front curvature only becomes concave in a localised region close to the confiner edge.

  12. The Textile Form of Sound

    DEFF Research Database (Denmark)

    Bendixen, Cecilie

    of sound. This issue is a part of a Ph.D. study at The Danish Design School in Copenhagen. Sound diffusion in architecture is a complex phenomenon. From the sound source the sound spreads in all directions as a sphere of wave fronts. When the sound is reflected from room boundaries or furniture, complex...... 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.......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...

  13. 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.

  14. Objective sound wave amplitude measurement generated by a tuning fork. An analysis of its use as a diagnostic tool in suspected femoral neck fractures.

    Science.gov (United States)

    Jawad, Z; Odumala, A; Jones, M

    2012-06-01

    Hip injuries are becoming a more common problem as the elderly population increases and their management represents a significant proportion of health care costs. Diagnosis of a fracture based on clinical assessment and plain films is not always conclusive and further investigations for such occult fractures, such as magnetic resonance imaging (MRI), are sometimes required which are expensive and may be difficult to access. Disruption to the conduction of a sound wave travelling through a fractured bone is a concept that has been used to diagnose fractures. In our study we used a tuning fork with frequency of 128 Hz to objectively measure the reduction in sound amplitude in fractured and non-fractured hips. We looked at the feasibility of using this test as a diagnostic tool for neck of femur fractures. A total of 20 patients was included in the study, using MRI scan as the standard for comparison of diagnostic findings. Informed consent was obtained from the patients. There was a significant difference in the amplitude reduction of the sound waves when comparing normal to fractured hips. This was 0.9 in normal hips, compared to 0.31 and 0.18 in intra-capsular and extra-capsular fractures, respectively. Our test was 80% accurate at diagnosing neck of femur fractures. In conclusion this test may be used as a diagnostic test or screening tool in the assessment of occult hip fractures. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Searching Sound with Sound

    OpenAIRE

    Parker, Martin; Chapman, A.

    2010-01-01

    A sound installation developed to accompany Anna Chapman's sound installtion "Subjects for Melancholy Retrospection" that was presented t the Edinburgh Art Festrival in August 2010 at the National Trust for Scotland's Newhailes estate.

  16. Acoustic spin pumping: Direct generation of spin currents from sound waves in Pt/Y3Fe5O12 hybrid structures

    Science.gov (United States)

    Uchida, K.; Adachi, H.; An, T.; Nakayama, H.; Toda, M.; Hillebrands, B.; Maekawa, S.; Saitoh, E.

    2012-03-01

    Using a Pt/Y3Fe5O12 (YIG) hybrid structure attached to a piezoelectric actuator, we demonstrate the generation of spin currents from sound waves. This "acoustic spin pumping" (ASP) is caused by the sound wave generated by the piezoelectric actuator, which then modulates the distribution function of magnons in the YIG layer and results in a pure-spin-current injection into the Pt layer across the Pt/YIG interface. In the Pt layer, this injected spin current is converted into an electric voltage due to the inverse spin-Hall effect (ISHE). The ISHE induced by the ASP is detected by measuring a voltage in the Pt layer at the piezoelectric resonance frequency of the actuator coupled with the Pt/YIG system. The frequency-dependent measurements enable us to separate the ASP-induced signals from extrinsic heating effects. Our model calculation based on the linear response theory provides us with a qualitative and quantitative understanding of the ASP in the Pt/YIG system.

  17. Ion heating, burnout of the HF field and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

    CERN Document Server

    Kirichok, A V; Pryimak, A V; Zagorodny, A G

    2015-01-01

    The development of one-dimensional parametric instabilities of intense long-wave plasma waves is considered in terms of the so-called hybrid models, when electrons are treated as a fluid and ions are 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 (LF) 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. Reduced absorption of the HF field leads to the retardation of the HF field burnout within plasma density cavities and to the broadening of the HF spectrum. At the same time, the i...

  18. Research on the static experiment of super heavy crude oil demulsification and dehydration using ultrasonic wave and audible sound wave at high temperatures.

    Science.gov (United States)

    Wang, Zhenjun; Gu, Simin; Zhou, Long

    2018-01-01

    In this paper, the static experiment of super heavy crude oil demulsification and dehydration using ultrasonic irradiation at high temperatures is carried out. How the all factors, such as ultrasonic frequency, sound intensity, ultrasonic power, ultrasonic treatment time, sedimentation time, temperature and water ratio, affect ultrasonic crude oil demulsification and dehydration are summarized though this experiment. In addition, recent progress on ultrasonic demulsification equipment in China are reviewed. The purpose of this paper is to provide equipment and technical support for the extensive application of the technique of ultrasonic demulsification and dehydration. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Completion and fracture modeling of low-permeability gas sand in south Texas enhanced by magnetic resonance and sound wave technology

    Energy Technology Data Exchange (ETDEWEB)

    Fairhurst, D. L.; Marfice, J. P. [Schlumberger Oilfield Services Inc (United States); Seim, M. R.; Norville, M. A. [Kerns Oil and Gas Inc (United States)

    2000-07-01

    Recent advances in well logging, which involve the application of sound wave forms and magnetic resonance technology and result in more accurate shear modulus and permeability estimates, are discussed. In some cases, use of magnetic resonance has identified previously bypassed permeable streaks that increased production. In others, sonic waveforms technology has helped determine fracture direction, which led to better gas drainage and well placement. The model incorporating these techniques has been found to produce good results for completions in the Olmos and San Miguel sands of south Texas. This paper presents comparisons between field data with model predictions to illustrate how use of the model can improve both productivity estimates as well as fracture design parameters for tight sand formations. 14 refs., 12 figs., 1 appendix.

  20. Electric Field Observations of Plasma Convection, Shear, Alfven Waves, and other Phenomena Observed on Sounding Rockets in the Cusp and Boundary Layer

    Science.gov (United States)

    Pfaff, R. F.

    2009-01-01

    On December 14,2002, a NASA Black Brant X sounding rocket was launched equatorward from Ny Alesund, Spitzbergen (79 N) into the dayside cusp and subsequently cut across the open/closed field line boundary, reaching an apogee of771 km. The launch occurred during Bz negative conditions with strong By negative that was changing during the flight. SuperDarn (CUTLASS) radar and subsequent model patterns reveal a strong westward/poleward convection, indicating that the rocket traversed a rotational reversal in the afternoon merging cell. The payload returned DC electric and magnetic fields, plasma waves, energetic particle, suprathermal electron and ion, and thermal plasma data. We provide an overview of the main observations and focus on the DC electric field results, comparing the measured E x B plasma drifts in detail with the CUTLASS radar observations of plasma drifts gathered simultaneously in the same volume. The in situ DC electric fields reveal steady poleward flows within the cusp with strong shears at the interface of the closed/open field lines and within the boundary layer. We use the observations to discuss ionospheric signatures of the open/closed character of the cusp/low latitude boundary layer as a function of the IMF. The electric field and plasma density data also reveal the presence of very strong plasma irregularities with a large range of scales (10 m to 10 km) that exist within the open field line cusp region yet disappear when the payload was equatorward of the cusp on closed field lines. These intense low frequency wave observations are consistent with strong scintillations observed on the ground at Ny Alesund during the flight. We present detailed wave characteristics and discuss them in terms of Alfven waves and static irregularities that pervade the cusp region at all altitudes.

  1. SU-E-J-138: On the Ion Beam Range and Dose Verification in Hadron Therapy Using Sound Waves

    Energy Technology Data Exchange (ETDEWEB)

    Fourkal, E [Fox Chase Cancer Center, Philadelphia, PA (United States); Allegheny General Hospital, Pittsburgh, PA (United States); Veltchev, I [Fox Chase Cancer Center, Philadelphia, PA (United States); Gayou, O [Allegheny General Hospital, Pittsburgh, PA (United States); Nahirnyak, V [Bukovinian State Medical University, Chernivtsi (Ukraine)

    2015-06-15

    Purpose: Accurate range verification is of great importance to fully exploit the potential benefits of ion beam therapies. Current research efforts on this topic include the use of PET imaging of induced activity, detection of emerging prompt gamma rays or secondary particles. It has also been suggested recently to detect the ultrasound waves emitted through the ion energy absorption process. The energy absorbed in a medium is dissipated as heat, followed by thermal expansion that leads to generation of acoustic waves. By using an array of ultrasound transducers the precise spatial location of the Bragg peak can be obtained. The shape and intensity of the emitted ultrasound pulse depend on several variables including the absorbed energy and the pulse length. The main objective of this work is to understand how the ultrasound wave amplitude and shape depend on the initial ion energy and intensity. This would help guide future experiments in ionoacoustic imaging. Methods: The absorbed energy density for protons and carbon ions of different energy and field sizes were obtained using Fluka Monte Carlo code. Subsequently, the system of coupled equations for temperature and pressure is solved for different ion pulse intensities and lengths to obtain the pressure wave shape, amplitude and spectral distribution. Results: The proposed calculations show that the excited pressure wave amplitude is proportional to the absorbed energy density and for longer ion pulses inversely proportional to the ion pulse duration. It is also shown that the resulting ionoacoustic pressure distribution depends on both ion pulse duration and time between the pulses. Conclusion: The Bragg peak localization using ionoacoustic signal may eventually lead to the development of an alternative imaging method with sub-millimeter resolution. It may also open a way for in-vivo dose verification from the measured acoustic signal.

  2. 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.

  3. 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.

  4. Study of the mechanism for broadening of the spectrum of a low-frequency reverberation signal for sound scattering by near-surface inhomogeneities under conditions of intense wind waves

    Science.gov (United States)

    Salin, B. M.; Kemarskaya, O. N.; Molchanov, P. A.; Salin, M. B.

    2017-05-01

    The paper considers the problem of backscattering of sound waves by near-surface volumetric inhomogeneities under conditions of intense wind waves. We calculate the expected share of the scattered signal spectrum based on the given wind-wave intensity and the depth distribution of volumetric inhomogeneities. For deep ocean conditions in the frequency range of 500-1000 Hz for a pulse duration of 10 s, we measure the levels and shape of the reverberation spectrum for time delays from 20 to 100 s. Comparison of the measured and calculated reverberation spectra has shown their good coincidence.

  5. 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...

  6. 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.

  7. 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....

  8. Gyrokinetic analysis of low-n shear Alfvén and ion sound wave spectra in a high-beta tokamak plasma

    Science.gov (United States)

    Bierwage, Andreas; Lauber, Philipp

    2017-11-01

    Using the linear gyrokinetic code LIGKA, we study the structure of the continuous spectra Ω(ρ) = ω(ρ) + iγ(ρ) of shear Alfvén waves (SAW) and ion sound waves (ISW) in a high-beta JT-60U tokamak plasma and look for evidence of Alfvén acoustic couplings or mode conversion. Here, Ω is the complex local eigenfrequency, ρ is a radial coordinate, and we consider waves with low toroidal mode number n=3 . We focus on the frequency range ω_BAE ≲ ω ≲ ω_TAE between the beta-induced and toroidicity-induced Alfvén frequency gaps. The real frequencies ω(ρ) of the gyrokinetic ISW continua are remarkably similar to MHD results. The kinetic damping rates are of order -γ/ω ∼ 30% for T_e/Ti ≈ 1.7 , and reduce to 15% when the temperature ratio is raised to T_e/Ti ≈ 4.8 . It is shown that SAW and ISW continua can be simultaneously excited with an antenna and that the global response of the ISWs is significantly enhanced when the on-axis beta value is raised from β0 = 1.7% to 3.6% while keeping T_e/Ti > 1 . In contrast, when the ion temperature is increased such that T_e/Ti ≈ 0.4 , ISW branches become undetectable in spite of higher β0 . At the same time, a large part of the SAW continuum is locally destabilized by ion temperature gradients and a set of discrete global modes was found, some of which are weakly damped or unstable and interpreted as kinetic beta-induced Alfvén eigenmodes. It is estimated that the kinetic damping of such low-n Alfvénic modes contributes much more to the anomalous bulk ion heating than the excitation of nearby ISW continua, so that Alfvén acoustic couplings in the frequency band ω_BAE ≲ ω ≲ ω_TAE are irrelevant within the scope of the model used.

  9. Anisotropy and sound propagation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1999-01-01

    Sound propagation in glass wool is studied theoretically and experimentally. Theoretical computation of attenuation and phase velocity for plane, harmonic waves will be presented. Glass wool is a highly anisotropic material, and sound waves propagating in different directions in the material...... by regarding it as a continuous medium described by its elastic moduli and mass density. The computed attenuation of sound waves, for frequencies 50–5000 Hz, will be compared with experimental results for glass wool with fiber diameters of 6.8 micrometers, mass density of 15 and 30 kg/m3, and elastic moduli...... of 2000 and 16 000 Pa (sound wave vector perpendicular to fibers)....

  10. 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...

  11. Statistics of Natural Binaural Sounds

    OpenAIRE

    Wiktor Młynarski; Jürgen Jost

    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....

  12. Natural statistics of binaural sounds

    OpenAIRE

    Młynarski, Wiktor; Jost, Jürgen

    2014-01-01

    Binaural sound localization is usually considered a discrimination task, where interaural time (ITD) and level (ILD) disparities at pure frequency channels are utilized to identify a position of a sound source. In natural conditions 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. In order to process...

  13. Entropic "sound" in the atmosphere

    OpenAIRE

    Apostol, B. -F.; Stefan, S.; Apostol, M.

    1996-01-01

    It is shown that small, local disturbances of entropy in the atmosphere may give rise to "sound" waves propagating with a velocity which depends on the amplitude ratio of the local relative variations of temperature and volume. This velocity is much smaller than the mean molecular velocity and the usual, adiabatic sound velocity.

  14. Electromagnetic theory of sound and phonons in liquid

    OpenAIRE

    Stupka, A. A.

    2016-01-01

    Sound waves in and dielectric liquid, that consists of subsystems of valency electrons with effective mass and ions which interact through the long-wave potential electric field are considered, on analogies with and metallic liquid, but with the requirement, that electric current is absent. It is shown that usual description of sound wave in an ideal liquid as wave of mass density and mass velocity follows from the offered consideration. It is also shown that sound waves with other side can b...

  15. 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....

  16. Photoacoustic Sounds from Meteors

    Science.gov (United States)

    Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, Gigi; Spurný, Pavel

    2017-02-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with -11 to -13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that -12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.

  17. 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

  18. 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....

  19. 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.

  20. Wind Turbine Noise and Natural Sounds : Masking, Propagation and Modeling

    OpenAIRE

    Bolin, Karl

    2009-01-01

    Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. Ambient sounds influence the audibility of wind turbine noise. Models for assessing two commonly occurring natural ambient sounds namely vegetation sound and sound from breaking waves are pres...

  1. Waves in inhomogeneous media

    NARCIS (Netherlands)

    Gerritsen, S.

    2007-01-01

    In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity

  2. 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

  3. 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...

  4. Controlling sound with acoustic metamaterials

    DEFF Research Database (Denmark)

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

    2016-01-01

    -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......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...

  5. Recent simulation techniques of viscous and thermal losses of sound waves in fluids and their applications in the micro-scale

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente

    2015-01-01

    In classical acoustics small devices in the scale of micrometers such as transducers, couplers or hearing aids are designed b experimentation. In the last 15 years or so, new numerical tools based on the Finite Element Method (FEM) and the Boundary Element Method describe sound fields with viscous...

  6. Sounds in the ocean at 1-100 Hz.

    Science.gov (United States)

    Wilcock, William S D; Stafford, Kathleen M; Andrew, Rex K; Odom, Robert I

    2014-01-01

    Very-low-frequency sounds between 1 and 100 Hz propagate large distances in the ocean sound channel. Weather conditions, earthquakes, marine mammals, and anthropogenic activities influence sound levels in this band. Weather-related sounds result from interactions between waves, bubbles entrained by breaking waves, and the deformation of sea ice. Earthquakes generate sound in geologically active regions, and earthquake T waves propagate throughout the oceans. Blue and fin whales generate long bouts of sounds near 20 Hz that can dominate regional ambient noise levels seasonally. Anthropogenic sound sources include ship propellers, energy extraction, and seismic air guns and have been growing steadily. The increasing availability of long-term records of ocean sound will provide new opportunities for a deeper understanding of natural and anthropogenic sound sources and potential interactions between them.

  7. 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....

  8. 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....

  9. 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...... investigates how the results relate to the modal theory of room acoustics, based on the conception that any mode, also in non-rectangular rooms, can be expanded into a number of propagating waves....

  10. 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.

  11. 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...

  12. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    OpenAIRE

    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 o...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...... 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...

  14. Sound settlements

    DEFF Research Database (Denmark)

    Duelund Mortensen, Peder

    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...

  15. Optimal Sound Absorbing Structures

    CERN Document Server

    Yang, Min; Fu, Caixing; Sheng, Ping

    2016-01-01

    Causal nature of the acoustic response, for any materials or structures, dictates an inequality that relates the absorption spectrum of the sample to its thickness. We present a general recipe for constructing sound-absorbing structures that can attain near-equality for the causal relation with very high absorption performance; such structures are denoted optimal. Our strategy involves using carefully designed acoustic metamaterials as backing to a thin layer of conventional sound absorbing material, e.g., acoustic sponge. By using this design approach, we have realized a 12 cm-thick structure that exhibits broadband, near-perfect flat absorption spectrum starting at around 400 Hz. From the causal relation, the calculated minimum sample thickness is 11.5 cm for the observed absorption spectrum. We present the theory that underlies such absorption performance, involving the evanescent waves and their interaction with a dissipative medium, and show the excellent agreement with the experiment.

  16. Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics

    Science.gov (United States)

    Stenzel, R. L.

    1978-01-01

    Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.

  17. 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....

  18. 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.

  19. 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.

  20. 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.

  1. Focusing of Finite-Amplitude Cylindrical and Spherical Sound Waves in a Viscous and Heat-Conducting Medium. Ph.D. Thesis

    Science.gov (United States)

    Chu, T.

    1971-01-01

    The focusing of acoustic pulses is studied analytically by considering the region of study in three parts: the converging, interaction and diverging regions. First, the linear problem of a pulse of infinitesimal amplitude is studied. For the spherical case, the expected phase change as a result of focusing is verified. The nonlinear case of finite-amplitude pulses leads to the development of M-waves, as determined by applying the method of matched-asymptotic expansions to Burges equation.

  2. A Numerical Study of the Regimes of Weak Fluctuation Theory for Ocean Acoustic Propagation through Random Internal Wave Sound Speed Fields

    Science.gov (United States)

    2007-03-01

    applied to a radio wave propagation problem in the atmosphere ( Jensen , Kuperman, Porter & Schmidt, 2000). The parabolic equation (PE) method has found...wide application in the field of underwater acoustics after Hardin and Tappert (1973) devised an efficient model based on Fourier transforms. The PE...equation follows the treatment by Jensen , Kuperman, Porter & Schmidt (2000). There are different kinds of parabolic equations, but this thesis

  3. Unidentified Sounds

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob

    2015-01-01

    , contextualised and conceptualised in an era of transmission. Observing that urban sounds until late 1930es are rarely heard in Danish radio compared to German and English broadcasting, I argue that an urban and auditory aesthetics incorporating noise, heterogeneity and unpredictability did not really develop......This article investigates how urban spaces and its noises are approached by radio reporters in the first decades of public radio production in Denmark. Focussing on the period before reel tape was incorporated in production by late 1940es, I ask how urban space and urban sounds are heard...... in Danish radio until early post-war years. Yet I trace early attempts at managing noisy urban conditions and demonstrate how reporters experimented with available technological repositories and developed techniques in order to make sense in and through urban environments. Inspired by Michel Serres idea...

  4. Making sound vortices by metasurfaces

    CERN Document Server

    Ye, Liping; Lu, Jiuyang; Tang, Kun; Jia, Han; Ke, Manzhu; Peng, Shasha; Liu, Zhengyou

    2016-01-01

    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.

  5. 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.

  6. 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.

  7. 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.

  8. Controlling sound with acoustic metamaterials

    Science.gov (United States)

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

    2016-03-01

    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 effective material properties that are not possible with passive structures and have led to the development of dynamically reconfigurable, loss-compensating and parity-time-symmetric materials for sound manipulation. Challenges remain, including the development of efficient techniques for fabricating large-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 of future directions in the field.

  9. 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...

  10. Reconstruction of sound fields with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Walton, Tim

    2014-01-01

    Spherical microphone arrays are very well suited for sound field measurements in enclosures or interior spaces, and generally in acoustic environments where sound waves impinge on the array from multiple directions. Because of their directional properties, they make it possible to resolve sound...... 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...

  11. Modified stethoscope for auscultation of temporomandibular joint sounds.

    Science.gov (United States)

    Dagar, Sanjiv Rajender Singh; Turakiya, Viral; Pakhan, Ashok J; Jaggi, Nitin; Kalra, Amit; Vaidya, Vidya

    2014-04-01

    Purpose of this study was to modify the stethoscope which can auscultate the temporomandibular joint (TMJ) sounds more precisely than conventional stethoscope, and fabrication of stethoscope compatible software which analyses the auscultated sound and gives documentary evidence of that analysis in the form of graph. The conventional stethoscope was modified by attaching a custom made soundscope with a recording device which can be placed in external auditory meatus (EAM) for auscultation of TMJ sounds. When this small and smooth end of custom made soundscope of modified stethoscope is placed in EAM & connected with specially developed software it records the TMJ sounds & analyzes them in form of graph. Fabrication of modified stethoscope with software records the auscultated sound as a sound wave in form of graph and analyses this sound wave graph to give graphic evidence of prominent intensity at prominent frequency as spectrum analysis graph, and duration of that sound as a sound length graph. The use of modified stethoscope with software increases the accuracy of auscultation of TMJ sounds without any patient's discomfort and helps in diagnosis of TMJ disorders. The modified stethoscope with software for auscultation of TMJ sounds results in more precise auscultation & analysis of TMJ for sounds even of low intensity & frequency. How to cite the article: Dagar SR, Turakiya V, Pakhan AJ, Jaggi N, Kalra A, Vaidya V. Modified stethoscope for auscultation of temporomandibular joint sounds. J Int Oral Health 2014;6(2):40-4.

  12. 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

  13. 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...

  14. Sound knowledge

    DEFF Research Database (Denmark)

    Kauffmann, Lene Teglhus

    The thesis is about the conceptualisation of knowledge associated with ‘evidence’. In the Danish society, there is a proliferating demand for ‘evidence’, which started as the basis of practices in medicine and has spread into social work, education and most policymaking arenas. The aim of the res......The thesis is about the conceptualisation of knowledge associated with ‘evidence’. In the Danish society, there is a proliferating demand for ‘evidence’, which started as the basis of practices in medicine and has spread into social work, education and most policymaking arenas. The aim...... 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...... 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...

  15. Sound ecologies

    Directory of Open Access Journals (Sweden)

    Duffy, Michelle

    2010-01-01

    Full Text Available Discussions about what constitutes ‘the rural’ invariably focus on notions of spatial location – of inhabiting spaces apart from that of the metropolitan. Deeply embedded in our images of what it means to be Australian, nonetheless our intellectual framing of ‘the rural’ as something outback and beyond has significant implications for our relations with these spaces. The relatively recent phenomenon of sea- and tree-changes has struck many unawares, and not simply because a good latté is so hard to find. Although a frivolous remark, such an apparent lack does shift our focus to a bodily scale of the rural; how is rural place re/made through our experiences of it? This article originates out of on-going research that explores the practice of listening and sound and the ways in which the body can draw attention to the intuitive, emotional, and psychoanalytical processes of subjectivity and place-making. Drawing on Nigel Thrift’s concept of an ecology of place, I suggest that contemporary heightened concerns with regards to loss and lack in rural Australia has led to a nascent emotional economy – one in which individual and intimate connections to the rural require a rethinking of how we live community and belonging. In such a terrain, what does it mean to be rural?

  16. Characterizing and Classifying Acoustical Ambient Sound Profiles

    Science.gov (United States)

    2015-03-26

    15 12 Threshold of Hearing for the Human Auditory System [2] . . . . . . . . . . . . 16 13 Complex Sound Wave [2...aircraft is heard by an observer, increasing our understanding of how ambient noise affects human hearing will lead to better capabilities in acoustic...noise emission con- sisted of “primarily insect noise and occasional birds”, and the high background noise emission consisted of “sounds of clothing

  17. Inhibition of Botrytis cinerea spore germination and mycelia growth by frequency-specific sound

    National Research Council Canada - National Science Library

    Jeong, Mi-Jeong; Bae, DongWon; Bae, Hanhong; Lee, Soo In; Kim, Jin A; Shin, Sung Chul; Park, Sung Han; Park, Soo-Chul

    2013-01-01

    The effect of sound waves on mycelial growth of Botrytis cinerea was investigated to explore whether frequency-specific sound could be used as a practical alternative to chemical fungicides to control plant diseases...

  18. Broadband sound pressure enhancement in passive metafluids

    Science.gov (United States)

    Popa, Bogdan-Ioan

    2017-09-01

    Acoustic sensors operating in lossy environments, such as water, require significant sensitivity to overcome the sound attenuation in the environment and thus see farther. We show here that a surprisingly large class of passive fluids has the ability to enhance the sound pressure propagating inside them without employing active actuation. Specifically, the general requirements for this remarkable property are fluid impedance higher than the impedance of the environment and negligible insertion loss as sound propagates from the environment into the high impedance fluid. We demonstrate the pressure enhancing effect by designing a broadband isotropic metafluid that increases the pressure of sound waves impinging from water. We validate the design in numerical simulations showing that significant sound pressure level increases are achievable in realistic metafluid structures in large bandwidths covering several octaves. Our approach opens up unexplored avenues towards improving acoustic transducer sensitivity, which is critical in applications, such as medical ultrasound imaging, sonar, and acoustic communications.

  19. Spatially extended sound equalization in rectangular rooms

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2001-01-01

    The results of a theoretical study on global sound equalization in rectangular rooms at low frequencies are presented. The zone where sound equalization can be obtained is a continuous three-dimensional region that occupies almost the complete volume of the room. It is proved that the equalization...... of broadband signals can be achieved by the simulation of a traveling plane wave using FIR filters. The optimal solution has been calculated following the traditional least-squares approximation, where a modeling delay has been applied to minimize reverberation. An advantage of the method is that the sound...

  20. Spatially extended sound equalization in rectangular rooms

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2001-01-01

    of broadband signals can be achieved by the simulation of a traveling plane wave using FIR filters. The optimal solution has been calculated following the traditional least-squares approximation, where a modeling delay has been applied to minimize reverberation. An advantage of the method is that the sound......The results of a theoretical study on global sound equalization in rectangular rooms at low frequencies are presented. The zone where sound equalization can be obtained is a continuous three-dimensional region that occupies almost the complete volume of the room. It is proved that the equalization...

  1. Laser Schlieren System Detects Sounds Of Leaks

    Science.gov (United States)

    Shakkottai, Parthasarathy P.; Alwar, A. Vijayaragavan

    1990-01-01

    Hostile environments monitored safely and noninvasively. Modified laser schlieren system acts as microphone to detect sounds of leaks remotely. Sensitive to acoustical frequencies above audible range and especially suited for monitoring leaks of high-pressure steam from boilers or chemical vapors from processing equipment. Does not require placement of delicate equipment in harsh environment monitored, and no contact needed with boiler or other unit being monitored. Detects sound waves via variation of index of refraction of air at acoustical frequencies. Used to monitor sound frequencies beyond range of human hearing.

  2. The warm, rich sound of valve guitar amplifiers

    Science.gov (United States)

    Keeports, David

    2017-03-01

    Practical solid state diodes and transistors have made glass valve technology nearly obsolete. Nevertheless, valves survive largely because electric guitar players much prefer the sound of valve amplifiers to the sound of transistor amplifiers. This paper discusses the introductory-level physics behind that preference. Overdriving an amplifier adds harmonics to an input sound. While a moderately overdriven valve amplifier produces strong even harmonics that enhance a sound, an overdriven transistor amplifier creates strong odd harmonics that can cause dissonance. The functioning of a triode valve explains its creation of even and odd harmonics. Music production software enables the examination of both the wave shape and the harmonic content of amplified sounds.

  3. Wind Turbine Noise and Natural Sounds: Masking, Propagation and Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Bolin, Karl

    2009-05-15

    Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. Ambient sounds influence the audibility of wind turbine noise. Models for assessing two commonly occurring natural ambient sounds namely vegetation sound and sound from breaking waves are presented in paper A and B. A sound propagation algorithm has been compared to long range measurements of sound propagation in paper C. Psycho-acoustic tests evaluating the threshold and partial loudness of wind turbine noise when mixed with natural ambient sounds have been performed. These are accounted for in paper D. The main scientific contributions are the following.Paper A: A semi-empiric prediction model for vegetation sound is proposed. This model uses up-to-date simulations of wind profiles and turbulent wind fields to estimate sound from vegetation. The fluctuations due to turbulence are satisfactory estimated by the model. Predictions of vegetation sound also show good agreement to measured spectra. Paper B: A set of measurements of air-borne sound from breaking waves are reported. From these measurements a prediction method of sound from breaking waves is proposed. Third octave spectra from breaking waves are shown to depend on breaker type. Satisfactory agreement between predictions and measurements has been achieved. Paper C: Long range sound propagation over a sea surface was investigated. Measurements of sound transmission were coordinated with local meteorological measurements. A sound propagation algorithm has been compared to the measured sound transmission. Satisfactory agreement between measurements and predictions were achieved when turbulence were taken into consideration in the computations. Paper D: The paper investigates the interaction between wind

  4. Sound absorption study of raw and expanded particulate vermiculites

    Science.gov (United States)

    Vašina, Martin; Plachá, Daniela; Mikeska, Marcel; Hružík, Lumír; Martynková, Gražyna Simha

    2016-12-01

    Expanded and raw vermiculite minerals were studied for their ability to absorb sound. Phase and structural characterization of the investigated vermiculites was found similar for both types, while morphology and surface properties vary. Sound waves reflect in wedge-like structure and get minimized, and later are absorbed totally. We found that thanks to porous character of expanded vermiculite the principle of absorption of sound into layered vermiculite morphology is analogous to principle of sound minimization in "anechoic chambers." It was found in this study that the best sound damping properties of the investigated vermiculites were in general obtained at higher powder bed heights and higher excitation frequencies.

  5. Multichannel Sound Reproduction

    Science.gov (United States)

    Pulkki, Ville

    Spatial reproduction of sound is a field in which the spatial attributes of a real recording room or a virtual space are reproduced to the listener. Spatial attributes include for example directions of sound sources, directions of reflections and envelopment by reverberation. Many such systems employ more than two loudspeakers to create virtual sources. This is called multichannel sound or spatial sound reproduction.

  6. Beyond Chemical Triggers: Evidence for Sound-Evoked Physiological Reactions in Plants

    Science.gov (United States)

    Jung, Jihye; Kim, Seon-Kyu; Kim, Joo Y.; Jeong, Mi-Jeong; Ryu, Choong-Min

    2018-01-01

    Sound is ubiquitous in nature. Recent evidence supports the notion that naturally occurring and artificially generated sound waves contribute to plant robustness. New information is emerging about the responses of plants to sound and the associated downstream signaling pathways. Here, beyond chemical triggers which can improve plant health by enhancing plant growth and resistance, we provide an overview of the latest findings, limitations, and potential applications of sound wave treatment as a physical trigger to modulate physiological traits and to confer an adaptive advantage in plants. We believe that sound wave treatment is a new trigger to help protect plants against unfavorable conditions and to maintain plant fitness. PMID:29441077

  7. Beyond Chemical Triggers: Evidence for Sound-Evoked Physiological Reactions in Plants

    Directory of Open Access Journals (Sweden)

    Jihye Jung

    2018-01-01

    Full Text Available Sound is ubiquitous in nature. Recent evidence supports the notion that naturally occurring and artificially generated sound waves contribute to plant robustness. New information is emerging about the responses of plants to sound and the associated downstream signaling pathways. Here, beyond chemical triggers which can improve plant health by enhancing plant growth and resistance, we provide an overview of the latest findings, limitations, and potential applications of sound wave treatment as a physical trigger to modulate physiological traits and to confer an adaptive advantage in plants. We believe that sound wave treatment is a new trigger to help protect plants against unfavorable conditions and to maintain plant fitness.

  8. Sound Propagation in the Atmosphere

    Science.gov (United States)

    Attenborough, Keith

    Propagation of sound close to the ground outdoors involves geometric spreading, air absorption, interaction with the ground, barriers, vegetation and refraction associated with wind and temperature gradients. After a brief survey of historical aspects of the study of outdoor sound and its applications, this chapter details the physical principles associated with various propagation effects, reviews data that demonstrate them and methods for predicting them. The discussion is concerned primarily with the relatively short ranges and spectra of interest when predicting and assessing community noise rather than the frequencies and long ranges of concern, for example, in infrasonic global monitoring or used for remote sensing of the atmosphere. Specific phenomena that are discussed include spreading losses, atmospheric absorption, diffraction by barriers and buildings, interaction of sound with the ground (ground waves, surface waves, ground impedance associated with porosity and roughness, and elasticity effects), propagation through crops, shrubs and trees, wind and temperature gradient effects, shadow zones and incoherence due to atmospheric turbulence. The chapter concludes by suggesting a few areas that require further research.

  9. 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

  10. 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

  11. Concurrent sound segregation is enhanced in musicians.

    Science.gov (United States)

    Zendel, Benjamin Rich; Alain, Claude

    2009-08-01

    The ability to segregate simultaneously occurring sounds is fundamental to auditory perception. Many studies have shown that musicians have enhanced auditory perceptual abilities; however, the impact of musical expertise on segregating concurrently occurring sounds is unknown. Therefore, we examined whether long-term musical training can improve listeners' ability to segregate sounds that occur simultaneously. Participants were presented with complex sounds that had either all harmonics in tune or the second harmonic mistuned by 1%, 2%, 4%, 8%, or 16% of its original value. The likelihood of hearing two sounds simultaneously increased with mistuning, and this effect was greater in musicians than nonmusicians. The segregation of the mistuned harmonic from the harmonic series was paralleled by an object-related negativity that was larger and peaked earlier in musicians. It also coincided with a late positive wave referred to as the P400 whose amplitude was larger in musicians than in nonmusicians. The behavioral and electrophysiological effects of musical expertise were specific to processing the mistuned harmonic as the N1, the N1c, and the P2 waves elicited by the tuned stimuli were comparable in both musicians and nonmusicians. These results demonstrate that listeners' ability to segregate concurrent sounds based on harmonicity is modulated by experience and provides a basis for further studies assessing the potential rehabilitative effects of musical training on solving complex scene analysis problems illustrated by the cocktail party example.

  12. Measuring the Speed of Sound through Gases Using Nitrocellulose

    Science.gov (United States)

    Molek, Karen Sinclair; Reyes, Karl A.; Burnette, Brandon A.; Stepherson, Jacob R.

    2015-01-01

    Measuring the heat capacity ratios, ?, of gases either through adiabatic expansion or sound velocity is a well established physical chemistry experiment. The most accurate experiments depend on an exact determination of sound origin, which necessitates the use of lasers or a wave generator, where time zero is based on an electrical trigger. Other…

  13. Sound Recordings and the Library. Occasional Papers Number 179.

    Science.gov (United States)

    Almquist, Sharon G.

    The basic concept that sound waves could be traced or recorded on a solid object was developed separately by Leon Scott, Charles Cros, and Thomas Alva Edison between 1857 and 1877 and, by 1890, the foundation of the present-day commercial record industry was established. Although cylinders were the first sound recordings to be sold commercially,…

  14. In situ sound absorption measurement: investigations on oblique incidence

    NARCIS (Netherlands)

    Kuipers, E.R.; Wijnant, Ysbrand H.; de Boer, Andries; Klemenz, M.

    2012-01-01

    A novel method for the measurement of sound absorption has been developed. By assuming that, in a single point, the sound field consists of an incident- and a reflected plane wave, the locally incident- and reflected intensities can be determined. To this purpose, the active intensity and the sum of

  15. Beaches and Bluffs of Puget Sound and the Northern Straits

    Science.gov (United States)

    2007-04-01

    all of which shape the health of salmon populations. Puget Sound and the Northern Straits encompass the cen- tral feature in the Puget Lowland...low-tide terrace (Figure 1). Lag deposits derived from bluff recession are often found in the low-tide terrace. Lag deposits are the largest clasts ...Strait of Juan de Fuca, Puget Sound area beaches are shaped by wind-generated waves. Wave energy is controlled by fetch: the open water distance

  16. 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...

  17. Synthesized size-sound sound symbolism

    NARCIS (Netherlands)

    Lockwood, G.F.; Hagoort, P.; Dingemanse, M.; Papafragou, A.; Grodner, D.; Mirman, D.; Trueswell, J.

    2016-01-01

    Studies of sound symbolism have shown that people can associate sound and meaning in consistent ways when presented with maximally contrastive stimulus pairs of nonwords such as bouba/kiki (rounded/sharp) or mil/mal (small/big). Recent work has shown the effect extends to antonymic words from

  18. Frequency and wavelength prediction of ultrasonic induced liquid surface waves.

    Science.gov (United States)

    Mahravan, Ehsan; Naderan, Hamid; Damangir, Ebrahim

    2016-12-01

    A theoretical investigation of parametric excitation of liquid free surface by a high frequency sound wave is preformed, using potential flow theory. Pressure and velocity distributions, resembling the sound wave, are applied to the free surface of the liquid. It is found that for impinging wave two distinct capillary frequencies will be excited: One of them is the same as the frequency of the sound wave, and the other is equal to the natural frequency corresponding to a wavenumber equal to the horizontal wavenumber of the sound wave. When the wave propagates in vertical direction, mathematical formulation leads to an equation, which has resonance frequency equal to half of the excitation frequency. This can explain an important contradiction between the frequency and the wavelength of capillary waves in the two cases of normal and inclined interaction of the sound wave and the free surface of the liquid. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. 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...

  20. 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....

  1. The Preparation of Microzonation Map of the Gulf of Buyukcekmece using results obtain by Vertical Electrical Sounding Measurements with Multi-Channel Analysis of Surface Wave and Microtremor Array Method

    Science.gov (United States)

    Tezel, Okan; Karabulut, Savas; Imre, Nazire; Caglak, Faruk; Yeziz, Hatice; Ozcep, Ferhat

    2013-04-01

    Istanbul is a megacity with 17 million inhabitants. After the 17 August 1999 earthquake, many researchers have focused on the mitigation of earthquake hazards in the Sea of Marmara and its vicinity. If we want to lessen the effects of such an earthquake, we have to learn about three different types of problems which are properties of the earthquake's source, whether of site effect or properties of engineering structures. When İstanbul Metropolitian Municipilaty obtained a World Bank Credit 5 years ago, they had a microzonation report for only a limited area which finished at Har amidere in the western site of Istanbul. Because they will not have any new project, the western side of Haramidere hasn't been studied by any scientist. For this reason, we focused on the Gulf of Buyukcekmece which is located on the western part of Haramidere and suffered in the 1999 earthquake. There are five geological units in the study area such as Bakirkoy formation, Gurpinar formation, Çukurçeşme formation, Güngören formation and Alluvial deposit. We conducted some measurements which are multi-channel analysis of surface wave (MASW), microtremor array method (MAM) and vertical electrical sounding(VES). The aim of using VES data is to determine bedrock depth, learn whether there is a new fault and learn the electrical properties of each layer of bedrock. The MASW method is so attactive, cheap and fast. According to seismic refraction, it has some advantages that are determining the deeper part of sub-surface, lower velocity layers and velocity contrast. Especially, we use natural sources; MAM methods are more useful method in the city. For all of these purposes, we collected MASW and MAM measurements at 80 sites and VES measurements at 20 sites. As primary results for VES measurements, we determined the bedrock depth by evaluating the VES measurements for the central, eastern and western part of Buyukcekmece Gulf. Bedrock depth is 308 meters in the central and eastern part of

  2. 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....

  3. Form Follows Sound

    OpenAIRE

    Caramiaux, Baptiste; Altavilla, Alessandro; Pobiner, Scott G.; Tanaka, Atau

    2015-01-01

    Sonic interaction is the continuous relationship between user actions and sound, mediated by some technology. Because interaction with sound may be task oriented or experience-based it is important to understand the nature of action-sound relationships in order to design rich sonic interactions. We propose a participatory approach to sonic interaction design that first considers the affordances of sounds in order to imagine embodied interaction, and based on this, generates interaction models...

  4. Sound radiation around a flying fly

    Science.gov (United States)

    Sueur, Jérôme; Tuck, Elizabeth J.; Robert, Daniel

    2005-07-01

    Many insects produce sounds during flight. These acoustic emissions result from the oscillation of the wings in air. To date, most studies have measured the frequency characteristics of flight sounds, leaving other acoustic characteristics-and their possible biological functions-unexplored. Here, using close-range acoustic recording, we describe both the directional radiation pattern and the detailed frequency composition of the sound produced by a tethered flying (Lucilia sericata). The flapping wings produce a sound wave consisting of a series of harmonics, the first harmonic occurring around 190 Hz. In the horizontal plane of the fly, the first harmonic shows a dipolelike amplitude distribution whereas the second harmonic shows a monopolelike radiation pattern. The first frequency component is dominant in front of the fly while the second harmonic is dominant at the sides. Sound with a broad frequency content, typical of that produced by wind, is also recorded at the back of the fly. This sound qualifies as pseudo-sound and results from the vortices generated during wing kinematics. Frequency and amplitude features may be used by flies in different behavioral contexts such as sexual communication, competitive communication, or navigation within the environment.

  5. Floquet topological insulators for sound

    Science.gov (United States)

    Fleury, Romain; Khanikaev, Alexander B; Alù, Andrea

    2016-01-01

    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. PMID:27312175

  6. Sound Radiation of Cylindrical Shells

    Directory of Open Access Journals (Sweden)

    B Alzahabi

    2016-09-01

    Full Text Available The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected. Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies. The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells. Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few. In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural, Longitudinal (axial, and Circumferential (torsional modes. In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t. It will be demonstrated that the noise radiation is a fluctuating pressure wave.

  7. Sound art and the annihilation of sound

    Science.gov (United States)

    Davies, Shaun

    This thesis describes the way in which sound is taken up and subsequently suppressed within the visual arts. The idealisation and development of sound as a plastic material is able to be traced within the modernist trajectory, which, reflecting a set of cultural practices and having developed its own specific terminologies, comes to regard any material, or anything conceived of as material, as appropriate and adequate to the expression of its distinctive and guiding concepts and metaphors. These concepts and metaphors are discussed as already having at their bases strongly visualist biases, the genealogies of which are traced within traditional or formal philosophies. Here, the marginalising tendency of ocularcentrism is exposed, but the very nature and contingency of marginalisation is found to work for the sound artist (where the perpetuation of the mythologised 'outsider' figure is desired) but against sound which is positioned in a purely differential and negative relation. In this epistemological and ontological reduction, sound becomes simply a visual metaphor or metonymic contraction which forecloses the possibility of producing other ways of articulating its experience or of producing any markedly alternative 'readings'. Rather than simply attempting to reverse the hierarchisation of the visual over the aural, or of prefacing sound within a range of artistic practices (each which would keep the negative tradition going) sound's ambiguous relation to the binarism of presence/absence, system and margin, is, however oddly, elaborated. The strategy which attempts to suspend sound primarily within and under the mark of the concept is interrogated and its limits exposed. The sound artist, the 'margin surfer' is revealed as a perhaps deeply conservative figure who may in the end desire the suppression of sound, and who, actually rejecting any destabilising and threatening notion of 'radical alterity' anxiously clings to the 'marginalised' modernist pretence. It is

  8. 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.......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...

  9. 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

  10. Identifying Students' Mental Models of Sound Propagation: The Role of Conceptual Blending in Understanding Conceptual Change

    Science.gov (United States)

    Hrepic, Zdeslav; Zollman, Dean A.; Rebello, N. Sanjay

    2010-01-01

    We investigated introductory physics students' mental models of sound propagation. We used a phenomenographic method to analyze the data in the study. In addition to the scientifically accepted Wave model, students used the "Entity" model to describe the propagation of sound. In this latter model sound is a self-standing entity,…

  11. Priming Gestures with Sounds.

    Science.gov (United States)

    Lemaitre, Guillaume; Heller, Laurie M; Navolio, Nicole; Zúñiga-Peñaranda, Nicolas

    2015-01-01

    We report a series of experiments about a little-studied type of compatibility effect between a stimulus and a response: the priming of manual gestures via sounds associated with these gestures. The goal was to investigate the plasticity of the gesture-sound associations mediating this type of priming. Five experiments used a primed choice-reaction task. Participants were cued by a stimulus to perform response gestures that produced response sounds; those sounds were also used as primes before the response cues. We compared arbitrary associations between gestures and sounds (key lifts and pure tones) created during the experiment (i.e. no pre-existing knowledge) with ecological associations corresponding to the structure of the world (tapping gestures and sounds, scraping gestures and sounds) learned through the entire life of the participant (thus existing prior to the experiment). Two results were found. First, the priming effect exists for ecological as well as arbitrary associations between gestures and sounds. Second, the priming effect is greatly reduced for ecologically existing associations and is eliminated for arbitrary associations when the response gesture stops producing the associated sounds. These results provide evidence that auditory-motor priming is mainly created by rapid learning of the association between sounds and the gestures that produce them. Auditory-motor priming is therefore mediated by short-term associations between gestures and sounds that can be readily reconfigured regardless of prior knowledge.

  12. Second Sound in Systems of One-Dimensional Fermions

    Science.gov (United States)

    Matveev, K. A.; Andreev, A. V.

    2017-12-01

    We study sound in Galilean invariant systems of one-dimensional fermions. At low temperatures, we find a broad range of frequencies in which in addition to the waves of density there is a second sound corresponding to the ballistic propagation of heat in the system. The damping of the second sound mode is weak, provided the frequency is large compared to a relaxation rate that is exponentially small at low temperatures. At lower frequencies, the second sound mode is damped, and the propagation of heat is diffusive.

  13. Spatial Sound and Multimodal Interaction in Immersive Environments

    DEFF Research Database (Denmark)

    Grani, Francesco; Overholt, Daniel; Erkut, Cumhur

    2015-01-01

    are discussed. These include elements in which we have provided sonic interaction in virtual environments, interactivity with volumetric sound sources using VBAP and Wave Field Synthesis (WFS), and binaural sound for virtual environments and spatial audio mixing. We show that the variety of approaches presented......Spatial sound and interactivity are key elements of investigation at the Sound And Music Computing master program at Aalborg University Copenhagen. We present a collection of research directions and recent results from work in these areas, with the focus on our multi- faceted approaches to two...

  14. Sound oscillation of dropwise cluster

    Energy Technology Data Exchange (ETDEWEB)

    Shavlov, A.V., E-mail: shavlov@ikz.ru [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation); Dzhumandzhi, V.A.; Romanyuk, S.N. [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation)

    2012-06-04

    There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10{sup 2}–10{sup 3} units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.

  15. 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...

  16. 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.

  17. Electrophysiological study of interaural sound intensity difference in the dolphin Inia geoffrensis.

    Science.gov (United States)

    Supin AYa; Popov, V V; Klishin, V O

    1991-09-15

    A wave observed in the auditory brainstem responses (ABR), sensitive to the side of sound presentation, is described in a dolphin (Inia geoffrensis). Dependence of the wave threshold on location of the sound source showed that the interaural intensity difference was more than 20 dB.

  18. A survey on the feasibility of sound classification on wireless sensor nodes

    NARCIS (Netherlands)

    Salomons, Etto; Havinga, Paul J.M.

    2015-01-01

    Wireless sensor networks are suitable to gain context awareness for indoor environments. As sound waves form a rich source of context information, equipping the nodes with microphones can be of great benefit. The algorithms to extract features from sound waves are often highly computationally

  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. Identifying students’ mental models of sound propagation: The role of conceptual blending in understanding conceptual change

    OpenAIRE

    Zdeslav Hrepic; Zollman, Dean A; N. Sanjay Rebello

    2010-01-01

    We investigated introductory physics students’ mental models of sound propagation. We used a phenomenographic method to analyze the data in the study. In addition to the scientifically accepted Wave model, students used the “Entity” model to describe the propagation of sound. In this latter model sound is a self-standing entity, different from the medium through which it propagates. All other observed alternative models contain elements of both Entity and Wave models, but at the same time are...

  1. Loudness of steady sounds - A new theory

    Science.gov (United States)

    Howes, W. L.

    1979-01-01

    A new mathematical theory for calculating the loudness of steady sounds from power summation and frequency interaction, based on psychoacoustic and physiological information, assuems that loudness is a subjective measure of the electrical energy transmitted along the auditory nerve to the central nervous system. The auditory system consists of the mechanical part modeled by a bandpass filter with a transfer function dependent on the sound pressure, and the electrical part where the signal is transformed into a half-wave reproduction represented by the electrical power in impulsive discharges transmitted along neurons comprising the auditory nerve. In the electrical part the neurons are distributed among artificial parallel channels with frequency bandwidths equal to 'critical bandwidths for loudness', within which loudness is constant for constant sound pressure. The total energy transmitted to the central nervous system is the sum of the energy transmitted in all channels, and the loudness is proportional to the square root of the total filtered sound energy distributed over all channels. The theory explains many psychoacoustic phenomena such as audible beats resulting from closely spaced tones, interaction of sound stimuli which affect the same neurons affecting loudness, and of individually subliminal sounds becoming audible if they lie within the same critical band.

  2. A sound future for acoustic metamaterials.

    Science.gov (United States)

    Cummer, Steven

    2017-05-01

    The field of acoustic metamaterials borrowed ideas from electromagnetics and optics to create engineered structures that exhibit desired fluid or fluid-like properties for the propagation of sound. These metamaterials offer the possibility of manipulating and controlling sound waves in ways that are challenging or impossible with conventional materials. Metamaterials with zero, or 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. And active acoustic metamaterials use external control and power to create effective material properties that are fundamentally not possible with passive structures. Challenges remain, including the development of efficient techniques for fabricating large-scale metamaterial structures and, critically, converting exciting laboratory experiments into practically useful devices. In this presentation, I will outline the recent history of the field, describe some of the designs and properties of materials with unusual acoustic parameters, discuss examples of extreme manipulation of sound, and finally, provide a personal perspective on future directions in the field.

  3. Sound field reconstruciton using a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    2016-01-01

    measurement area consisting of an array of spheres, and the sound field at any point of the source-free domain can be estimated, not being restricted to spherical surfaces. Because it is formulated as an elementary wave model, it allows for diverse solution strategies (least squares, ℓ1-norm minimization, etc......A method is presented that makes it possible to reconstruct an arbitrary sound field based on measurements with a spherical microphone array. The proposed method (spherical equivalent source method) makes use of a point source expansion to describe the sound field on the rigid spherical array, from...... which it is possible to reconstruct the sound field over a three-dimensional domain, inferring all acoustic quantities: sound pressure, particle velocity, and sound intensity. The problem is formulated using a Neumann Green's function that accounts for the presence of the rigid sphere in the medium. One...

  4. The forced sound transmission of finite single leaf walls using a variational technique

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2012-01-01

    , and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound......The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size...

  5. The sound of distance.

    Science.gov (United States)

    Rabaglia, Cristina D; Maglio, Sam J; Krehm, Madelaine; Seok, Jin H; Trope, Yaacov

    2016-07-01

    Human languages may be more than completely arbitrary symbolic systems. A growing literature supports sound symbolism, or the existence of consistent, intuitive relationships between speech sounds and specific concepts. Prior work establishes that these sound-to-meaning mappings can shape language-related judgments and decisions, but do their effects generalize beyond merely the linguistic and truly color how we navigate our environment? We examine this possibility, relating a predominant sound symbolic distinction (vowel frontness) to a novel associate (spatial proximity) in five studies. We show that changing one vowel in a label can influence estimations of distance, impacting judgment, perception, and action. The results (1) provide the first experimental support for a relationship between vowels and spatial distance and (2) demonstrate that sound-to-meaning mappings have outcomes that extend beyond just language and can - through a single sound - influence how we perceive and behave toward objects in the world. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. 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...

  7. 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...

  8. Orcas in Puget Sound

    Science.gov (United States)

    2007-01-01

    Washington. Mumford, T.F. 2007. Kelp and Eelgrass in Puget Sound. Puget Sound Nearshore Partnership Report No. 2007-05. Published by Seattle District, U.S...2006). Wild Chinook populations continue to decline due to dam con- struction, overall habitat loss , loss of prey and historical over-fishing...Sanford (2006) pointed out that current mean weight of adult Chinook salmon returning to their spawn- ing grounds in Puget Sound is only 56 percent of

  9. Interactively Evolving Compositional Sound Synthesis Networks

    DEFF Research Database (Denmark)

    Jónsson, Björn Þór; Hoover, Amy K.; Risi, Sebastian

    2015-01-01

    While the success of electronic music often relies on the uniqueness and quality of selected timbres, many musicians struggle with complicated and expensive equipment and techniques to create their desired sounds. Instead, this paper presents a technique for producing novel timbres that are evolved......, CPPNs can theoretically compute any function and can build on those present in traditional synthesizers (e.g. square, sawtooth, triangle, and sine waves functions) to produce completely novel timbres. Evolved with NeuroEvolution of Augmenting Topologies (NEAT), the aim of this paper is to explore...... the space of potential sounds that can be generated through such compositional sound synthesis networks (CSSNs). To study the effect of evolution on subjective appreciation, participants in a listener study ranked evolved timbres by personal preference, resulting in preferences skewed toward the first...

  10. Effort variation regularization in sound field reproduction

    DEFF Research Database (Denmark)

    Stefanakis, Nick; Jacobsen, Finn; Sarris, Ioannis

    2010-01-01

    . Specifically, it is suggested that the phase differential of the source driving signals should be in agreement with the phase differential of the desired sound pressure field. The performance of the suggested method is compared with that of conventional effort regularization, wave field synthesis (WFS......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...

  11. 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.

  12. 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

  13. Notes on Sound

    Directory of Open Access Journals (Sweden)

    Bonnie Jones

    2012-08-01

    Full Text Available Bonnie Jones creates improvised and composed text-sound performances that explore the fluidity and function of electronic noise (field recordings, circuit bending and text (poetry, found, spoken. She is interested in how people perceive, “read” and interact with these sounds and texts given our current technological moment.

  14. 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

  15. Shadow of sound

    OpenAIRE

    Prvacki, Ana

    2017-01-01

    Tiré du site Internet de Onestar Press: "Shadow of sound is a musical flip book, an attempt to move sound through pages and to measure music visually. Prvacki demonstrates that 40 seconds of Bach's Minuet in G Major fit on 150 pages.".

  16. 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...

  17. The sounds of nanotechnology

    Science.gov (United States)

    Campbell, Norah; Deane, Cormac; Murphy, Padraig

    2017-07-01

    Public perceptions of nanotechnology are shaped by sound in surprising ways. Our analysis of the audiovisual techniques employed by nanotechnology stakeholders shows that well-chosen sounds can help to win public trust, create value and convey the weird reality of objects on the nanoscale.

  18. 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...

  19. 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.

  20. Measurement of sound propagation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1995-01-01

    A new acoustic method for directly measuring the flow resistance, and the compressibility of fibrous materials such as glass wool, is given. Measured results for monochromatic sound in glass wool are presented and compared with theoretically calculated results. The agreement between experimental...... results and theory is good. Results of measurements of characteristic impedance, attenuation, and phase shift for plane monochromatic traveling waves are presented and compared with theoretically calculated ones. Good agreement between experimental and theoretical results was found....

  1. 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...

  2. Urban Sound Ecologies

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2013-01-01

    share the characteristics of site specificity. However, this article will consider the artwork in a broader context by re-examining how sound installations relate to the urban environment. For that purpose, this article brings together ecology terms from acoustic ecology of the sound theories...... of the 1970s while developing them into recent definitions of ecology in urban studies. Finally, we unfold our framing of urban sound ecologies with three case analyses: a sound intervention in Berlin, a symphony for wind instruments in Copenhagen and a video walk in a former railway station in Kassel....... The article concludes that the ways in which recent sound installations work with urban ecologies vary. While two of the examples blend into the urban environment, the other transfers the concert format and its mode of listening to urban space. Last, and in accordance with recent soundscape research, we point...

  3. Fiber movements and sound attenuation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1999-01-01

    Propagation of a plane harmonic sound wave in fiber materials such as glass wool is studied theoretically and experimentally. Wave equations are set up that take into account the movement of the fiber skeleton. The attenuation of the sound wave in slabs of glass wool was calculated and measured....... The main new result is that the experimental attenuation at low-frequency propagating wave is lower when the fibers move. For wave with frequency 100 Hz in glass wool of density 20 kg/m3, the attenuation of a layer of thickness 0.20 m is 4 dB if the fibers move, and 12 dB if they do not move...

  4. Tuning sound with soft dielectrics

    Science.gov (United States)

    Bortot, Eliana; Shmuel, Gal

    2017-04-01

    Soft dielectric tubes undergo large deformations when subjected to radial voltage. Using the theory of nonlinear electroelasticity, we investigate how voltage-controlled deformations of these tubes in an array alter acoustic wave propagation through it. We show that the propagation is annihilated across a certain audible frequency range, referred to as a sonic band gap. We carry out a numerical study, to find that the band gap depends nonlinearly on the voltage, owing to geometrical and material nonlinearities. By analyzing different mechanical constraints, we demonstrate that snap-through instabilities resulting from these nonlinearities can be harnessed to achieve sharp transitions in the gap width. Our conclusions hint at a new strategy to adaptively filter sound using a simple control parameter—an applied voltage.

  5. Einstein contra Aristotle: The sound from the heavens

    Science.gov (United States)

    Neves, J. C. S.

    2017-09-01

    In "On the Heavens" Aristotle criticizes the Pythagorean point of view which claims the existence of a cosmic music and a cosmic sound. According to the Pythagorean argument, there exists a cosmic music produced by stars and planets. These celestial bodies generate sound in its movements, and the music appears due to the cosmic harmony. For Aristotle, there is no sound produced by celestial bodies. Then, there is no music as well. However, recently, LIGO (Laser Interferometer Gravitational-Waves Observatory) has detected the gravitational waves predicted by Einstein. In some sense, a sound originated from black holes has been heard. That is, Einstein or the General Relativity and LIGO appear to be with the Pythagoreanism and against the master of the Lyceum.

  6. 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…

  7. 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.

  8. Categorization of environmental sounds.

    Science.gov (United States)

    Guastavino, Catherine

    2007-03-01

    This paper investigates the way in which people categorize environmental sounds in their everyday lives. Previous research has shown that isolated environmental sounds are categorized on the basis of high-level semantic features when the sounds can be attributed to specific sound sources. However, in the presence of numerous sound sources, as occur in most real-world situations, the process of source identification is often hindered. In the present study, a free categorization task with open-ended verbal descriptions was used to investigate auditory categories for environmental sounds in complex real-world sonic environments. Two main categories emerged from the free-sort, reflecting the absence or presence of human activity in relation to hedonic judgments. At a subordinate level, subcategories were mediated by the participant's reported interactions with the environment through socialized activities. The spontaneous verbal descriptors collected were successful in discriminating categories. These findings indicate that complex environmental sounds are processed and categorized as meaningful events providing relevant information about the environment. The relevance of situational factors in categorization and the notion of auditory category in its relation to linguistic labeling are then discussed.

  9. Sound as artifact

    Science.gov (United States)

    Benjamin, Jeffrey L.

    A distinguishing feature of the discipline of archaeology is its reliance upon sensory dependant investigation. As perceived by all of the senses, the felt environment is a unique area of archaeological knowledge. It is generally accepted that the emergence of industrial processes in the recent past has been accompanied by unprecedented sonic extremes. The work of environmental historians has provided ample evidence that the introduction of much of this unwanted sound, or "noise" was an area of contestation. More recent research in the history of sound has called for more nuanced distinctions than the noisy/quiet dichotomy. Acoustic archaeology tends to focus upon a reconstruction of sound producing instruments and spaces with a primary goal of ascertaining intentionality. Most archaeoacoustic research is focused on learning more about the sonic world of people within prehistoric timeframes while some research has been done on historic sites. In this thesis, by way of a meditation on industrial sound and the physical remains of the Quincy Mining Company blacksmith shop (Hancock, MI) in particular, I argue for an acceptance and inclusion of sound as artifact in and of itself. I am introducing the concept of an individual sound-form, or sonifact , as a reproducible, repeatable, representable physical entity, created by tangible, perhaps even visible, host-artifacts. A sonifact is a sound that endures through time, with negligible variability. Through the piecing together of historical and archaeological evidence, in this thesis I present a plausible sonifactual assemblage at the blacksmith shop in April 1916 as it may have been experienced by an individual traversing the vicinity on foot: an 'historic soundwalk.' The sensory apprehension of abandoned industrial sites is multi-faceted. In this thesis I hope to make the case for an acceptance of sound as a primary heritage value when thinking about the industrial past, and also for an increased awareness and acceptance

  10. Discovery of Sound in the Sea 2015 Annual Report

    Science.gov (United States)

    2015-09-30

    by peer-reviewed material available on the DOSITS website. It discusses the potential impacts that increased background noise and specific sound...renewable energy and the potential effects of noise produced by wind, wave, and tidal technologies. Another “Hot Topic” on ship noise and quieting...sounds added to the DOSITS Audio Gallery in the last year include underwater recordings of northern bottlenose whales, Lusitanian toadfish, submarine

  11. 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.

  12. Propagation of sound

    DEFF Research Database (Denmark)

    Wahlberg, Magnus; Larsen, Ole Næsbye

    2017-01-01

    As an acoustic signal travels from the source to a receiver, it is affected by a variety of physical processes, all dictated by properties of the signal and the environment. The signal energy is weakened by geometric attenuation as well as absorption by the medium. The temporal and spectral prope...... 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....

  13. Identification and modeling of internal waves

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.; Sadhuram, Y.; Rao, M.M.M.; SujithKumar, S.; Maneesha, K.; Sandhya, K.S.; Prakash, S.S.; Chandramouli, P.; Murthy, K.S.R.

    ,21pp823834. [6]MurthyP.G.KandG.R.KMurthy,1986:,?Acasestudyontheinfluenceof internal waves on sound propagation in the sea ?, Journal of Sound and Vibration,108(3),447 [7] Robinson. Allan.R. and Lee D., 1994 : ?Oceanography and Acoustics? AIP press...

  14. Ultrasonic waves in classical gases

    Science.gov (United States)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.

    2017-12-01

    The velocity and absorption coefficient for the plane sound waves in a classical gas are obtained by solving the Boltzmann kinetic equation, which describes the reaction of the single-particle distribution function to a periodic external field. Within the linear response theory, the nonperturbative dispersion equation valid for all sound frequencies is derived and solved numerically. The results are in agreement with the approximate analytical solutions found for both the frequent- and rare-collision regimes. These results are also in qualitative agreement with the experimental data for ultrasonic waves in dilute gases.

  15. Geometric phase mediated topological transport of sound vortices

    CERN Document Server

    Wang, Shubo; Chan, C T

    2016-01-01

    When a physical system undergoes a cyclic evolution, a non-integrable phase can arise in addition to the normal dynamical phase. This phase, depending only on the geometry of the path traversed in the parameter space and hence named geometric phase, has profound impact in both classical and quantum physics, leading to exotic phenomena such as electron weak anti-localization and light spin-Hall effect. Experimental observations of the geometric phase effect in classical system are typically realized using vector waves such as light characterized by a polarization. We show here that such an effect can also be realized in scalar wave systems such as sound wave. Using a helical hollow waveguide, we show that the geometric phase effect associated with the transportation of sound vortices, i.e. sound wave carrying intrinsic orbital angular momentum, can serve as a potential mechanism to control the flow of sound vortices with different topological charges, resulting in geometric phase-based sound vortex filters.

  16. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  17. Sound Art Situations

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2017-01-01

    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 productions 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...... 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...

  18. 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...

  19. 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....

  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. 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...

  2. Generation of sound zones in 2.5 dimensions

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Olsen, Martin; Møller, Martin

    2011-01-01

    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...... 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...

  3. Infrasound data inversion for atmospheric sounding

    Science.gov (United States)

    Lalande, J.-M.; Sèbe, O.; Landès, M.; Blanc-Benon, Ph.; Matoza, R. S.; Le Pichon, A.; Blanc, E.

    2012-07-01

    The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) continuously records acoustic waves in the 0.01-10 Hz frequency band, known as infrasound. These waves propagate through the layered structure of the atmosphere. Coherent infrasonic waves are produced by a variety of anthropogenic and natural sources and their propagation is controlled by spatiotemporal variations of temperature and wind velocity. Natural stratification of atmospheric properties (e.g. temperature, density and winds) forms waveguides, allowing long-range propagation of infrasound waves. However, atmospheric specifications used in infrasound propagation modelling suffer from lack and sparsity of available data above an altitude of 50 km. As infrasound can propagate in the upper atmosphere up to 120 km, we assume that infrasonic data could be used for sounding the atmosphere, analogous to the use of seismic data to infer solid Earth structure and the use of hydroacoustic data to infer oceanic structure. We therefore develop an inversion scheme for vertical atmospheric wind profiles in the framework of an iterative linear inversion. The forward problem is treated in the high-frequency approximation using a Hamiltonian formulation and complete first-order ray perturbation theory is developed to construct the Fréchet derivatives matrix. We introduce a specific parametrization for the unknown model parameters based on Principal Component Analysis. Finally, our algorithm is tested on synthetic data cases spanning different seasonal periods and network configurations. The results show that our approach is suitable for infrasound atmospheric sounding on a regional scale.

  4. 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

  5. Sound-Particles and Phonons with Spin 1

    Directory of Open Access Journals (Sweden)

    Samoilov V.

    2011-01-01

    Full Text Available We present a new model for solids which is based on the stimulated vibration of independent neutral Fermi-atoms, representing independent harmonic oscillators with natural frequencies, which are excited by actions of the longitudinal and transverse elastic waves. Due to application of the principle of elastic wave-particle duality, we predict that the lattice of a solid consists of two type Sound Boson-Particles with spin 1 with finite masses. Namely, these lattice Boson-Particles excite the longitudinal and transverse phonons with spin 1. In this letter, we estimate the masses of Sound Boson-Particles which are around 500 times smaller than the atom mass.

  6. Regularization in global sound equalization based on effort variation

    DEFF Research Database (Denmark)

    Stefanakis, Nick; Sarris, John; Jacobsen, Finn

    2009-01-01

    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....... 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...

  7. Mechanics, Waves and Thermodynamics

    Science.gov (United States)

    Ranjan Jain, Sudhir

    2016-05-01

    Figures; Preface; Acknowledgement; 1. Energy, mass, momentum; 2. Kinematics, Newton's laws of motion; 3. Circular motion; 4. The principle of least action; 5. Work and energy; 6. Mechanics of a system of particles; 7. Friction; 8. Impulse and collisions; 9. Central forces; 10. Dimensional analysis; 11. Oscillations; 12. Waves; 13. Sound of music; 14. Fluid mechanics; 15. Water waves; 16. The kinetic theory of gases; 17. Concepts and laws of thermodynamics; 18. Some applications of thermodynamics; 19. Basic ideas of statistical mechanics; Bibliography; Index.

  8. On the Sound Environment of the City of Puerto Vallarta, Jalisco, Mexico

    Directory of Open Access Journals (Sweden)

    R. R. Boullosa

    2011-12-01

    Full Text Available An exploration of the sound environment in the city of Puerto Vallarta, Jalisco, Mexico, is presented. A series of interviews were held with 19 residents, of which 7 were undergraduate students, related to the perception of sound in or around places of different zones in the so-called “Viejo Vallarta” (“Old Vallarta”.The purpose was twofold, firstly, to explore the ideas people have relating to the sounds they hear in the city -and in general, the ideas they have relating to peace and tranquility and its possible relation with the sound environment-; secondly, to identify some zones or places that have a particular sound environment - positive or negative. Natural sounds emerged as an important part of the sound identity of the Vallarta region and they seem to be highlyappreciated even when the sound levels are high. Sounds related to nature emerged in all interviews: bird calls, sound of wind rustling through trees, sound of breaking sea waves, etc. The interviewees identified places or zones with a negative sonic identity due to disagreeable or high intensity sounds; traffic flow, and mostly the urban bus, is to be blamed for in the main (some mentioned radios at high volume. A series of sound levels (dBA re 20 μPa at threedifferent times of the year: February, April, and October, 2009 were measured in some locations mentioned by the interviewees. The average sound levels found on those locations considered as having a disagreeable identity were the highest.

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

    Science.gov (United States)

    Jacobsen, Finn; Molares, Alfonso Rodríguez

    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 of high modal overlap, is extended to the region of low modal overlap by taking account of the random fluctuations of the sound power emitted by the source that generates the sound field. The validity of the extended model is confirmed by experimental and numerical results.

  10. Weak Anderson localisation in reverberation rooms and its effect on the uncertainty of sound power measurements

    DEFF Research Database (Denmark)

    Jacobsen, Finn

    2011-01-01

    The effect known as ‘weak Anderson localisation’, ‘coherent backscattering’ or ‘enhanced backscattering’ is a physical phenomenon that occurs in random systems, e.g., disordered media and linear wave systems, including reverberation rooms: the mean square response is increased at the drive point....... In a reverberation room this means that one can expect an increase of the reverberant sound field at the position of the source that generates the sound field. This affects the sound power output of the source and is therefore of practical concern. However, because of the stronger direct sound field at the source...... for the uncertainty of sound power measurements....

  11. 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...... of high modal overlap, is extended to the region of low modal overlap by taking account of the random fluctuations of the sound power emitted by the source that generates the sound field. The validity of the extended model is confirmed by experimental and numerical results....

  12. Acoustic wave propagation in Ni3 R (R = Mo, Nb, Ta) compounds

    Indian Academy of Sciences (India)

    Hence, when a sound wave travels at. 55. ◦ with the unique axis of these materials, the average sound velocity is found to be maximum. The results achieved are discussed and compared with the available experimental and theoretical results. Keywords. Elastic constants; longitudinal waves; surface waves; ultrasonic ...

  13. Wave scattering from statistically rough surfaces

    CERN Document Server

    Bass, F G; ter Haar, D

    2013-01-01

    Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a

  14. SOUND MORPHING BY FEATURE INTERPOLATION

    OpenAIRE

    Freitas Caetano, Marcelo; Rodet, Xavier

    2011-01-01

    International audience; The goal of sound morphing by feature interpolation is to obtain sounds whose values of features are intermediate between those of the source and target sounds. In order to do this, we should be able to resynthesize sounds that present a set of predefined feature values, a notoriously difficult problem. In this work, we present morphing techniques to obtain hybrid musical instrument sounds whose feature values correspond as close as possible to the ideal interpolated v...

  15. 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.

  16. Caustics of atmospheric waves

    Science.gov (United States)

    Godin, Oleg A.

    2015-04-01

    Much like light and sound, acoustic-gravity waves in inhomogeneous atmosphere often have a caustic or caustics, where the ray theory predicts unphysical, divergent values of the wave amplitude and needs to be modified. Increase of the wave magnitude in the vicinity of a caustic makes such vicinities of primary interest in a number of problems, where a signal needs to be separated from a background noise. The value of wave focusing near caustics should be carefully quantified in order to evaluate possible nonlinearities promoted by the focusing. Physical understanding of the wave field in the vicinity of a caustic is also important for understanding of the wave reflection from and transmission (tunneling) through the caustic. To our knowledge, in contrast to caustics of acoustic, electromagnetic, and seismic waves as well as gravity waves in incompressible fluids, asymptotics of acoustic-gravity waves in the vicinity of a caustic have never been studied systematically. In this paper, we fill this gap. Atmospheric waves are considered as linear acoustic-gravity waves in a neutral, horizontally stratified, moving ideal gas of variable composition. Air temperature and wind velocity are assumed to be gradually varying functions of height, and slowness of these variations determines the large parameter of the problem. The scale height of the atmosphere can be large or small compared to the vertical wavelength. It is found that the uniform asymptotics of the wave field in the presence of a simple caustic can be expressed in terms of the Airy function and its derivative. As for the acoustic waves, the argument of the Airy function is expressed in terms of the eikonal calculated in the ray, or WKB, approximation. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity waves, plays an important role in the caustic asymptotics. In the uniform asymptotics, the terms with the Airy function and its derivative are weighted by cosine

  17. 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.

  18. An Energy Budget Model to Calculate the Low Atmosphere Profiles of Effective Sound Speed at Night

    National Research Council Canada - National Science Library

    Tunick, Arnold

    2003-01-01

    ...) for generating low atmosphere profiles of effective sound speed at night. The alternate model is based on the solution of a quartic equation for surface temperature, which assumes a balance between the net long wave...

  19. 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

  20. 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 construction...... 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....

  1. 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...

  2. Direct Measurement of the Speed of Sound Using a Microphone and a Speaker

    Science.gov (United States)

    Gómez-Tejedor, José A.; Castro-Palacio, Juan C.; Monsoriu, Juan A.

    2014-01-01

    We present a simple and accurate experiment to obtain the speed of sound in air using a conventional speaker and a microphone connected to a computer. A free open source digital audio editor and recording computer software application allows determination of the time-of-flight of the wave for different distances, from which the speed of sound is…

  3. Understanding the Doppler Effect by Analysing Spectrograms of the Sound of a Passing Vehicle

    Science.gov (United States)

    Lubyako, Dmitry; Martinez-Piedra, Gordon; Ushenin, Arthur; Ushenin, Arthur; Denvir, Patrick; Dunlop, John; Hall, Alex; Le Roux, Gus; van Someren, Laurence; Weinberger, Harvey

    2017-01-01

    The purpose of this paper is to demonstrate how the Doppler effect can be analysed to deduce information about a moving source of sound waves. Specifically, we find the speed of a car and the distance of its closest approach to an observer using sound recordings from smartphones. A key focus of this paper is how this can be achieved in a…

  4. Sound pressure distribution within natural and artificial human ear canals: forward stimulation.

    Science.gov (United States)

    Ravicz, Michael E; Tao Cheng, Jeffrey; Rosowski, John J

    2014-12-01

    This work is part of a study of the interaction of sound pressure in the ear canal (EC) with tympanic membrane (TM) surface displacement. Sound pressures were measured with 0.5-2 mm spacing at three locations within the shortened natural EC or an artificial EC in human temporal bones: near the TM surface, within the tympanic ring plane, and in a plane transverse to the long axis of the EC. Sound pressure was also measured at 2-mm intervals along the long EC axis. The sound field is described well by the size and direction of planar sound pressure gradients, the location and orientation of standing-wave nodal lines, and the location of longitudinal standing waves along the EC axis. Standing-wave nodal lines perpendicular to the long EC axis are present on the TM surface >11-16 kHz in the natural or artificial EC. The range of sound pressures was larger in the tympanic ring plane than at the TM surface or in the transverse EC plane. Longitudinal standing-wave patterns were stretched. The tympanic-ring sound field is a useful approximation of the TM sound field, and the artificial EC approximates the natural EC.

  5. ABOUT SOUNDS IN VIDEO GAMES

    Directory of Open Access Journals (Sweden)

    Denikin Anton A.

    2012-12-01

    Full Text Available The article considers the aesthetical and practical possibilities for sounds (sound design in video games and interactive applications. Outlines the key features of the game sound, such as simulation, representativeness, interactivity, immersion, randomization, and audio-visuality. The author defines the basic terminology in study of game audio, as well as identifies significant aesthetic differences between film sounds and sounds in video game projects. It is an attempt to determine the techniques of art analysis for the approaches in study of video games including aesthetics of their sounds. The article offers a range of research methods, considering the video game scoring as a contemporary creative practice.

  6. Free Sixteen Harmonic Fourier Series Web App with Sound

    Science.gov (United States)

    Ruiz, Michael J.

    2018-01-01

    An online HTML5 Fourier synthesizer app is provided that allows students to manipulate sixteen harmonics and construct periodic waves. Students can set the amplitudes and phases for each harmonic, seeing the resulting waveforms and hearing the sounds. Five waveform presets are included: sine, triangle, square, ramp (sawtooth), and pulse train. The…

  7. On the excess attenuation of sound in the atmosphere

    Science.gov (United States)

    Deloach, R.

    1975-01-01

    The attenuation suffered by an acoustic plane wave propagating from an elevated source to the ground, in excess of absorption losses, was studied. Reported discrepancies between attenuation measurements made in the field and theories which only account for absorption losses are discussed. It was concluded that the scattering of sound by turbulence results in a nonnegligible contribution to the total attenuation.

  8. Measurements of anisotropic sound propagation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    2000-01-01

    The attenuation coefficient and phase velocity of plane sound waves propagating in three perpendicular directions in glass wool were measured in the frequency range 50–10 000 Hz. For glass wool of mass density 14 kg/m3 at the frequency 1000 Hz, the attenuation constant for propagation perpendicular...

  9. The Sounds of the Little and Big Bangs

    Science.gov (United States)

    Shuryak, Edward

    2017-11-01

    Studies of heavy ion collisions have discovered that tiny fireballs of new phase of matter -- quark gluon plasma (QGP) -- undergoes explosion, called the Little Bang. In spite of its small size, it is not only well described by hydrodynamics, but even small perturbations on top of the explosion turned to be well described by hydrodynamical sound modes. The cosmological Big Bang also went through phase transitions, the QCD and electroweak ones, which are expected to produce sounds as well. We discuss their subsequent evolution and hypothetical inverse acoustic cascade, amplifying the amplitude. Ultimately, collision of two sound waves leads to formation of gravity waves, with the smallest wavelength. We briefly discuss how those can be detected.

  10. Spatial filtering of audible sound with acoustic landscapes

    Science.gov (United States)

    Wang, Shuping; Tao, Jiancheng; Qiu, Xiaojun; Cheng, Jianchun

    2017-07-01

    Acoustic metasurfaces manipulate waves with specially designed structures and achieve properties that natural materials cannot offer. Similar surfaces work in audio frequency range as well and lead to marvelous acoustic phenomena that can be perceived by human ears. Being intrigued by the famous Maoshan Bugle phenomenon, we investigate large scale metasurfaces consisting of periodic steps of sizes comparable to the wavelength of audio frequency in both time and space domains. We propose a theoretical method to calculate the scattered sound field and find that periodic corrugated surfaces work as spatial filters and the frequency selective character can only be observed at the same side as the incident wave. The Maoshan Bugle phenomenon can be well explained with the method. Finally, we demonstrate that the proposed method can be used to design acoustical landscapes, which transform impulsive sound into famous trumpet solos or other melodious sound.

  11. Einstein contra Aristotle: the sound from the heavens

    CERN Document Server

    Neves, J C S

    2016-01-01

    In "On the Heavens" Aristotle criticizes the Pythagorean point of view which claims the existence of a cosmic music. According to the Pythagorean argument, there exists a cosmic music produced by stars and planets. These celestial bodies generate sound in its movements, and the music appears due to the cosmic harmony. For Aristotle, there is no sound produced by celestial bodies. Then, there is no music as well. However, recently, LIGO (Laser Interferometer Gravitational-Waves Observatory) has detected the gravitational waves predicted by Einstein. In some sense, a sound originated from black holes has been heard. That is, Einstein and LIGO appear to be with the Pythagoreanism and against the master of the Lyceum.

  12. Sounds in context

    DEFF Research Database (Denmark)

    Weed, Ethan

    are colored by contextual information. This can be longterm contextual information, such as knowledge of phonological or emotional categories, but can also be short-term local expectancies, such as the previous sound heard. In this paper, I present original electrophysiological data illustrating the early...

  13. Exploring Sound with Insects

    Science.gov (United States)

    Robertson, Laura; Meyer, John R.

    2010-01-01

    Differences in insect morphology and movement during singing provide a fascinating opportunity for students to investigate insects while learning about the characteristics of sound. In the activities described here, students use a free online computer software program to explore the songs of the major singing insects and experiment with making…

  14. See This Sound

    DEFF Research Database (Denmark)

    Kristensen, Thomas Bjørnsten

    2009-01-01

    Anmeldelse af udstillingen See This Sound på Lentos Kunstmuseum Linz, Østrig, som markerer den foreløbige kulmination på et samarbejde mellem Lentos Kunstmuseum og Ludwig Boltzmann Institute Media.Art.Research. Udover den konkrete udstilling er samarbejdet tænkt som en ambitiøs, tværfaglig unders...

  15. The Sounds of Metal

    DEFF Research Database (Denmark)

    Grund, Cynthia M.

    2015-01-01

    Two, I propose that this framework allows for at least a theoretical distinction between the way in which extreme metal – e.g. black metal, doom metal, funeral doom metal, death metal – relates to its sound as music and the way in which much other music may be conceived of as being constituted...

  16. 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 ...

  17. Neurobiology: Sounding the Alarm.

    Science.gov (United States)

    Belin, Pascal; Zatorre, Robert J

    2015-09-21

    Acoustical analysis has revealed a peculiar pattern of energy distribution in human screams; behavioral and neuroimaging data suggest that this pattern is associated with rapid and enhanced processing of sound cues signalling fear. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Sounds of the Desert.

    Science.gov (United States)

    McCullough-Brabson, Ellen; Achilles, Elayne; Ashcraft, Joan

    1997-01-01

    Discusses the program called "Sounds of the Desert" that celebrates the Southwest indigenous culture and focuses on understanding music in relation to history and culture. Emphasizes the study of Mariachi music that is being taught alongside band, orchestra, and chorus from the third grade to senior high in many Tucson (Arizona) schools.…

  19. 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...

  20. Urban Sound Ecologies

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2013-01-01

    . The article concludes that the ways in which recent sound installations work with urban ecologies vary. While two of the examples blend into the urban environment, the other transfers the concert format and its mode of listening to urban space. Last, and in accordance with recent soundscape research, we point...

  1. Making Sense of Sound

    Science.gov (United States)

    Menon, Deepika; Lankford, Deanna

    2016-01-01

    From the earliest days of their lives, children are exposed to all kinds of sound, from soft, comforting voices to the frightening rumble of thunder. Consequently, children develop their own naïve explanations largely based upon their experiences with phenomena encountered every day. When new information does not support existing conceptions,…

  2. Sound of Stockholm

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh

    2013-01-01

    Med sine kun 4 år bag sig er Sound of Stockholm relativt ny i det internationale festival-landskab. Festivalen er efter sigende udsprunget af en større eller mindre frustration over, at den svenske eksperimentelle musikscenes forskellige foreninger og organisationer gik hinanden bedene, og...

  3. The Universe of Sound

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    Sound Scultor, Bill Fontana, the second winner of the Prix Ars Electronica Collide@CERN residency award, and his science inspiration partner, CERN cosmologist Subodh Patil, present their work in art and science at the CERN Globe of Science and Innovation on 4 July 2013 at 19:00.

  4. MULTIMEDIA CARTOGRAPHY: MAPS WITH SOUND DESIGN AND SOUND MAPS

    OpenAIRE

    A. A. Medvedev

    2013-01-01

     Today,sound maps is not so popular like other and not so interested for social oriented projects. Basically only these typesof thematic maps are use sound like the way of representation: political, zoogeographical, vegetation, ethnographic isthe most meeting application of sound registration to maps. In this article a new way of presenting the terrain with sound that is designed for interactive maps with audio support for disabled people is described. The method is based on a comparison betw...

  5. Sound radiation from a fluid-loaded infinite plate with a patch.

    Science.gov (United States)

    Zhang, Yanni; Pan, Jie

    2013-01-01

    This paper focuses on the solution to the vibro-acoustic response of a line-driven fluid-loaded plate with an elastic patch acting as a distributed inhomogeneity. The patch affects the plate's sound radiation by adding extra loading to the driving force and by scattering structural waves. When the driving force is located beneath the patch, the extra loading reduces the plate's supersonic velocity response and sound radiation. At some frequencies, however, the constructive superposition of scattered structural waves and near-field waves by the driving force outweighs the effect of patch loading and results in an increased sound radiation power. When the patch is located away from the driving force, wave scattering phenomena dominates the plate vibration and subsequent sound radiation. By examining the effect of the length and location of the patch on the sound power, it is possible to relate the changes in the sound power to the changes in supersonic velocity spectrum and velocity distribution contributed by the trapped modes in the patched area and interference between the scattered waves by the patch and the near- and far-field structural waves directly generated by the driving force.

  6. Design and implementation of an underwater sound recording device

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jayson J.; Myers, Joshua R.; Carlson, Thomas J.; Deng, Zhiqun; Rohrer, John S.; Caviggia, Kurt A.

    2011-09-19

    The purpose of this study was to design and build two versions of an underwater sound recording device. The device designed is referred to as the Underwater Sound Recorder (USR), which can be connected to one or two hydrophones or other underwater sound sensors. The URS contains a 26 dB preamplifier and a user selectable gain that permits additional amplification of input to the system from 26 dB to 46 dB. Signals within the frequency range up to 15 kHz may be recorded using the USR. Examples of USR applications are monitoring underwater processes that have the potential to create large pressure waves that could potentially harm fish or other aquatic life, such as underwater explosions or pile driving. Additional applications are recording sound generated by vessels or the vocalizations of some marine mammals, such as the calls from many species of whales.

  7. Sound radiation in atmosphere during underwater earthquake

    Science.gov (United States)

    Vdovichenko, S. P.; Zaslavskiy, Y. M.

    1986-01-01

    Acoustic fields in the atmosphere generated by hydroacoustic disturbances which are caused by seismic movements of bottom rocks during an underwater earthquake are used to predict tsunami waves. Different models of deepened seismic sources equivalent to an earthquake focus with respect to the total quantity of released energy are outlined. The characteristics of radiation introduced by the ocean water layer are examined. The dependence of the level and directional diagram of radiation of focal depth is examined. The level of acoustic oscillations is examined at the maximum of the diagram at altitudes were the appearance of ionized regions detectable during sounding by Doppler radars is possible.

  8. Phononic crystals bring sound to a focus

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Dehesa, Jose

    2004-09-01

    Three years ago researchers at the University of California at San Diego created a storm in the world of optics when they announced that they had made a material that exhibited negative refraction. Light rays entering such a 'negative index' material are not bent towards the normal -- as happens in all known materials in nature -- but beyond the normal. Now physicists in China and Canada have demonstrated the equivalent phenomenon with sound waves in a material known as a 'phononic crystal'. (U.K.)

  9. Geoacoustic inversion using combustive sound source signals.

    Science.gov (United States)

    Potty, Gopu R; Miller, James H; Wilson, Preston S; Lynch, James F; Newhall, Arthur

    2008-09-01

    Combustive sound source (CSS) data collected on single hydrophone receiving units, in water depths ranging from 65 to 110 m, during the Shallow Water 2006 experiment clearly show modal dispersion effects and are suitable for modal geoacoustic inversions. CSS shots were set off at 26 m depth in 100 m of water. The inversions performed are based on an iterative scheme using dispersion-based short time Fourier transform in which each time-frequency tiling is adaptively rotated in the time-frequency plane, depending on the local wave dispersion. Results of the inversions are found to compare favorably to local core data.

  10. The Britannica Guide to Sound and Light

    CERN Document Server

    2010-01-01

    Audio and visual cues facilitate some of our most powerful sensory experiences and embed themselves deeply into our memories and subconscious. Sound and light waves interact with our ears and eyes?our biological interpreters?creating a textural experience and relationship with the world around us. This well-researched volume explores the science behind acoustics and optics and the broad application they have to everything from listening to music and watching television to ultrasonic and laser technologies that are crucial to the medical field.

  11. Auditory perception of self-similarity in water sounds.

    Directory of Open Access Journals (Sweden)

    Maria Neimark Geffen

    2011-05-01

    Full Text Available Many natural signals, including environmental sounds, exhibit scale-invariant statistics: their structure is repeated at multiple scales. Such scale invariance has been identified separately across spectral and temporal correlations of natural sounds (Clarke and Voss, 1975; Attias and Schreiner, 1997; Escabi et al., 2003; Singh and Theunissen, 2003. Yet the role of scale-invariance across overall spectro-temporal structure of the sound has not been explored directly in auditory perception. Here, we identify that the sound wave of a recording of running water is a self-similar fractal, exhibiting scale-invariance not only within spectral channels, but also across the full spectral bandwidth. The auditory perception of the water sound did not change with its scale. We tested the role of scale-invariance in perception by using an artificial sound, which could be rendered scale-invariant. We generated a random chirp stimulus: an auditory signal controlled by two parameters, Q, controlling the relative, and r, controlling the absolute, temporal structure of the sound. Imposing scale-invariant statistics on the artificial sound was required for its perception as natural and water-like. Further, Q had to be restricted to a specific range for the sound to be perceived as natural. To detect self-similarity in the water sound, and identify Q, the auditory system needs to process the temporal dynamics of the waveform across spectral bands in terms of the number of cycles, rather than absolute timing. We propose a two-stage neural model implementing this computation. This computation may be carried out by circuits of neurons in the auditory cortex. The set of auditory stimuli developed in this study are particularly suitable for measurements of response properties of neurons in the auditory pathway, allowing for quantification of the effects of varying the statistics of the spectro-temporal statistical structure of the stimulus.

  12. 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.

  13. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  14. Sound Insulation Property Study on Nylon 66 Scrim Reinforced PVF Laminated Membranes and their Composite Sound Proof Structure

    Science.gov (United States)

    Chen, Lihe; Chen, Zhaofeng; Zhang, Xinyang; Wang, Weiwei

    2018-01-01

    In this paper, we investigated the sound insulation property of nylon 66 scrim reinforced PVF laminated membranes and their corresponding composite structures with glass fiber felt and carbon fiber board. Sound transmission loss (STL) was measured by standing wave tube method. The results show that, with the decrease of nylon 66 gridlines spacing, STL of nylon 66 scrim reinforced PVF laminated membranes was improved. The sound insulation performance of laminated membranes with gridlines spacing of 3mm is the best, whose STL was up to 10dB at 6.3 kHz. Besides, STL was improved effectively as air layers were embedded into the composite sound proof construction consist of laminated membrane, glass fiber felt and carbon fiber board.

  15. Product sounds : Fundamentals and application

    NARCIS (Netherlands)

    Ozcan-Vieira, E.

    2008-01-01

    Products are ubiquitous, so are the sounds emitted by products. Product sounds influence our reasoning, emotional state, purchase decisions, preference, and expectations regarding the product and the product's performance. Thus, auditory experience elicited by product sounds may not be just about

  16. Data sonification and sound visualization.

    Energy Technology Data Exchange (ETDEWEB)

    Kaper, H. G.; Tipei, S.; Wiebel, E.; Mathematics and Computer Science; Univ. of Illinois

    1999-07-01

    Sound can help us explore and analyze complex data sets in scientific computing. The authors describe a digital instrument for additive sound synthesis (Diass) and a program to visualize sounds in a virtual reality environment (M4Cave). Both are part of a comprehensive music composition environment that includes additional software for computer-assisted composition and automatic music notation.

  17. Sonic mediations: body, sound, technology

    NARCIS (Netherlands)

    Birdsall, C.; Enns, A.

    2008-01-01

    Sonic Mediations: Body, Sound, Technology is a collection of original essays that represents an invaluable contribution to the burgeoning field of sound studies. While sound is often posited as having a bridging function, as a passive in-between, this volume invites readers to rethink the concept of

  18. Dual Waves

    OpenAIRE

    Kallosh, Renata

    1994-01-01

    We study the gravitational waves in the 10-dimensional target space of the superstring theory. Some of these waves have unbroken supersymmetries. They consist of Brinkmann metric and of a 2-form field. Sigma-model duality is applied to such waves. The corresponding solutions we call dual partners of gravitational waves, or dual waves. Some of these dual waves upon Kaluza-Klein dimensional reduction to 4 dimensions become equivalent to the conformo-stationary solutions of axion-dilaton gravity...

  19. A numerical method for determining the radial wave motion correction in plane wave couplers

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Torras Rosell, Antoni

    2016-01-01

    Microphones are used for realising the unit of sound pressure level, the pascal (Pa). Electro-acoustic reciprocity is the preferred method for the absolute determination of the sensitivity. This method can be applied in different sound fields: uniform pressure, free field or diffuse field. Pressure...... solution is an analytical expression that estimates the difference between the ideal plane wave sound field and a more complex lossless sound field created by a non-planar movement of the microphone’s membranes. Alternatively, a correction may be calculated numerically by introducing a full model...

  20. Sound spectral analysis of voice-transmitted sound.

    Science.gov (United States)

    Baughman, R P; Loudon, R G

    1986-07-01

    There is a change in voice-generated sound heard over an area of pulmonary consolidation described as the "e" to "a" change. The lung may act as a low pass filter with properties that are changed by consolidation. We studied 5 patients with pneumonia. Using an electronic stethoscope, we recorded the voice-generated sounds "e" and "9-9-9." Sound spectral analysis using the fast Fourier transformation technique was used to characterize the frequency spectrum of the recorded sound. This technique allowed us to evaluate the filter properties of the normal and consolidated lung. We found that the normal lung allowed transmission of sound as high as 250 Hz with a gradual cutoff by 400 Hz. The consolidated lung allowed transmission of sound of a higher frequency; however, there was no significant transmission of sound with a frequency higher than 1,000 Hz.

  1. Arrangements of a pair of loudspeakers for sound field control with double-layer arrays

    DEFF Research Database (Denmark)

    Chang, Jiho; Agerkvist, Finn T.; Olsen, Martin

    2013-01-01

    Recent studies have attempted to control sound fields, and also to reduce room reflections with a circular or spherical array of loudspeakers. One of the attempts was to suppress sound waves propagating to the walls outside the array with a circular double-layer array of loudspeakers. The double....... In order to solve this problem, this study aims to examine several arrangements of a pair of loudspeakers that has a short distance between the acoustic centres. The effect of diffraction of sound waves due to the enclosure of another loudspeaker is investigated in simulations in terms of the position...

  2. Sound for Health

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    From astronomy to biomedical sciences: music and sound as tools for scientific investigation Music and science are probably two of the most intrinsically linked disciplines in the spectrum of human knowledge. Science and technology have revolutionised the way artists work, interact, and create. The impact of innovative materials, new communication media, more powerful computers, and faster networks on the creative process is evident: we all can become artists in the digital era. What is less known, is that arts, and music in particular, are having a profound impact the way scientists operate, and think. From the early experiments by Kepler to the modern data sonification applications in medicine – sound and music are playing an increasingly crucial role in supporting science and driving innovation. In this talk. Dr. Domenico Vicinanza will be highlighting the complementarity and the natural synergy between music and science, with specific reference to biomedical sciences. Dr. Vicinanza will take t...

  3. Pitch Based Sound Classification

    DEFF Research Database (Denmark)

    Nielsen, Andreas Brinch; Hansen, Lars Kai; Kjems, U

    2006-01-01

    -max output function. Both linear and quadratic inputs are used. The model is trained on 2 hours of sound and tested on publicly available data. A test classification error below 0.05 with 1 s classification windows is achieved. Further more it is shown that linear input performs as well as a quadratic......A sound classification model is presented that can classify signals into music, noise and speech. The model extracts the pitch of the signal using the harmonic product spectrum. Based on the pitch estimate and a pitch error measure, features are created and used in a probabilistic model with soft......, and that even though classification gets marginally better, not much is achieved by increasing the window size beyond 1 s....

  4. Synchronization of sound sources.

    Science.gov (United States)

    Abel, Markus; Ahnert, Karsten; Bergweiler, Steffen

    2009-09-11

    Sound generation and interaction are highly complex, nonlinear, and self-organized. Nearly 150 years ago Rayleigh raised the following problem: two nearby organ pipes of different fundamental frequencies sound together almost inaudibly with identical pitch. This effect is now understood qualitatively by modern synchronization theory M. Abel et al. [J. Acoust. Soc. Am. 119, 2467 (2006)10.1121/1.2170441]. For a detailed investigation, we substituted one pipe by an electric speaker. We observe that even minute driving signals force the pipe to synchronization, thus yielding three decades of synchronization-the largest range ever measured to our knowledge. Furthermore, a mutual silencing of the pipe is found, which can be explained by self-organized oscillations, of use for novel methods of noise abatement. Finally, we develop a reconstruction method which yields a perfect quantitative match of experiment and theory.

  5. Synchronization of Sound Sources

    Science.gov (United States)

    Abel, Markus; Ahnert, Karsten; Bergweiler, Steffen

    2009-09-01

    Sound generation and interaction are highly complex, nonlinear, and self-organized. Nearly 150 years ago Rayleigh raised the following problem: two nearby organ pipes of different fundamental frequencies sound together almost inaudibly with identical pitch. This effect is now understood qualitatively by modern synchronization theory M. Abel et al. [J. Acoust. Soc. Am. 119, 2467 (2006)JASMAN0001-496610.1121/1.2170441]. For a detailed investigation, we substituted one pipe by an electric speaker. We observe that even minute driving signals force the pipe to synchronization, thus yielding three decades of synchronization—the largest range ever measured to our knowledge. Furthermore, a mutual silencing of the pipe is found, which can be explained by self-organized oscillations, of use for novel methods of noise abatement. Finally, we develop a reconstruction method which yields a perfect quantitative match of experiment and theory.

  6. Sound in Ergonomics

    Directory of Open Access Journals (Sweden)

    Jebreil Seraji

    1999-03-01

    Full Text Available The word of “Ergonomics “is composed of two separate parts: “Ergo” and” Nomos” and means the Human Factors Engineering. Indeed, Ergonomics (or human factors is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. It has applied different sciences such as Anatomy and physiology, anthropometry, engineering, psychology, biophysics and biochemistry from different ergonomics purposes. Sound when is referred as noise pollution can affect such balance in human life. The industrial noise caused by factories, traffic jam, media, and modern human activity can affect the health of the society.Here we are aimed at discussing sound from an ergonomic point of view.

  7. 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 ......, and can therefore be utilized outside the laboratory setting. A first experimental evaluation indicates that the device can effectively modulate the perception of the ground surface during walking, thereby, inducing changes in the gait of healthy subjects....

  8. 46 CFR 7.20 - Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island Sound and...

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island Sound and easterly entrance to Long Island Sound, NY. 7.20 Section 7.20... Atlantic Coast § 7.20 Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island...

  9. Synaesthetic metaphors and sound

    Directory of Open Access Journals (Sweden)

    Jerneja Primožič

    2017-12-01

    Full Text Available This paper analyses a phenomenon called synaesthetic metaphors, in which one sensory modality is described in terms of another (e.g. bright sound, sharp taste, sweet smell. The aim of the research, based on the contrastive analysis of Slovenian and French music reviews, is to determine which sense domains are employed for (synaesthetic description of sound, more precisely music, and how frequent they are. In this regard the paper examines the directionality principle according to which more concrete and more accessible lower senses (touch, taste, smell tend to map onto less concrete and less accessible higher senses (sound, sight. Furthermore, the analysis focuses on two other aspects: the conventionality of synaesthetic metaphors and their connotative meaning. Since the source and target domain in synaesthetic transfers belong to sense domains, the paper emphasizes the experiential – i.e. perceptive, cognitive, and sociocultural – dimension of this phenomenon, with regard to which rises the main question concerning the universal and cultural tendencies of synaesthetic metaphors.

  10. Root phonotropism: Early signalling events following sound perception in Arabidopsis roots.

    Science.gov (United States)

    Rodrigo-Moreno, Ana; Bazihizina, Nadia; Azzarello, Elisa; Masi, Elisa; Tran, Daniel; Bouteau, François; Baluska, Frantisek; Mancuso, Stefano

    2017-11-01

    Sound is a fundamental form of energy and it has been suggested that plants can make use of acoustic cues to obtain information regarding their environments and alter and fine-tune their growth and development. Despite an increasing body of evidence indicating that it can influence plant growth and physiology, many questions concerning the effect of sound waves on plant growth and the underlying signalling mechanisms remains unknown. Here we show that in Arabidopsis thaliana, exposure to sound waves (200Hz) for 2 weeks induced positive phonotropism in roots, which grew towards to sound source. We found that sound waves triggered very quickly (within  minutes) an increase in cytosolic Ca 2+ , possibly mediated by an influx through plasma membrane and a release from internal stock. Sound waves likewise elicited rapid reactive oxygen species (ROS) production and K + efflux. Taken together these results suggest that changes in ion fluxes (Ca 2+ and K + ) and an increase in superoxide production are involved in sound perception in plants, as previously established in animals. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Features of sound refraction in the atmosphere in fog

    Science.gov (United States)

    Shagapov, V. Sh.; Sarapulova, V. V.

    2014-11-01

    The reflection and refraction of acoustic waves at the air-fog interface are considered. The phase velocity and the coefficient of sound damping for fog, as well as the reflection and refraction coefficients at normal and oblique incidences of a wave, are calculated. A dependence of the refraction angle on a frequency and the angle of acoustic wave incidence on the air-mist interface is studied. Based on the analytical expressions obtained and the analysis of numerical calculations, it is established that if a wave is incident from fog to the interface there is a critical angle of incidence so that total internal reflection occurs at greater angles. It is shown that the total internal reflection does not occur when a wave is incident from air on the air-fog interface.

  12. Feedback control of sound

    Science.gov (United States)

    Rafaely, Boaz

    This thesis is concerned with the development an application of feedback control techniques for active sound control. Both fixed and adaptive controllers are considered. The controller design problem for active sound control is formulated as a constrained optimisation problem with an H2 performance objective, of minimising the variance of the control error, and H2 and H∞ design constraints involving control power output, disturbance enhancement, and robust stability. An Internal Model Controller with an FIR control filter is assumed. Conventional H2 design methods for feedback controllers are studied first. Although such controllers can satisfy the design constraints by employing effort terms in the quadratic cost function, they do not achieve the best possible performance, and when adapted using LMS-based algorithms, they suffer from instabilities if the plant response varies significantly. Improved H2/H∞ design methods for fixed and adaptive controllers are then developed, which achieve the best H2 performance under the design constraints, offer an improved stability when made adaptive, and in general outperform the conventional H2 controllers. The H2/H∞ design problems employ convex programming to ensure a unique solution. The Sequential Quadratic Programming methods is used for the off-line design of fixed controllers, and penalty and barrier function methods, together with frequency domain LMS-based algorithms are employed in the H2/H∞ adaptive controllers. The controllers studied and developed here were applied to three active sound control systems: a noise-reducing headset, an active headrest, and a sound radiating panel. The emphasis was put on developing control strategies that improve system performance. First, a high performance controller for the noise-reducing headset was implemented in real-time, which combines analogue and adaptive digital controllers, and can thus reject disturbances which has both broad-band and periodic components. Then

  13. Audible sound treatment of the microalgae Picochlorum oklahomensis for enhancing biomass productivity.

    Science.gov (United States)

    Cai, Weiming; Dunford, Nurhan Turgut; Wang, Ning; Zhu, Songming; He, Huinong

    2016-02-01

    It has been reported in the literature that exposure of microalgae cells to audible sound could promote growth. This study examined the effect of sound waves with the frequency of 1100 Hz, 2200 Hz, and 3300 Hz to stimulate the biomass productivity of an Oklahoma native strain, Picochlorum oklahomensis (PO). The effect of the frequency of sound on biomass mass was measured. This study demonstrated that audible sound treatment of the algae cultures at 2200 Hz was the most effective in terms of biomass production and volumetric oil yield. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. A first course in vibrations and waves

    CERN Document Server

    Samiullah, Mohammad

    2015-01-01

    This book builds on introductory physics and emphasizes understanding of vibratory motion and waves based on first principles. The book is divided into three parts. Part I contains a preliminary chapter that serves as a review of relevant ideas of mechanics and complex numbers. Part II is devoted to a detailed discussion of vibrations of mechanical systems. This part covers a simple harmonic oscillator, coupled oscillators, normal coordinates, beaded string, continuous string, standing waves, and Fourier series. Part II ends with a presentation of stationary solutions of driven finite systems. Part III is concerned with waves. Here, the emphasis is on the discussion of common aspects of all types of waves. The applications to sound, electromagnetic, and matter waves are illustrated. The book also includes examples from water waves and electromagnetic waves on a transmission line. The emphasis of the book is to bring out the similarities among various types of waves. The book includes treatment of reflection a...

  15. Seismic sounding of convection in the Sun

    Science.gov (United States)

    Sreenivasan, Katepalli R.

    2015-11-01

    Thermal convection is the dominant mechanism of energy transport in the outer envelope of the Sun (one-third by radius). It drives global fluid circulations and magnetic fields observed on the solar surface. Convection excites a broadband spectrum of acoustic waves that propagate within the interior and set up modal resonances. These acoustic waves, also called seismic waves, are observed at the surface of the Sun by space- and ground-based telescopes. Seismic sounding, the study of these seismic waves to infer the internal properties of the Sun, constitutes helioseismology. Here we review our knowledge of solar convection, especially that obtained through seismic inference. Several characteristics of solar convection, such as differential rotation, anisotropic Reynolds stresses, the influence of rotation on convection and supergranulation, are considered. On larger scales, several inferences suggest that convective velocities are substantially smaller than those predicted by theory and simulations. This discrepancy challenges the models of internal differential rotation that rely on convective stresses as a driving mechanism and provide an important benchmark for numerical simulations. In collaboration with Shravan Hanasoge, Tata Institute of Fundamental Research, Mumbai and Laurent Gizon, Max-Planck-Institut fuer Sonnensystemforschung, Goettingen.

  16. Three-dimensional reconstruction of sound fields based on the acousto-optic effect

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Torras Rosell, Antoni

    2013-01-01

    The acousto-optic effect can be used to measure the pressure fluctuations in air created by acoustic disturbances (the propagation of light is affected by changes in the medium due to the presence of sound waves). This makes it possible to measure an arbitrary sound field using acousto...... of sound pressure fields from acousto-optic measurements in the audible frequency range, based on Fourier transforms and elementary wave expansion methods. The present study examines the complete reconstruction of the sound field from acousto-optic measurements, recovering all acoustic quantities......-optic tomography via scanning the field with a laser Doppler vibrometer. Consequently, the spatial characteristics of the sound field are captured in the measurement, implicitly bearing the potential for a full holographic reconstruction in a three-dimensional space. Recent studies have examined the reconstruction...

  17. A novel method for direct localized sound speed measurement using the virtual source paradigm

    DEFF Research Database (Denmark)

    Byram, Brett; Trahey, Gregg E.; Jensen, Jørgen Arendt

    2007-01-01

    spatial locations. The method utilizes the sound speed estimator developed by Anderson and Trahey. Their least-squares fit of the received waveform's curvature provides the wave's point of origin. The point of origin and the delay profile calculated from the fit are used to arrive at a spatially...... registered virtual detector. Between a pair of registered virtual detectors a spherical wave is propagated. By beamforming the received data the time of flight between the two virtual sources can be calculated. From this information the local sound speed can be estimated. Validation of the estimator used......Accurate sound speed estimates are desirable in a number of fields, particularly adaptive imaging, and tissue and phantom characterization. In an effort to increase the spatial resolution of sound speed estimates, a new method is proposed for direct measurement of sound speed between arbitrary...

  18. Detection of Electric Response at Excitation of First Sound in He II

    Science.gov (United States)

    Chagovets, Tymofiy V.

    2017-06-01

    The signal of electric response in superfluid helium was recently observed at the excitation of a second sound standing wave in an acoustic resonator (Rybalko in Low Temp Phys 30:994, 2004). It has been suspected that similar resonance signals may be observed also in a first sound wave; however, earlier experiments showed the absence of any electric response induced by the pressure wave. Here, we report the first experimental evidence of electrical activity that arises at the fundamental frequency of the first sound resonance. It is found that the signal of electric response agrees fairly well with the fundamental frequency of the first sound resonance. The absence of the signal of interest in the original experiment is discussed.

  19. Sound synchronization of bubble trains in a viscous fluid: experiment and modeling.

    Science.gov (United States)

    Pereira, Felipe Augusto Cardoso; Baptista, Murilo da Silva; Sartorelli, José Carlos

    2014-10-01

    We investigate the dynamics of formation of air bubbles expelled from a nozzle immersed in a viscous fluid under the influence of sound waves. We have obtained bifurcation diagrams by measuring the time between successive bubbles, having the air flow (Q) as a parameter control for many values of the sound wave amplitude (A), the height (H) of the solution above the top of the nozzle, and three values of the sound frequency (fs). Our parameter spaces (Q,A) revealed a scenario for the onset of synchronization dominated by Arnold tongues (frequency locking) which gives place to chaotic phase synchronization for sufficiently large A. The experimental results were accurately reproduced by numerical simulations of a model combining a simple bubble growth model for the bubble train and a coupling term with the sound wave added to the equilibrium pressure.

  20. Metadevices for the confinement of sound and broadband double-negativity behavior

    DEFF Research Database (Denmark)

    Christensen, Johan; Liang, Z.; Willatzen, Morten

    2013-01-01

    . We extend our theoretical model to analyze structured metal-fluid-metal wave guides for the confinement of sound and present exact expressions for the dispersion relations which describe the hybridization of resonances. We discuss the validity of our analytical model by direct comparison to full-wave...

  1. A Survey on the Feasibility of Sound Classification on Wireless Sensor Nodes

    NARCIS (Netherlands)

    Salomons, E.I. (Etto); Havinga, J.M. (Paul)

    2015-01-01

    Wireless sensor networks are suitable to gain context awareness for indoorenvironments. As sound waves form a rich source of context information, equipping thenodes with microphones can be of great benefit. The algorithms to extract features fromsound waves are often highly computationally

  2. Image Reconstruction in Magnetoacoustic Tomography With Magnetic Induction With Variable Sound Speeds.

    Science.gov (United States)

    Zhang, Wei; Ma, Ren; Zhang, Shunqi; Yin, Tao; Liu, Zhipeng

    2016-12-01

    Acoustic and electrical characteristics of biological tissue are important factors in magnetoacoustic tomography with magnetic induction (MAT-MI). Acoustic inhomogeneity significantly affects the propagations of sound waves. Differences in sound speed lead to distortions of the sound sources in the reconstruction process. The objective of this study is to develop a novel algorithm to reconstruct the sound source distribution in an acoustically inhomogeneous medium. The proposed algorithm is developed on the basis of the finite-difference time-domain method and time-reversal acoustic theory; it combines the relationship among symmetrical transducers with the back-projection algorithm. An acoustically inhomogeneous model with different regions of variable sound speeds is established to validate the proposed algorithm. From the data collected by a rotated focused transducer, first, the sound speed distribution is reconstructed, and then, the sound sources of the model are reconstructed. The reconstructed sound sources are obviously distorted when the speed differences are not considered. In contrast, the proposed algorithm yields reconstructed sound sources that are consistent with the model in terms of shape and size. Thus, the proposed algorithm is capable of accurately reconstructing the acoustic sources distribution in an acoustically inhomogeneous medium. This method provides a solution reducing the influence of acoustic inhomogeneity in MAT-MI. The distributions of sound speed can be obtained during the process of reconstructing the sound source. Consequently, the imaging of the acoustic speed and the electrical conductivity of biological tissues can be implemented simultaneously in MAT-MI.

  3. Non-Line of Sight Sound Propagation Outdoors

    Science.gov (United States)

    You, Chulsoo

    The parabolic equation (PE) method is a useful tool for describing outdoor sound propagation over flat, open, locally reacting ground with a realistic sound speed variation with altitude. The polar parabolic equation (POPE) method is presented here which is an extension of the PE to allow for propagation over irregular terrain (hills). A coordinate system which uses distance along the ground surface and height perpendicular to the surface is introduced into the PE. To verify the numerical accuracy of POPE, computational results are compared to the residue series solution for propagation over a curved surface with a homogeneous atmosphere and to results from a conformal mapping method. The results agree to within one dB. For sound propagation over a 30 m high smooth hill, POPE has been used to calculate transmission loss (TL) for constant sound speed profiles and for upward and downward refracting sound speed profiles. POPE calculations are compared to the experimental data from the Terrain Masking Experiment performed in the vicinity of Instrument Hill at White Sands Missile Range, New Mexico. POPE calculations predict a rapidly decreasing sound level along the masked side of the hill. The field far behind the hill becomes almost constant in level or decreases slowly with distance. The calculation predicts that rays shed along the hillside contribute to the sound level behind the hill and shows that the field level along the ground beyond the base of a hill is determined by the superposition of shedding of rays from the creeping wave and a wave along the flat surface. This effect is strongly affected by the hill shape (hillside) and ground impedance of the hill.

  4. Development of Optophone with No Diaphragm and Application to Sound Measurement in Jet Flow

    Directory of Open Access Journals (Sweden)

    Yoshito Sonoda

    2012-01-01

    Full Text Available The optophone with no diaphragm, which can detect sound waves without disturbing flow of air and sound field, is presented as a novel sound measurement technique and the present status of development is reviewed in this paper. The method is principally based on the Fourier optics and the sound signal is obtained by detecting ultrasmall diffraction light generated from phase modulation by sounds. The principle and theory, which have been originally developed as a plasma diagnostic technique to measure electron density fluctuations in the nuclear fusion research, are briefly introduced. Based on the theoretical analysis, property and merits as a wave-optical sound detection are presented, and the fundamental experiments and results obtained so far are reviewed. It is shown that sounds from about 100 Hz to 100 kHz can be simultaneously detected by a visible laser beam, and the method is very useful to sound measurement in aeroacoustics. Finally, present main problems of the optophone for practical uses in sound and/or noise measurements and the image of technology expected in the future are shortly shown.

  5. Interpolated Sounding and Gridded Sounding Value-Added Products

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. P. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Toto, T. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2016-03-01

    Standard Atmospheric Radiation Measurement (ARM) Climate Research Facility sounding files provide atmospheric state data in one dimension of increasing time and height per sonde launch. Many applications require a quick estimate of the atmospheric state at higher time resolution. The INTERPOLATEDSONDE (i.e., Interpolated Sounding) Value-Added Product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, at 1-minute time resolution, on 332 levels, from the surface up to a limit of approximately 40 km. The grid extends that high so the full height of soundings can be captured; however, most soundings terminate at an altitude between 25 and 30 km, above which no data is provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. In addition, INTERPOLATEDSONDE provides relative humidity scaled to microwave radiometer (MWR) observations.

  6. Sound Quality and Striking Position of a Conga Drum

    Directory of Open Access Journals (Sweden)

    Dylan Harvey

    2014-12-01

    Full Text Available The relationship between the location at which a drum membrane was struck and the quality of sound produced was investigated by striking the drum at several distances between the center and the rim. Through analyzing the harmonics of the wave produced from the impact, it was shown that as the striking location changes, the relative amplitudes of different modes of vibration also changes. It was found that sound of a higher pitch is produced at the rim of the drum than anywhere else on the drum head due to higher modes of vibration becoming dominant.

  7. Spatially extended sound equalisation in rooms at low frequencies

    DEFF Research Database (Denmark)

    Orozco, Arturo

    The thesis describes the results of a theoretical and experimental study of equalisation of the sound field in a room. The theoretical study is based on computer simulations, carried out both in the frequency domain and in the time domain with account taken of the causality of the control filters....... The influence of the number of sources and their position, the number of error sensors and their positions, the frequency range etc. is examined. Among the conclusions can be mentioned that the size of the equalised area can be maximised and the number of loudspeakers can be minimised if the sound field...... that is generated is a propagating plane wave....

  8. Extraordinary absorption of sound in porous lamella-crystals

    DEFF Research Database (Denmark)

    Christensen, Johan; Romero-García, V.; Picó, R.

    2014-01-01

    . Experimental measurements show that strong all-angle sound absorption with almost zero reflectance takes place for a frequency range exceeding two octaves. We demonstrate that lowering the crystal filling fraction increases the wave interaction time and is responsible for the enhancement of intrinsic material......We present the design of a structured material supporting complete absorption of sound with a broadband response and functional for any direction of incident radiation. The structure which is fabricated out of porous lamellas is arranged into a low-density crystal and backed by a reflecting support...

  9. Sound Quality and Striking Position of a Conga Drum

    Directory of Open Access Journals (Sweden)

    Dylan Harvey

    2014-01-01

    Full Text Available The relationship between the location at which a drum membrane was struck and the quality of sound produced was investigated by striking the drum at several distances between the center and the rim. Through analyzing the harmonics of the wave produced from the impact, it was shown that as the striking location changes, the relative amplitudes of different modes of vibration also changes. It was found that sound of a higher pitch is produced at the rim of the drum than anywhere else on the drum head due to higher modes of vibration becoming dominant.

  10. Sound propagation in a turbulent atmosphere near the ground: a parabolic equation approach.

    Science.gov (United States)

    Ostashev, V E; Salomons, E M; Clifford, S F; Lataitis, R J; Wilson, D K; Blanc-Benon, P; Juvé, D

    2001-05-01

    The interference of the direct wave from the point source to the receiver and the wave reflected from the impedance ground in a turbulent atmosphere is studied. A parabolic equation approach for calculating the sound pressure p at the receiver is formulated. Then, the parabolic equation is solved by the Rytov method yielding expressions for the complex phases of direct and ground-reflected waves. Using these expressions, a formula for the mean squared sound pressure [absolute value(p)2] is derived for the case of anisotropic spectra of temperature and wind velocity fluctuations. This formula contains the "coherence factor," which characterizes the coherence between direct and ground-reflected waves. It is shown that the coherence factor is equal to the normalized coherence function of a spherical sound wave for line-of-sight propagation. For the case of isotropic turbulence, this result allows one to obtain analytical formulas for [absolute value(p)2] for the Kolmogorov, Gaussian, and von Karman spectra of temperature and wind velocity fluctuations. Using these formulas, the effects of temperature and wind velocity fluctuations, and the effects of different spectra of these fluctuations on the mean squared sound pressure, are numerically studied. Also the effect of turbulent anisotropy on the interference of direct and ground reflected waves is numerically studied. Finally, it is shown that the mean squared sound pressure [absolute value(p)2] calculated for the von Karman spectrum of temperature fluctuations agrees well with experimental data obtained in a laboratory experiment.

  11. Dispersion of Own Frequency of Ion-Dipole by Supersonic Transverse Wave in Solid

    Directory of Open Access Journals (Sweden)

    Minasyan V.

    2010-10-01

    Full Text Available First, we predict an existence of transverse electromagnetic field formed by supersonic transverse wave in solid. This electromagnetic wave acquires frequency and speed of sound, and it propagates along of direction propagation of supersonic wave. We also show that own frequency of ion-dipole depends on frequency of supersonic transverse wave.

  12. Sound of proteins

    DEFF Research Database (Denmark)

    2007-01-01

    In my group we work with Molecular Dynamics to model several different proteins and protein systems. We submit our modelled molecules to changes in temperature, changes in solvent composition and even external pulling forces. To analyze our simulation results we have so far used visual inspection...... and statistical analysis of the resulting molecular trajectories (as everybody else!). However, recently I started assigning a particular sound frequency to each amino acid in the protein, and by setting the amplitude of each frequency according to the movement amplitude we can "hear" whenever two aminoacids...

  13. Facing Sound - Voicing Art

    DEFF Research Database (Denmark)

    Lønstrup, Ansa

    2013-01-01

    This article is based on examples of contemporary audiovisual art, with a special focus on the Tony Oursler exhibition Face to Face at Aarhus Art Museum ARoS in Denmark in March-July 2012. My investigation involves a combination of qualitative interviews with visitors, observations of the audience......´s interactions with the exhibition and the artwork in the museum space and short analyses of individual works of art based on reception aesthetics and phenomenology and inspired by newer writings on sound, voice and listening....

  14. Handbook for sound engineers

    CERN Document Server

    Ballou, Glen

    2015-01-01

    Handbook for Sound Engineers is the most comprehensive reference available for audio engineers, and is a must read for all who work in audio.With contributions from many of the top professionals in the field, including Glen Ballou on interpretation systems, intercoms, assistive listening, and fundamentals and units of measurement, David Miles Huber on MIDI, Bill Whitlock on audio transformers and preamplifiers, Steve Dove on consoles, DAWs, and computers, Pat Brown on fundamentals, gain structures, and test and measurement, Ray Rayburn on virtual systems, digital interfacing, and preamplifiers

  15. THE SOUNDING WATERS

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2018-01-01

    Church as harmonious moving waters. This vision is shared both by the Eastern and the Western world. With its renewed marble revetments, Aquasgrani still conveys the appearance of the Ambrosian vision of the primordial waters. The church is constructed according to propria dispositione, this is...... and non-sounding phenomena (the figures of choreography). Finally, the paper unveils a dramatization of two choreographies (one physical, another incorporeal, of the soul) unfolding in the space of Aachen which becomes the stage for a Gesamtkunstwerk performance where music and words, and each stone joins...

  16. JINGLE: THE SOUNDING SYMBOL

    Directory of Open Access Journals (Sweden)

    Bysko Maxim V.

    2013-12-01

    Full Text Available The article considers the role of jingles in the industrial era, from the occurrence of the regular radio broadcasting, sound films and television up of modern video games, audio and video podcasts, online broadcasts, and mobile communications. Jingles are researched from the point of view of the theory of symbols: the forward motion is detected in the process of development of jingles from the social symbols (radio callsigns to the individual signs-images (ringtones. The role of technical progress in the formation of jingles as important cultural audio elements of modern digital civilization.

  17. Neuroplasticity beyond sounds

    DEFF Research Database (Denmark)

    Reybrouck, Mark; Brattico, Elvira

    2015-01-01

    adaptations in musicians, following long-term exposure to music, are then reviewed by keeping in mind the distinct subprocesses of a musical aesthetic experience. We conclude that these neural adaptations can be conceived of as the immediate and lifelong interactions with multisensorial stimuli (having...... to the immediate demands of the sounding environment. The resulting neural adaptations in musicians closely depend on the duration of the interactions, the starting age, the involvement of attention, the amount of motor practice and the musical genre played....

  18. Combined multibeam and bathymetry data from Rhode Island Sound and Block Island Sound: a regional perspective

    Science.gov (United States)

    Poppe, Lawrence J.; McMullen, Katherine Y.; Danforth, William W.; Blankenship, Mark R.; Clos, Andrew R.; Glomb, Kimberly A.; Lewit, Peter G.; Nadeau, Megan A.; Wood, Douglas A.; Parker, Castleton E.

    2014-01-01

    Detailed bathymetric maps of the sea floor in Rhode Island and Block Island Sounds are of great interest to the New York, Rhode Island, and Massachusetts research and management communities because of this area's ecological, recreational, and commercial importance. Geologically interpreted digital terrain models from individual surveys provide important benthic environmental information, yet many applications of this information require a geographically broader perspective. For example, individual surveys are of limited use for the planning and construction of cross-sound infrastructure, such as cables and pipelines, or for the testing of regional circulation models. To address this need, we integrated 14 contiguous multibeam bathymetric datasets that were produced by the National Oceanic and Atmospheric Administration during charting operations into one digital terrain model that covers much of Block Island Sound and extends eastward across Rhode Island Sound. The new dataset, which covers over 1244 square kilometers, is adjusted to mean lower low water, gridded to 4-meter resolution, and provided in Universal Transverse Mercator Zone 19, North American Datum of 1983 and geographic World Geodetic Survey of 1984 projections. This resolution is adequate for sea-floor feature and process interpretation but is small enough to be queried and manipulated with standard Geographic Information System programs and to allow for future growth. Natural features visible in the data include boulder lag deposits of winnowed Pleistocene strata, sand-wave fields, and scour depressions that reflect the strength of oscillating tidal currents and scour by storm-induced waves. Bedform asymmetry allows interpretations of net sediment transport. Anthropogenic features visible in the data include shipwrecks and dredged channels. Together the merged data reveal a larger, more continuous perspective of bathymetric topography than previously available, providing a fundamental framework for

  19. Looming sounds are perceived as faster than receding sounds.

    Science.gov (United States)

    Neuhoff, John G

    2016-01-01

    Each year thousands of people are killed by looming motor vehicles. Throughout our evolutionary history looming objects have posed a threat to survival and perceptual systems have evolved unique solutions to confront these environmental challenges. Vision provides an accurate representation of time-to-contact with a looming object and usually allows us to interact successfully with the object if required. However, audition functions as a warning system and yields an anticipatory representation of arrival time, indicating that the object has arrived when it is still some distance away. The bias provides a temporal margin of safety that allows more time to initiate defensive actions. In two studies this bias was shown to influence the perception of the speed of looming and receding sound sources. Listeners heard looming and receding sound sources and judged how fast they were moving. Listeners perceived the speed of looming sounds as faster than that of equivalent receding sounds. Listeners also showed better discrimination of the speed of looming sounds than receding sounds. Finally, close sounds were perceived as faster than distant sounds. The results suggest a prioritization of the perception of the speed of looming and receding sounds that mirrors the level of threat posed by moving objects in the environment.

  20. Age differences in the neuroelectric adaptation to meaningful sounds.

    Directory of Open Access Journals (Sweden)

    Ada W S Leung

    Full Text Available Much of what we know regarding the effect of stimulus repetition on neuroelectric adaptation comes from studies using artificially produced pure tones or harmonic complex sounds. Little is known about the neural processes associated with the representation of everyday sounds and how these may be affected by aging. In this study, we used real life, meaningful sounds presented at various azimuth positions and found that auditory evoked responses peaking at about 100 and 180 ms after sound onset decreased in amplitude with stimulus repetition. This neural adaptation was greater in young than in older adults and was more pronounced when the same sound was repeated at the same location. Moreover, the P2 waves showed differential patterns of domain-specific adaptation when location and identity was repeated among young adults. Background noise decreased ERP amplitudes and modulated the magnitude of repetition effects on both the N1 and P2 amplitude, and the effects were comparable in young and older adults. These findings reveal an age-related difference in the neural processes associated with adaptation to meaningful sounds, which may relate to older adults' difficulty in ignoring task-irrelevant stimuli.

  1. Walrus Movements in Smith Sound

    DEFF Research Database (Denmark)

    Heide-Jørgensen, Mads Peter; Flora, Janne; Andersen, Astrid Oberborbeck

    2017-01-01

    Fifty of 58 walruses (Odobenus rosmarus rosmarus) instrumented with satellite-linked transmitters in four areas in eastern Smith Sound, Northwest Greenland, during May and June of 2010 – 13 and 2015 provided data for this study. These animals departed from the feeding banks along the Greenland...... coast in June – July (average 14th June), simultaneously with the disappearance of sea ice from these areas. Most of them moved to Canadian waters in western Smith Sound. The most frequently used summering grounds were along the coasts of Ellesmere Island: on the eastern coast, the area around Alexandra...... of Jones Sound and Lancaster Sound for short periods during the summer, though this cannot be confirmed with certainty. The return migration from western Smith Sound to the wintering area in eastern Smith Sound takes place in October. The tracked walrus showed high affinity to coastal areas, while walruses...

  2. Applications of Sound Spectrum Analysis

    Science.gov (United States)

    Moran, Timothy

    2007-02-01

    The physics of sound is often studied in introductory physics class experiments involving a tube of resonating air. In typical setups, pistons control the length of a cylindrical space or a microphone is moved within a tube. While these activities are useful and can be made very quantitative, they don't directly demonstrate the sounds that are most familiar to students, such as human voices and musical instruments. Fortunately, several sound spectrum analysis programs are available that can bridge this gap.2

  3. Sound simulaton of granular materials

    OpenAIRE

    Marko, Matej

    2013-01-01

    Title: Sound simulation of granular materials Author: Matej Marko Department: Department of Software and Computer Science Education Supervisor: doc. Ing. Jaroslav Křivánek Ph.D., Department of Software and Computer Science Education Abstract: In recent years, methods for simulating sounds of solid objects, fluids, fire and cloth have been developed. These methods extend existing methods for simulation of the visual behaviour of the respective phenomena and add physically based sounds that cor...

  4. Sounds like Team Spirit

    Science.gov (United States)

    Hoffman, Edward

    2002-01-01

    I recently accompanied my son Dan to one of his guitar lessons. As I sat in a separate room, I focused on the music he was playing and the beautiful, robust sound that comes from a well-played guitar. Later that night, I woke up around 3 am. I tend to have my best thoughts at this hour. The trouble is I usually roll over and fall back asleep. This time I was still awake an hour later, so I got up and jotted some notes down in my study. I was thinking about the pure, honest sound of a well-played instrument. From there my mind wandered into the realm of high-performance teams and successful projects. (I know this sounds weird, but this is the sort of thing I think about at 3 am. Maybe you have your own weird thoughts around that time.) Consider a team in relation to music. It seems to me that a crack team can achieve a beautiful, perfect unity in the same way that a band of brilliant musicians can when they're in harmony with one another. With more than a little satisfaction I have to admit, I started to think about the great work performed for you by the Knowledge Sharing team, including this magazine you are reading. Over the past two years I personally have received some of my greatest pleasures as the APPL Director from the Knowledge Sharing activities - the Masters Forums, NASA Center visits, ASK Magazine. The Knowledge Sharing team expresses such passion for their work, just like great musicians convey their passion in the music they play. In the case of Knowledge Sharing, there are many factors that have made this so enjoyable (and hopefully worthwhile for NASA). Three ingredients come to mind -- ingredients that have produced a signature sound. First, through the crazy, passionate playing of Alex Laufer, Michelle Collins, Denise Lee, and Todd Post, I always know that something startling and original is going to come out of their activities. This team has consistently done things that are unique and innovative. For me, best of all is that they are always

  5. Analysis of environmental sounds

    Science.gov (United States)

    Lee, Keansub

    Environmental sound archives - casual recordings of people's daily life - are easily collected by MPS players or camcorders with low cost and high reliability, and shared in the web-sites. There are two kinds of user generated recordings we would like to be able to handle in this thesis: Continuous long-duration personal audio and Soundtracks of short consumer video clips. These environmental recordings contain a lot of useful information (semantic concepts) related with activity, location, occasion and content. As a consequence, the environment archives present many new opportunities for the automatic extraction of information that can be used in intelligent browsing systems. This thesis proposes systems for detecting these interesting concepts on a collection of these real-world recordings. The first system is to segment and label personal audio archives - continuous recordings of an individual's everyday experiences - into 'episodes' (relatively consistent acoustic situations lasting a few minutes or more) using the Bayesian Information Criterion and spectral clustering. The second system is for identifying regions of speech or music in the kinds of energetic and highly-variable noise present in this real-world sound. Motivated by psychoacoustic evidence that pitch is crucial in the perception and organization of sound, we develop a noise-robust pitch detection algorithm to locate speech or music-like regions. To avoid false alarms resulting from background noise with strong periodic components (such as air-conditioning), a new scheme is added in order to suppress these noises in the domain of autocorrelogram. In addition, the third system is to automatically detect a large set of interesting semantic concepts; which we chose for being both informative and useful to users, as well as being technically feasible. These 25 concepts are associated with people's activities, locations, occasions, objects, scenes and sounds, and are based on a large collection of

  6. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  7. Sound [signal] noise

    DEFF Research Database (Denmark)

    Bjørnsten, Thomas

    2012-01-01

    The article discusses the intricate relationship between sound and signification through notions of noise. The emergence of new fields of sonic artistic practices has generated several questions of how to approach sound as aesthetic form and material. During the past decade an increased attention...... has been paid to, for instance, a category such as ‘sound art’ together with an equally strengthened interest in phenomena and concepts that fall outside the accepted aesthetic procedures and constructions of what we traditionally would term as musical sound – a recurring example being ‘noise’....

  8. Transport waves as crystal excitations

    Science.gov (United States)

    Cepellotti, Andrea; Marzari, Nicola

    2017-09-01

    We introduce the concept of transport waves by showing that the linearized Boltzmann transport equation admits excitations in the form of waves that have well-defined dispersion relations and decay times. Crucially, these waves do not represent single-particle excitations, but are collective excitations of the equilibrium distribution functions. We study in detail the case of thermal transport, where relaxons are found in the long-wavelength limit, and second sound is reinterpreted as the excitation of one or several temperature waves at finite frequencies. Graphene is studied numerically, finding decay times of the order of microseconds. The derivation, obtained by a spectral representation of the Boltzmann equation, holds in principle for any crystal or semiclassical transport theory and is particularly relevant when transport takes place in the hydrodynamic regime.

  9. Interpolated Sounding and Gridded Sounding Value-Added Products

    Energy Technology Data Exchange (ETDEWEB)

    Toto, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Jensen, M. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-01

    Standard Atmospheric Radiation Measurement (ARM) Climate Research Facility sounding files provide atmospheric state data in one dimension of increasing time and height per sonde launch. Many applications require a quick estimate of the atmospheric state at higher time resolution. The INTERPOLATEDSONDE (i.e., Interpolated Sounding) Value-Added Product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, at 1-minute time resolution, on 332 levels, from the surface up to a limit of approximately 40 km. The grid extends that high so the full height of soundings can be captured; however, most soundings terminate at an altitude between 25 and 30 km, above which no data is provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. In addition, INTERPOLATEDSONDE provides relative humidity scaled to microwave radiometer (MWR) observations.The INTERPOLATEDSONDE VAP, a continuous time-height grid of relative humidity-corrected sounding data, is intended to provide input to higher-order products, such as the Merged Soundings (MERGESONDE; Troyan 2012) VAP, which extends INTERPOLATEDSONDE by incorporating model data. The INTERPOLATEDSONDE VAP also is used to correct gaseous attenuation of radar reflectivity in products such as the KAZRCOR VAP.

  10. A Study of Sound Contents Development based On Analysis and Compare Foley Sound to Actual Sound of Wind

    OpenAIRE

    Ik-Soo Ahn; Seong-Geon Bae; Myung-Jin Bae

    2015-01-01

    Foley sound of wind is often used as a background sound of radio drama in early period of broadcasting. It is one of the tools that has applied the most creative and scientific theory. This research provides scientific proof on similarities and creativity of Foley sound of wind through comparison and analysis of Foley sound and the actual wind sound.

  11. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  12. Growth and physiological characteristics of E. coli in response to the exposure of sound field.

    Science.gov (United States)

    Gu, Shao-Bin; Yang, Bin; Wu, Ying; Li, Shi-Chang; Liu, Wen; Duan, Xiao-Fei; Li, Meng-Wei

    2013-09-15

    It is undeniable that environmental sonic vibration can affect our emotions and mood, but so far the study of physical stimuli provoked by audible wave on single cells has been rarely concerned. To investigate the response of E. coli to audible wave exposure, the growth status and alterations in antioxidant enzyme activity were studied in liquid culture. The data showed that the growth of E. coli was promoted in the treatments of different frequencies sound wave. The most significant effect on growth promotion appeared when sound wave was maintained at 100 dB and 5000 Hz. Simultaneously, sonic vibration evoked significantly increases the level of total protein content contents. And the changes of activities of Super Oxide Dismutase (SOD) and catalase (CAT) were observed obviously. The results suggested that the growth promotion effect of audible sound may be non-linear and shows obvious frequency and intensity peculiarities. Moreover, the increase in activity of antioxidant enzymes implied that a number of active oxygen species generated in bacterial cell under the exposure of audible sound. We speculate that the audible sound may cause a secondary oxidative stress. Further studies are needed to elucidate the mechanisms of active oxygen species generation induced by audible sound.

  13. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  14. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  15. Spontaneous waves in muscle fibres

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Stefan; Kruse, Karsten [Department of Theoretical Physics, Saarland University, 66041 Saarbruecken (Germany); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, 01187 Dresden (Germany)

    2007-11-15

    Mechanical oscillations are important for many cellular processes, e.g. the beating of cilia and flagella or the sensation of sound by hair cells. These dynamic states originate from spontaneous oscillations of molecular motors. A particularly clear example of such oscillations has been observed in muscle fibers under non-physiological conditions. In that case, motor oscillations lead to contraction waves along the fiber. By a macroscopic analysis of muscle fiber dynamics we find that the spontaneous waves involve non-hydrodynamic modes. A simple microscopic model of sarcomere dynamics highlights mechanical aspects of the motor dynamics and fits with the experimental observations.

  16. Modelling of sound fields through austenitic welds

    Science.gov (United States)

    Schmitz, V.; Kröning, M.; Chakhlov, S.

    2000-05-01

    The propagation paths of ultrasonic waves through austenitic weld material can not be predicted due to the anisotropic and inhomogeneous structure of the weld. To support an NDT-inspector Ogilvy's ray tracing algorithm has been implemented to follow virtually in three dimensions longitudinal, horizontal and vertical polarized shear wave propagation from the basic material through the cladding. The algorithm has been implemented in a software package "3D-CAD-Ray" which allows to model the experiment in a 3D-CAD drawing and to visualize the rays including reflections from lack of side wall fusions or inner surface connected cracks. The defects can be placed, sized or oriented arbitrarily which allows to perform a parametric study. Results of the algorithm are presented and checked against the experiment. The measured elastic constants and the orientation of the grains taken from micrographs have been entered properly into the CAD-model. The spreading effect for the sound field perpendicular to the orientation of the weld—observed during the experiments—could be confirmed for the SH-, SV- and longitudinal waves by the theoretical predictions. Animations are shown for fixed probe positions where rays and mode converted rays are shown marching on in time and for scans in pulse echo technique where the probe is moved towards the weld.

  17. Theoretical analysis of sound transmission loss through graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp [Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan); Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Ni, Qing-Qing [Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan)

    2014-11-17

    We examine the potential of using graphene sheets (GSs) as sound insulating materials that can be used for nano-devices because of their small size, super electronic, and mechanical properties. In this study, a theoretical analysis is proposed to predict the sound transmission loss through multi-layered GSs, which are formed by stacks of GS and bound together by van der Waals (vdW) forces between individual layers. The result shows that the resonant frequencies of the sound transmission loss occur in the multi-layered GSs and the values are very high. Based on the present analytical solution, we predict the acoustic insulation property for various layers of sheets under both normal incident wave and acoustic field of random incidence source. The scheme could be useful in vibration absorption application of nano devices and materials.

  18. Microscopic theory of longitudinal sound velocity in charge ordered manganites.

    Science.gov (United States)

    Rout, G C; Panda, S

    2009-10-14

    A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e(g) band, an exchange interaction between spins of the itinerant e(g) band electrons and the core t(2g) electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

  19. Sound attenuation and anharmonic damping in solids with correlated disorder

    Directory of Open Access Journals (Sweden)

    W. Schirmacher

    2010-01-01

    Full Text Available We study via self-consistent Born approximation a model for sound waves in a disordered environment, in which the local fluctuations of the shear modulus G are spatially correlated with a certain correlation length ξ. The theory predicts an enhancement of the density of states over Debye's ω2 law (boson peak whose intensity increases for increasing correlation length, and whose frequency position is shifted downwards as 1/ξ. Moreover, the predicted disorder-induced sound attenuation coefficient Γ(k obeys a universal scaling law ξ Γ(k = f(kξ for a given variance of G. Finally, the inclusion of the lowest-order contribution to the anharmonic sound damping into the theory allows us to reconcile apparently contradictory recent experimental data in amorphous SiO2.

  20. Metasurface for Water-to-Air Sound Transmission

    Science.gov (United States)

    Bok, Eun; Park, Jong Jin; Choi, Haejin; Han, Chung Kyu; Wright, Oliver B.; Lee, Sam H.

    2018-01-01

    Effective transmission of sound from water to air is crucial for the enhancement of the detection sensitivity of underwater sound. However, only 0.1% of the acoustic energy is naturally transmitted at such a boundary. At audio frequencies, quarter-wave plates or multilayered antireflection coatings are too bulky for practical use for such enhancement. Here we present an acoustic metasurface of a thickness of only ˜λ /100 , where λ is the wavelength in air, consisting of an array of meta-atoms that each contain a set of membranes and an air-filled cavity. We experimentally demonstrate that such a meta-atom increases the transmission of sound at ˜700 Hz by 2 orders of magnitude, allowing about 30% of the incident acoustic power from water to be transmitted into air. Applications include underwater sonic sensing and communication.