An aircraft noise pollution model for trajectory optimization

Science.gov (United States)

Barkana, A.; Cook, G.

1976-01-01

A mathematical model describing the generation of aircraft noise is developed with the ultimate purpose of reducing noise (noise-optimizing landing trajectories) in terminal areas. While the model is for a specific aircraft (Boeing 737), the methodology would be applicable to a wide variety of aircraft. The model is used to obtain a footprint on the ground inside of which the noise level is at or above 70 dB.

Aircraft Noise Reduction Subproject Overview

Science.gov (United States)

Fernandez, Hamilton; Nark, Douglas M.; Van Zante, Dale E.

2016-01-01

The material presents highlights of propulsion and airframe noise research being completed for the Advanced Air Transport Technology Project. The basis of noise reduction plans along with representative work for the airframe, propulsion, and propulsion-airframe integration is discussed for the Aircraft Noise reduction Subproject.

The community response to aircraft noise around six Spanish airports

Science.gov (United States)

Garcia, A.; Faus, L. J.; Garcia, A. M.

1993-06-01

The community response to aircraft noise has been studied through a social survey. A total of 1800 persons living in the vicinity of six major Spanish airports have been interviewed at their homes concerning the environmental quality of the area, dissatisfaction with road traffic noise and aircraft noise, activities interfered with by noise, most disturbing aircraft types, and subjective evaluation of airport impact. All the responses obtained in this survey have been compared with aircraft noise levels corresponding to the residence locations of the people interviewed (values of NEF levels were calculated with the INM model). The results obtained in this work allow one to evaluate the impact of aircraft noise under a wide range of different situations.

Effects of Aircraft Noise and Sonic Booms on Domestic Animals and Wildlife: Bibliographic Abstracts

Science.gov (United States)

1988-06-01

However, noise-exposed mice experienceda longer time interval between litters and lower weight gain of young, compared to the controls. Busnel, R.G., and...effects of sounds of varying intensities. Poult. Sci. 37:776-779. Broiler chickens were exposed to recorded airfield noise and aircraft flyovers from the...pen of broilers is more likely to occur from an isolated low-level flyover than from continuous noise resulting from close proximity to an airfield

Potential for Landing Gear Noise Reduction on Advanced Aircraft Configurations

Science.gov (United States)

Thomas, Russell H.; Nickol, Craig L.; Burley, Casey L.; Guo, Yueping

2016-01-01

The potential of significantly reducing aircraft landing gear noise is explored for aircraft configurations with engines installed above the wings or the fuselage. An innovative concept is studied that does not alter the main gear assembly itself but does shorten the main strut and integrates the gear in pods whose interior surfaces are treated with acoustic liner. The concept is meant to achieve maximum noise reduction so that main landing gears can be eliminated as a major source of airframe noise. By applying this concept to an aircraft configuration with 2025 entry-into-service technology levels, it is shown that compared to noise levels of current technology, the main gear noise can be reduced by 10 EPNL dB, bringing the main gear noise close to a floor established by other components such as the nose gear. The assessment of the noise reduction potential accounts for design features for the advanced aircraft configuration and includes the effects of local flow velocity in and around the pods, gear noise reflection from the airframe, and reflection and attenuation from acoustic liner treatment on pod surfaces and doors. A technical roadmap for maturing this concept is discussed, and the possible drag increase at cruise due to the addition of the pods is identified as a challenge, which needs to be quantified and minimized possibly with the combination of detailed design and application of drag reduction technologies.

Aircraft noise, health, and residential sorting: evidence from two quasi-experiments.

Science.gov (United States)

Boes, Stefan; Nüesch, Stephan; Stillman, Steven

2013-09-01

We explore two unexpected changes in flight regulations to estimate the causal effect of aircraft noise on health. Detailed measures of noise are linked with longitudinal data on individual health outcomes based on the exact address information. Controlling for individual heterogeneity and spatial sorting into different neighborhoods, we find that aircraft noise significantly increases sleeping problems and headaches. Models that do not control for such heterogeneity and sorting substantially underestimate the negative health effects, which suggests that individuals self-select into residence based on their unobserved sensitivity to noise. Our study demonstrates that the combination of quasi-experimental variation and panel data is very powerful for identifying causal effects in epidemiological field studies. Copyright © 2013 John Wiley & Sons, Ltd.

An Overview of Virtual Acoustic Simulation of Aircraft Flyover Noise

Science.gov (United States)

Rizzi, Stephen A.

2013-01-01

Methods for testing human subject response to aircraft flyover noise have greatly advanced in recent years as a result of advances in simulation technology. Capabilities have been developed which now allow subjects to be immersed both visually and aurally in a three-dimensional, virtual environment. While suitable for displaying recorded aircraft noise, the true potential is found when synthesizing aircraft flyover noise because it allows the flexibility and freedom to study sounds from aircraft not yet flown. A virtual acoustic simulation method is described which is built upon prediction-based source noise synthesis, engineering-based propagation modeling, and empirically-based receiver modeling. This source-path-receiver paradigm allows complete control over all aspects of flyover auralization. With this capability, it is now possible to assess human response to flyover noise by systematically evaluating source noise reductions within the context of a system level simulation. Examples of auralized flyover noise and movie clips representative of an immersive aircraft flyover environment are made in the presentation.

Aircraft noise in the region of the Bucharest-Otopeni Airport. [noise pollution in airport environment

Science.gov (United States)

Costescu, M.; Gherghel, C.; Curtoglu, A.

1974-01-01

Aircraft noise, especially in the region adjoining airports, constitutes a problem that will be aggravated in the near future because of increasing aircraft traffic and the appearance of new types of large tonnage aircraft with continuously increasing powers and speeds. Criteria for the evaluation of aircraft noise are reported and some results of studies carried out in the region of Bucharest-Otopeni Airport are detailed.

Quelling Cabin Noise in Turboprop Aircraft via Active Control

Science.gov (United States)

Kincaid, Rex K.; Laba, Keith E.; Padula, Sharon L.

1997-01-01

Cabin noise in turboprop aircraft causes passenger discomfort, airframe fatigue, and employee scheduling constraints due to OSHA standards for exposure to high levels of noise. The noise levels in the cabins of turboprop aircraft are typically 10 to 30 decibels louder than commercial jet noise levels. However. unlike jet noise the turboprop noise spectrum is dominated by a few low frequency tones. Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The goal is to determine the force inputs and locations for the piezoceramic actuators so that: (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. Computational experiments for data taken from a computer generated model and from a laboratory test article at NASA Langley Research Center are provided.

Annoyance by aircraft noise and fear of overflying aircraft in relation to attitudes toward the environment and community

Science.gov (United States)

Loeb, M.; Moran, S. V.

1977-01-01

It has been suggested that expressions of annoyance attributable to aircraft noise may reflect in part fear of aircraft overflights and possible crashes. If this is true, then residents of areas where crashes have occurred should express more annoyance. To test this hypothesis, 50 residents of an Albany, New York area where an aircraft crash producing fatalities recently occurred and 50 residents of a comparable nearby area without such a history, were asked to respond to a 'Quality of Life Questionnaire.' Among the items were some designed to test annoyance by noise and fear of aircraft overflights. It was predicted that those in the crash area would express more fear and would more often identify aircraft as a noise source. These hypotheses were sustained. A near-replication was carried out in Louisville, Kentucky; results were much the same. Analyses indicated that for the crash-area groups, there was associating of aircraft fear and noise annoyance responses; this was true to an apparently lesser extent for non-crash groups. The greater annoyance of crash groups by aircraft community noise apparently does not carry over to situations in which aircraft noise is assessed in the laboratory.

Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise

Directory of Open Access Journals (Sweden)

Sabine A. Janssen

2011-05-01

Full Text Available In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A‑weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels.

The Low-Noise Potential of Distributed Propulsion on a Catamaran Aircraft

Science.gov (United States)

Posey, Joe W.; Tinetti, A. F.; Dunn, M. H.

2006-01-01

The noise shielding potential of an inboard-wing catamaran aircraft when coupled with distributed propulsion is examined. Here, only low-frequency jet noise from mid-wing-mounted engines is considered. Because low frequencies are the most difficult to shield, these calculations put a lower bound on the potential shielding benefit. In this proof-of-concept study, simple physical models are used to describe the 3-D scattering of jet noise by conceptualized catamaran aircraft. The Fast Scattering Code is used to predict noise levels on and about the aircraft. Shielding results are presented for several catamaran type geometries and simple noise source configurations representative of distributed propulsion radiation. Computational analyses are presented that demonstrate the shielding benefits of distributed propulsion and of increasing the width of the inboard wing. Also, sample calculations using the FSC are presented that demonstrate additional noise reduction on the aircraft fuselage by the use of acoustic liners on the inboard wing trailing edge. A full conceptual aircraft design would have to be analyzed over a complete mission to more accurately quantify community noise levels and aircraft performance, but the present shielding calculations show that a large acoustic benefit could be achieved by combining distributed propulsion and liner technology with a twin-fuselage planform.

Aircraft noise, air pollution, and mortality from myocardial infarction.

Science.gov (United States)

Huss, Anke; Spoerri, Adrian; Egger, Matthias; Röösli, Martin

2010-11-01

Myocardial infarction has been associated with both transportation noise and air pollution. We examined residential exposure to aircraft noise and mortality from myocardial infarction, taking air pollution into account. We analyzed the Swiss National Cohort, which includes geocoded information on residence. Exposure to aircraft noise and air pollution was determined based on geospatial noise and air-pollution (PM10) models and distance to major roads. We used Cox proportional hazard models, with age as the timescale. We compared the risk of death across categories of A-weighted sound pressure levels (dB(A)) and by duration of living in exposed corridors, adjusting for PM10 levels, distance to major roads, sex, education, and socioeconomic position of the municipality. We analyzed 4.6 million persons older than 30 years who were followed from near the end of 2000 through December 2005, including 15,532 deaths from myocardial infarction (ICD-10 codes I 21, I 22). Mortality increased with increasing level and duration of aircraft noise. The adjusted hazard ratio comparing ≥60 dB(A) with noise. Aircraft noise was associated with mortality from myocardial infarction, with a dose-response relationship for level and duration of exposure. The association does not appear to be explained by exposure to particulate matter air pollution, education, or socioeconomic status of the municipality.

Optimised Sound Absorbing Trim Panels for the Reduction of Aircraft Cabin Noise

NARCIS (Netherlands)

Hannink, M.H.C.; Wijnant, Ysbrand H.; de Boer, Andries; Ivanov, N.I.; Crocker, M.J.

2004-01-01

The EU project FACE (Friendly Aircraft Cabin Environment) aims to improve the environmental comfort in aircraft cabins. As part of this project, this paper focuses on the reduction of noise in aircraft cabins. For modern aircraft flying at cruise conditions, this cabin noise is known to be dominated

Trends in aircraft noise annoyance: The role of study and sample characteristics

NARCIS (Netherlands)

Kroesen, M.; Molin, E.J.E.; Miedema, H.M.E.; Vos, H.; Janssen, S.A.; Wee, B. van

2010-01-01

This study assesses the effects of aircraft noise on residential satisfaction, an important indicator of subjective well-being. A structural equation model is specified that estimates the relationships between objective variables, noise annoyance variables and residential satisfaction. Secondary

Landing Gear Noise Prediction and Analysis for Tube-and-Wing and Hybrid-Wing-Body Aircraft

Science.gov (United States)

Guo, Yueping; Burley, Casey L.; Thomas, Russell H.

2016-01-01

Improvements and extensions to landing gear noise prediction methods are developed. New features include installation effects such as reflection from the aircraft, gear truck angle effect, local flow calculation at the landing gear locations, gear size effect, and directivity for various gear designs. These new features have not only significantly improved the accuracy and robustness of the prediction tools, but also have enabled applications to unconventional aircraft designs and installations. Systematic validations of the improved prediction capability are then presented, including parametric validations in functional trends as well as validations in absolute amplitudes, covering a wide variety of landing gear designs, sizes, and testing conditions. The new method is then applied to selected concept aircraft configurations in the portfolio of the NASA Environmentally Responsible Aviation Project envisioned for the timeframe of 2025. The landing gear noise levels are on the order of 2 to 4 dB higher than previously reported predictions due to increased fidelity in accounting for installation effects and gear design details. With the new method, it is now possible to reveal and assess the unique noise characteristics of landing gear systems for each type of aircraft. To address the inevitable uncertainties in predictions of landing gear noise models for future aircraft, an uncertainty analysis is given, using the method of Monte Carlo simulation. The standard deviation of the uncertainty in predicting the absolute level of landing gear noise is quantified and determined to be 1.4 EPNL dB.

Airframe Noise from a Hybrid Wing Body Aircraft Configuration

Science.gov (United States)

Hutcheson, Florence V.; Spalt, Taylor B.; Brooks, Thomas F.; Plassman, Gerald E.

2016-01-01

A high fidelity aeroacoustic test was conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel to establish a detailed database of component noise for a 5.8% scale HWB aircraft configuration. The model has a modular design, which includes a drooped and a stowed wing leading edge, deflectable elevons, twin verticals, and a landing gear system with geometrically scaled wheel-wells. The model is mounted inverted in the test section and noise measurements are acquired at different streamwise stations from an overhead microphone phased array and from overhead and sideline microphones. Noise source distribution maps and component noise spectra are presented for airframe configurations representing two different approach flight conditions. Array measurements performed along the aircraft flyover line show the main landing gear to be the dominant contributor to the total airframe noise, followed by the nose gear, the inboard side-edges of the LE droop, the wing tip/LE droop outboard side-edges, and the side-edges of deployed elevons. Velocity dependence and flyover directivity are presented for the main noise components. Decorrelation effects from turbulence scattering on spectral levels measured with the microphone phased array are discussed. Finally, noise directivity maps obtained from the overhead and sideline microphone measurements for the landing gear system are provided for a broad range of observer locations.

Effects of cavity resonances on sound transmission into a thin cylindrical shell. [noise reduction in aircraft fuselage

Science.gov (United States)

Koval, L. R.

1978-01-01

In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the effects of internal cavity resonances on sound transmission into a thin cylindrical shell. The 'noise reduction' of the cylinder is defined and computed, with and without including the effects of internal cavity resonances. As would be expected, the noise reduction in the absence of cavity resonances follows the same qualitative pattern as does transmission loss. Numerical results show that cavity resonances lead to wide fluctuations and a general decrease of noise reduction, especially at cavity resonances. Modest internal absorption is shown to greatly reduce the effect of cavity resonances. The effects of external airflow, internal cabin pressurization, and different acoustical properties inside and outside the cylinder are also included and briefly examined.

Design and test of aircraft engine isolators for reduced interior noise

Science.gov (United States)

Unruh, J. F.; Scheidt, D. C.

1982-01-01

Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.

On the dominant noise components of tactical aircraft: Laboratory to full scale

Science.gov (United States)

Tam, Christopher K. W.; Aubert, Allan C.; Spyropoulos, John T.; Powers, Russell W.

2018-05-01

This paper investigates the dominant noise components of a full-scale high performance tactical aircraft. The present study uses acoustic measurements of the exhaust jet from a single General Electric F414-400 turbofan engine installed in a Boeing F/A-18E Super Hornet aircraft operating from flight idle to maximum afterburner. The full-scale measurements are to the ANSI S12.75-2012 standard employing about 200 microphones. By comparing measured noise spectra with those from hot supersonic jets observed in the laboratory, the dominant noise components specific to the F/A-18E aircraft at different operating power levels are identified. At intermediate power, it is found that the dominant noise components of an F/A-18E aircraft are essentially the same as those of high temperature supersonic laboratory jets. However, at military and afterburner powers, there are new dominant noise components. Their characteristics are then documented and analyzed. This is followed by an investigation of their origin and noise generation mechanisms.

Aircraft noise, air pollution, and mortality from myocardial infarction.

NARCIS (Netherlands)

Huss, A.; Spoerri, A.; Egger, M.; Roosli, M.

2010-01-01

OBJECTIVE: Myocardial infarction has been associated with both transportation noise and air pollution. We examined residential exposure to aircraft noise and mortality from myocardial infarction, taking air pollution into account. METHODS: We analyzed the Swiss National Cohort, which includes

A Process for Assessing NASA's Capability in Aircraft Noise Prediction Technology

Science.gov (United States)

Dahl, Milo D.

2008-01-01

An acoustic assessment is being conducted by NASA that has been designed to assess the current state of the art in NASA s capability to predict aircraft related noise and to establish baselines for gauging future progress in the field. The process for determining NASA s current capabilities includes quantifying the differences between noise predictions and measurements of noise from experimental tests. The computed noise predictions are being obtained from semi-empirical, analytical, statistical, and numerical codes. In addition, errors and uncertainties are being identified and quantified both in the predictions and in the measured data to further enhance the credibility of the assessment. The content of this paper contains preliminary results, since the assessment project has not been fully completed, based on the contributions of many researchers and shows a select sample of the types of results obtained regarding the prediction of aircraft noise at both the system and component levels. The system level results are for engines and aircraft. The component level results are for fan broadband noise, for jet noise from a variety of nozzles, and for airframe noise from flaps and landing gear parts. There are also sample results for sound attenuation in lined ducts with flow and the behavior of acoustic lining in ducts.

Airport acoustics: Aircraft noise distribution and modelling of some ...

African Journals Online (AJOL)

Airport acoustics: Aircraft noise distribution and modelling of some aircraft parameters. MU Onuu, EO Obisung. Abstract. No Abstract. Nigerian Journal of Physics Vol. 17 (Supplement) 2005: pp. 177-186. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Acoustic guide for noise-transmission testing of aircraft

Science.gov (United States)

Vaicaitis, Rimas (Inventor)

1987-01-01

Selective testing of aircraft or other vehicular components without requiring disassembly of the vehicle or components was accomplished by using a portable guide apparatus. The device consists of a broadband noise source, a guide to direct the acoustic energy, soft sealing insulation to seal the guide to the noise source and to the vehicle component, and noise measurement microphones, both outside the vehicle at the acoustic guide output and inside the vehicle to receive attenuated sound. By directing acoustic energy only to selected components of a vehicle via the acoustic guide, it is possible to test a specific component, such as a door or window, without picking up extraneous noise which may be transmitted to the vehicle interior through other components or structure. This effect is achieved because no acoustic energy strikes the vehicle exterior except at the selected component. Also, since the test component remains attached to the vehicle, component dynamics with vehicle frame are not altered.

Open Rotor Noise Shielding by Blended-Wing-Body Aircraft

Science.gov (United States)

Guo, Yueping; Czech, Michael J.; Thomas, Russell H.

2015-01-01

This paper presents an analysis of open rotor noise shielding by Blended Wing Body (BWB) aircraft by using model scale test data acquired in the Boeing Low Speed Aeroacoustic Facility (LSAF) with a legacy F7/A7 rotor model and a simplified BWB platform. The objective of the analysis is the understanding of the shielding features of the BWB and the method of application of the shielding data for noise studies of BWB aircraft with open rotor propulsion. By studying the directivity patterns of individual tones, it is shown that though the tonal energy distribution and the spectral content of the wind tunnel test model, and thus its total noise, may differ from those of more advanced rotor designs, the individual tones follow directivity patterns that characterize far field radiations of modern open rotors, ensuring the validity of the use of this shielding data. Thus, open rotor tonal noise shielding should be categorized into front rotor tones, aft rotor tones and interaction tones, not only because of the different directivities of the three groups of tones, but also due to the differences in their source locations and coherence features, which make the respective shielding characteristics of the three groups of tones distinctly different from each other. To reveal the parametric trends of the BWB shielding effects, results are presented with variations in frequency, far field emission angle, rotor operational condition, engine installation geometry, and local airframe features. These results prepare the way for the development of parametric models for the shielding effects in prediction tools.

Aircraft Engine Noise Research and Testing at the NASA Glenn Research Center

Science.gov (United States)

Elliott, Dave

2015-01-01

The presentation will begin with a brief introduction to the NASA Glenn Research Center as well as an overview of how aircraft engine noise research fits within the organization. Some of the NASA programs and projects with noise content will be covered along with the associated goals of aircraft noise reduction. Topics covered within the noise research being presented will include noise prediction versus experimental results, along with engine fan, jet, and core noise. Details of the acoustic research conducted at NASA Glenn will include the test facilities available, recent test hardware, and data acquisition and analysis methods. Lastly some of the actual noise reduction methods investigated along with their results will be shown.

An overview of practice and regulations concerning aircraft noise protection in Serbia

Directory of Open Access Journals (Sweden)

Mirković Bojana D.

2015-01-01

Full Text Available This paper gives an overview of studies and regulation concerning the issue of aircraft noise protection in Republic of Serbia. After crossing the limit of 50.000 operations in 2014, Airport 'Nikola Tesla' is classified as major airport, and with that urged to fulfill various requirements related to nose protection. Major airports are obliged to monitor noise, as well as to prepare strategic noise maps and action plans aiming to decrease number of people exposed to aircraft noise above acceptable level.

QCGAT aircraft/engine design for reduced noise and emissions

Science.gov (United States)

Lanson, L.; Terrill, K. M.

1980-01-01

The high bypass ratio QCGAT engine played an important role in shaping the aircraft design. The aircraft which evolved is a sleek, advanced design, six-place aircraft with 3538 kg (7,800 lb) maximum gross weight. It offers a 2778 kilometer (1500 nautical mile) range with cruise speed of 0.5 Mach number and will take-off and land on the vast majority of general aviation airfields. Advanced features include broad application of composite materials and a supercritical wing design with winglets. Full-span fowler flaps were introduced to improve landing capability. Engines are fuselage-mounted with inlets over the wing to provide shielding of fan noise by the wing surfaces. The design objectives, noise, and emission considerations, engine cycle and engine description are discussed as well as specific design features.

Noise Reduction Efforts for Special Operations C-130 Aircraft Using Active Synchrophaser Control

National Research Council Canada - National Science Library

Hammond, Daryl; McKinley, Richard; Hale, Bill

1998-01-01

Aircraft noise often inhibits mission effectiveness. As a result, flight crews, ground maintenance personnel, and passengers suffer degraded voice communication, impaired performance, increased fatigue, and hearing loss...

Structureborne noise measurements on a small twin-engine aircraft

Science.gov (United States)

Cole, J. E., III; Martini, K. F.

1988-01-01

Structureborne noise measurements performed on a twin-engine aircraft (Beechcraft Baron) are reported. There are two overall objectives of the test program. The first is to obtain data to support the development of analytical models of the wing and fuselage, while the second is to evaluate effects of structural parameters on cabin noise. Measurements performed include structural and acoustic responses to impact excitation, structural and acoustic loss factors, and modal parameters of the wing. Path alterations include added mass to simulate fuel, variations in torque of bolts joining wing and fuselage, and increased acoustic absorption. Conclusions drawn regarding these measurements are presented.

Children's cognition and aircraft noise exposure at home--the West London Schools Study.

Science.gov (United States)

Matsui, T; Stansfeld, S; Haines, M; Head, J

2004-01-01

The association of aircraft noise exposure with cognitive performance was examined by means of a cross-sectional field survey. Two hundred thirty six children attending 10 primary schools around Heathrow Airport in west London were tested on reading comprehension, immediate/delayed recall and sustained attention. In order to obtain the information about their background, a questionnaire was delivered to the parents and 163 answers were collected. Logistic regression models were used to assess performance on the cognitive tests in relation to aircraft noise exposure at home and possible individual and school level confounding factors. A significant dose-response relationship was found between aircraft noise exposure at home and performance on memory tests of immediate/delayed recall. However there was no strong association with the other cognitive outcomes. These results suggest that aircraft noise exposure at home may affect children's memory.

An experimental evaluation of a new approach to aircraft noise modelling

NARCIS (Netherlands)

Roo, F. de; Salomons, E.M.

2008-01-01

Common engineering models for aircraft noise, such as INM, yield noise levels by interpolation of Noise Power Distance (NPD) tables. In the European project Imagine (2004 - 2006), a different approach was proposed: the source is characterized by an emission spectrum and the received noise spectrum

Myocardial Infarction Risk Due to Aircraft, Road, and Rail Traffic Noise.

Science.gov (United States)

Seidler, Andreas; Wagner, Mandy; Schubert, Melanie; Dröge, Patrik; Pons-Kühnemann, Jörn; Swart, Enno; Zeeb, Hajo; Hegewald, Janice

2016-06-17

Traffic noise can induce stress reactions that have effects on the cardiovascular system. The exposure-risk relationship between aircraft, road, and rail traffic noise and myocardial infarction is currently unknown. 19 632 patients from the Rhine-Main region of Germany who were diagnosed with myocardial infarction in the years 2006-2010 were compared with 834 734 control subjects. The assignment of persons to groups was performed on the basis of billing and prescription data from three statutory health insurance carriers. The exposure of all insurees to aircraft, road, and rail traffic noise in 2005 was determined from their residence addresses. As estimators of risk, odds ratios (OR) were calculated by logistic regression analysis, with adjustment for age, sex, regional social status variables, and individual social status (if available). The evaluation was performed on the basis of the continuous 24-hour noise level and the categorized noise level (in 5 decibel classes). The linear model revealed a statistically significant risk increase due to road noise (2.8% per 10 dB rise, 95% confidence interval [1.2; 4.5]) and railroad noise (2.3% per 10 dB rise [0.5; 4.2]), but not airplane noise. Airplane noise levels of 60 dB and above were associated with a higher risk of myocardial infarction (OR 1.42 [0.62; 3.25]). This higher risk is statistically significant if the analysis is restricted to patients who had died of myocardial infarction by 2014/2015 (OR 2.70 [1.08; 6.74]. In this subgroup, the risk estimators for all three types of traffic noise were of comparable magnitude (3.2% to 3.9% per 10 dB rise in noise level). In this study, a substantial proportion of the population was exposed to traffic noise levels that were associated with an albeit small increase in the risk of myocardial infarction. These findings underscore the importance of effective traffic noise prevention.

Anticipated Effectiveness of Active Noise Control in Propeller Aircraft Interiors as Determined by Sound Quality Tests

Science.gov (United States)

Powell, Clemans A.; Sullivan, Brenda M.

2004-01-01

Two experiments were conducted, using sound quality engineering practices, to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller aircraft. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Although the results of the two tests were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference.

Effects of nocturnal aircraft noise on sleep: results from the ''quiet air traffic'' project; Wirkungen des Nachtfluglaerms auf den Schlaf: Ergebnisse aus dem Projekt ''Leiser Flugverkehr''

Energy Technology Data Exchange (ETDEWEB)

Samel, A.; Basner, M.; Maass, H.; Mueller, U.; Quehl, J.; Wenzel, J. [Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) in der Helmholtz-Gemeinschaft (HGF), Inst. fuer Luft- und Raumfahrtmedizin, Koeln (Germany)

2005-07-01

In 192 sleep-healthy subjects (18 to 65 y) effects of nocturnal aircraft noise on sleep, stress, performance and subjective factors were investigated in 2240 nights under laboratory and field conditions. In the sleep lab, 112 volunteers were subjected to aircraft noise events by varying numbers and noise levels during 9 nights within a period of 13 nights. 16 further subjects served as control group (i.e. without any noise). 64 subjects were studied in the vicinity of Cologne-Bonn airport during 9 nights. Polysomnographical and acoustical recordings, determination of excretion rates of stress hormones from night urines, performance tests and questionnaires were conducted during all days for the assessment of nocturnal aircraft noise effects. By simultaneous recording of electrophysiological and acoustical data the probability of noise induced awakenings was estimated. Performance and most of psychological parameters did not show significant dose-effect relationships, whereas annoyance did. Epinephrine and norepinephrine did not change under aircraft noise, cortisol did change only in the lab. In the lab, a comparison between all noisy nights and noise-free baseline nights exhibited a non-significant 2-min. reduction of sleep and a 4-min. decrease of slow-wave sleep. In the field, awakenings caused by aircraft noise were detected above a threshold of 33 dB(A) ''at the sleeper's ear''. All effects were much less pronounced in the field than in the lab. For the first time, precise dose-effect curves between maximum aircraft noise event levels and electrophysiologically detectable awakenings, and a threshold were empirically established. The results of these studies broadens the knowledge on aircraft noise induced sleep disturbances and immediate consequences for the next day. (orig.)

Aircraft noise prediction program theoretical manual: Rotorcraft System Noise Prediction System (ROTONET), part 4

Science.gov (United States)

Weir, Donald S.; Jumper, Stephen J.; Burley, Casey L.; Golub, Robert A.

1995-01-01

This document describes the theoretical methods used in the rotorcraft noise prediction system (ROTONET), which is a part of the NASA Aircraft Noise Prediction Program (ANOPP). The ANOPP code consists of an executive, database manager, and prediction modules for jet engine, propeller, and rotor noise. The ROTONET subsystem contains modules for the prediction of rotor airloads and performance with momentum theory and prescribed wake aerodynamics, rotor tone noise with compact chordwise and full-surface solutions to the Ffowcs-Williams-Hawkings equations, semiempirical airfoil broadband noise, and turbulence ingestion broadband noise. Flight dynamics, atmosphere propagation, and noise metric calculations are covered in NASA TM-83199, Parts 1, 2, and 3.

Aircrafts' taxi noise. Sound power level and directivity frequency band results

NARCIS (Netherlands)

Asensio, C.; Pavón, I.; Ruiz, M.; Pagan Munoz, Raul; Recuero, M.

2009-01-01

When noise mapping airports, the main noise sources are take offs and landings. But aircrafts' taxi noise can also be important, and should be considered, for instance when there are residential buildings near the airport's terminal. Main prediction tools, like Integrated Noise Model (INM), do not

Effects of acoustic treatment on the interior noise levels of a twin-engine propeller aircraft - Experimental flight results and theoretical predictions

Science.gov (United States)

Beyer, T. B.; Powell, C. A.; Daniels, E. F.; Pope, L. D.

1984-01-01

In-flight noise level measurements were made within two cabin configurations of a general aviation business aircraft. The Fairchild Merlin IVC twin-engine aircraft was tested with bare walls and fiberglass insulation and in an executive trim configuration. Narrow-band and octave format data were subjected to analyses which permitted identification of the blade passage harmonics (BPH). Cabin noise level reductions (insertion losses) due to added insulation varied with position in the cabin, the BPH number, cabin pressure, and engine torque. The measurements were closely predicted using the propeller aircraft interior noise (PAIN) mode.

Nuisance Caused by Aircraft Noise in the Vicinity of Tehran International Airport

Directory of Open Access Journals (Sweden)

Stan Frost

1999-03-01

Full Text Available Noise measurement and social questionnaire surveys in three residential areas around Mehrabad International Airport (Tehran, Iran were based upon randomly selected dwellings in each area. A total of 193 individuals responded and many are annoyed and dissatisfied with aircraft noise and in consequence they would like to move. Aircraft noise is the strongest negative environmental factor affecting the residents in the vicinity of Mehrabad Airport and it could be a hazard for their health.

Determination of aircraft noise variability using an acoustic camera

NARCIS (Netherlands)

Merino Martinez, R.; Snellen, M.; Simons, D.G.

2016-01-01

Nowadays, aircraft noise is one of the major problems to be dealt with by the aerospace industry and especially suffered by the residents living in the vicinities of airports. The enforcement of noise control environmental laws around airports is hindered due to the large variability observed in the

Updating working memory in aircraft noise and speech noise causes different fMRI activations.

Science.gov (United States)

Saetrevik, Bjørn; Sörqvist, Patrik

2015-02-01

The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. © 2014 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Aircraft Interior Noise Control Using Distributed Piezoelectric Actuators

Science.gov (United States)

Sun, Jian Q.

1996-01-01

Developing a control system that can reduce the noise and structural vibration at the same time is an important task. This talk presents one possible technical approach for accomplishing this task. The target application of the research is for aircraft interior noise control. The emphasis of the present approach is not on control strategies, but rather on the design of actuators for the control system. In the talk, a theory of distributed piezoelectric actuators is introduced. A uniform cylindrical shell is taken as a simplified model of fuselage structures to illustrate the effectiveness of the design theory. The actuators developed are such that they can reduce the tonal structural vibration and interior noise in a wide range of frequencies. Extensive computer simulations have been done to study various aspects of the design theory. Experiments have also been conducted and the test results strongly support the theoretical development.

Structureborne noise investigations of a twin engine aircraft

Science.gov (United States)

Garrelick, J. M.; Cole, J. E., III; Martini, K.

1986-01-01

The interior noise of aircraft powered by advanced turbo-prop concepts is likely to have nonnegligible contributions from structureborne paths, these paths being those involving propeller loads transmitted to the structures of the lifting surfaces. As a means of examining these paths, structural measurements have been performed on a small twin-engine aircraft, and in addition analytical models of the structure have been developed. In this paper results from both portions of this study are presented.

Assessment of engine noise shielding by the wings of current turbofan aircraft

NARCIS (Netherlands)

Alves Vieira, A.E.; Snellen, M.; Simons, D.G.; Gibbs, B.

2017-01-01

The shielding of engine noise by the aircraft wings and fuselage can lead to a significant reduction on perceived noise on ground. Most research on noise shielding is focused on BlendedWing Body (BWB) configurations because of the large dimension of the fuselage. However, noise shielding is also

The Insulation of Houses against Noise from Aircraft in Flight.

Science.gov (United States)

Scholes, W. E.; Parkin, P. H.

Three groups of traditional houses were insulated against aircraft noise by double glazing and installing sound attenuating ventilator units. For upper floor rooms of two story houses, overall insulations of 35-40 dB were obtainable, providing transmission through the roofs and down flues were also reduced. The noise levels caused by ventilator…

Using the effect of alcohol as a comparison to illustrate the detrimental effects of noise on performance

Directory of Open Access Journals (Sweden)

Brett R.C Molesworth

2013-01-01

Full Text Available The aim of the present research is to provide a user-friendly index of the relative impairment associated with noise in the aircraft cabin. As such, the relative effect of noise, at a level typical of an aircraft cabin was compared with varying levels of alcohol intoxication in the same subjects. Since the detrimental effect of noise is more pronounced on non-native speakers, both native English and non-native English speakers featured in the study. Noise cancelling headphones were also tested as a simple countermeasure to mitigate the effect of noise on performance. A total of 32 participants, half of which were non-native English speakers, completed a cued recall task in two alcohol conditions (blood alcohol concentration 0.05 and 0.10 and two audio conditions (audio played through the speaker and noise cancelling headphones. The results revealed that aircraft noise at 65 dB (A negatively affected performance to a level comparable to alcohol intoxication of 0.10. The results also supported previous research that reflects positively on the benefits of noise cancelling headphones in reducing the effects of noise on performance especially for non-native English speakers. These findings provide for personnel involved in the aviation industry, a user-friendly index of the relative impairment associated with noise in the aircraft cabin as compared with the effects of alcohol. They also highlight the benefits of a simple countermeasure such as noise cancelling headphones in mitigating some of the detrimental effects of noise on performance.

Noise Reduction Efforts for Special Operations C-130 Aircraft Using Active Synchrophaser Control

National Research Council Canada - National Science Library

Hammond, Daryl; McKinley, Richard; Hale, Bill

1998-01-01

.... A more complicated approach uses an active noise cancellation (ANC) system, which offers improved performance that can augment passive methods to significantly reduce both internal and external aircraft noise...

Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

Science.gov (United States)

Revell, J. D.; Balena, F. J.; Koval, L. R.

1980-01-01

The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

Evaluation of a Hydrogen Fuel Cell Powered Blended-Wing-Body Aircraft Concept for Reduced Noise and Emissions

Science.gov (United States)

Guynn, Mark D.; Freh, Joshua E.; Olson, Erik D.

2004-01-01

This report describes the analytical modeling and evaluation of an unconventional commercial transport aircraft concept designed to address aircraft noise and emission issues. A blended-wing-body configuration with advanced technology hydrogen fuel cell electric propulsion is considered. Predicted noise and emission characteristics are compared to a current technology conventional configuration designed for the same mission. The significant technology issues which have to be addressed to make this concept a viable alternative to current aircraft designs are discussed. This concept is one of the "Quiet Green Transport" aircraft concepts studied as part of NASA's Revolutionary Aerospace Systems Concepts (RASC) Program. The RASC Program was initiated to develop revolutionary concepts that address strategic objectives of the NASA Enterprises, such as reducing aircraft noise and emissions, and to identify advanced technology requirements for the concepts.

Cardiovascular effects of environmental noise: Research in Germany

Directory of Open Access Journals (Sweden)

Christian Maschke

2011-01-01

Full Text Available Research on systematic noise effects started in Germany back in the fifties with basic experimental studies on humans. As a result, noise was classified as a non-specific stressor, which could cause an ergotropic activation of the complete organism. In the light of this background research a hypothesis was proposed that long-term noise exposure could have an adverse effect on health. This hypothesis was further supported by animal studies. Since the sixties, the adverse effects of chronic road traffic noise exposure were further examined in humans with the help of epidemiological studies. More epidemiological aircraft noise studies followed in the 1970s and thereafter. The sample size was increased, relevant confounding factors were taken into account, and the exposure and health outcomes were investigated objectively and with higher quality measures. To date, more than 20 German epidemiological traffic noise studies have focused on noise-induced health effects, mainly on the cardiovascular system. In particular, the newer German noise studies demonstrate a clear association between residential exposure to traffic noise (particularly night noise and cardiovascular outcomes. Nevertheless, additional research is needed, particularly on vulnerable groups and multiple noise exposures. The epidemiological findings have still not been fully considered in German regulations, particularly for aircraft noise. The findings, however, were taken into account in national recommendations. The Federal Environment Agency recommends noise rating levels of 65 dB(A for the day and 55 dB(A for the night, as a short-term goal. In the medium term, noise rating levels of 60 / 50 (day, night should be reached and noise rating levels of 55 / 45 in the long run.

Aircraft noise effects on sleep: a systematic comparison of EEG awakenings and automatically detected cardiac activations

International Nuclear Information System (INIS)

Basner, Mathias; Müller, Uwe; Elmenhorst, Eva-Maria; Kluge, Götz; Griefahn, Barbara

2008-01-01

Polysomnography is the gold standard for investigating noise effects on sleep, but data collection and analysis are sumptuous and expensive. We recently developed an algorithm for the automatic identification of cardiac activations associated with cortical arousals, which uses heart rate information derived from a single electrocardiogram (ECG) channel. We hypothesized that cardiac activations can be used as estimates for EEG awakenings. Polysomnographic EEG awakenings and automatically detected cardiac activations were systematically compared using laboratory data of 112 subjects (47 male, mean ± SD age 37.9 ± 13 years), 985 nights and 23 855 aircraft noise events (ANEs). The probability of automatically detected cardiac activations increased monotonically with increasing maximum sound pressure levels of ANEs, exceeding the probability of EEG awakenings by up to 18.1%. If spontaneous reactions were taken into account, exposure–response curves were practically identical for EEG awakenings and cardiac activations. Automatically detected cardiac activations may be used as estimates for EEG awakenings. More investigations are needed to further validate the ECG algorithm in the field and to investigate inter-individual differences in its ability to predict EEG awakenings. This inexpensive, objective and non-invasive method facilitates large-scale field studies on the effects of traffic noise on sleep

Propeller installation effects on turboprop aircraft acoustics

Science.gov (United States)

Chirico, Giulia; Barakos, George N.; Bown, Nicholas

2018-06-01

Propeller installation options for a twin-engined turboprop aircraft are evaluated at cruise conditions, aiming to identify the quieter configuration. Computational fluid dynamics is used to investigate the near-field acoustics and transfer functions are employed to estimate the interior cabin noise. Co-rotating and counter-rotating installation options are compared. The effect of propeller synchrophasing is also considered. The employed method captures the complexity of the acoustic field generated by the interactions of the propeller sound fields among each other and with the airframe, showing also the importance of simulating the whole problem to predict the actual noise on a flying aircraft. Marked differences among the various layouts are observed. The counter-rotating top-in option appears the best in terms of acoustics, the top-out propeller rotation leading to louder noise because of inflow conditions and the occurrence of constructive acoustic interferences. Synchrophasing is shown to be beneficial for co-rotating propellers, specially regarding the interior noise, because of favorable effects in the interaction between the propeller direct sound field and the noise due to the airframe. An angle closer to the maximum relative blade shift was found to be the best choice, yielding, however, higher sound levels than those provided by the counter-rotating top-in layout.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Effects on Sleep

Science.gov (United States)

McGuire, Sarah

2018-01-01

To evaluate the quality of available evidence on the effects of environmental noise exposure on sleep a systematic review was conducted. The databases PSYCINFO, PubMed, Science Direct, Scopus, Web of Science and the TNO Repository were searched for non-laboratory studies on the effects of environmental noise on sleep with measured or predicted noise levels and published in or after the year 2000. The quality of the evidence was assessed using GRADE criteria. Seventy four studies predominately conducted between 2000 and 2015 were included in the review. A meta-analysis of surveys linking road, rail, and aircraft noise exposure to self-reports of sleep disturbance was conducted. The odds ratio for the percent highly sleep disturbed for a 10 dB increase in Lnight was significant for aircraft (1.94; 95% CI 1.61–2.3), road (2.13; 95% CI 1.82–2.48), and rail (3.06; 95% CI 2.38–3.93) noise when the question referred to noise, but non-significant for aircraft (1.17; 95% CI 0.54–2.53), road (1.09; 95% CI 0.94–1.27), and rail (1.27; 95% CI 0.89–1.81) noise when the question did not refer to noise. A pooled analysis of polysomnographic studies on the acute effects of transportation noise on sleep was also conducted and the unadjusted odds ratio for the probability of awakening for a 10 dBA increase in the indoor Lmax was significant for aircraft (1.35; 95% CI 1.22–1.50), road (1.36; 95% CI 1.19–1.55), and rail (1.35; 95% CI 1.21–1.52) noise. Due to a limited number of studies and the use of different outcome measures, a narrative review only was conducted for motility, cardiac and blood pressure outcomes, and for children’s sleep. The effect of wind turbine and hospital noise on sleep was also assessed. Based on the available evidence, transportation noise affects objectively measured sleep physiology and subjectively assessed sleep disturbance in adults. For other outcome measures and noise sources the examined evidence was conflicting or only emerging

A Lightweight Loudspeaker for Aircraft Communications and Active Noise Control

Science.gov (United States)

Warnaka, Glenn E.; Kleinle, Mark; Tsangaris, Parry; Oslac, Michael J.; Moskow, Harry J.

1992-01-01

A series of new, lightweight loudspeakers for use on commercial aircraft has been developed. The loudspeakers use NdFeB magnets and aluminum alloy frames to reduce the weight. The NdFeB magnet is virtually encapsulated by steel in the new speaker designs. Active noise reduction using internal loudspeakers was demonstrated to be effective in 1983. A weight, space, and cost efficient method for creating the active sound attenuating fields is to use the existing cabin loudspeakers for both communication and sound attenuation. This will require some additional loudspeaker design considerations.

Recent technologies for reduction of aircraft propulsion noise. Kokuki engine soon teigenka no saikin no gijutsu shinpo ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, H [National Aerospace Lab., Chofu, Tokyo (Japan)

1994-03-10

Inside the jet engine, the propulsion engine for an aircraft, a high speed air current is flowing, and the rotors such as the fan, compress or, turbine and so forth are rotating with a high speed in its flowing current. The flow itself in which a high speed exhaust jet is discharged in the air from engine exhaust port, and the aerodynamic noise generated by an interaction of the flow with the material bodies are the main noise sources of the aircraft engine. Because the supersonic planes are necessary to fly with mach number 2 - 3 during cruising, the turbojet engine with a large jet exhaust speed or the low bypass ratio turbofan engine is selected. Since a noise reduction by reducing the jet exhaust speed, which was an effective measure for the high subsonic speed passenger plane, can not be applied, a reduction of the supersonic jet noise, which is hard to be reduced, becomes a necessity. In addition, in recent years, a research and development of the advanced turbo prop (ATP) aircraft with a further higher thrust efficiency are advanced as well. The aerodynamical noise reduction technologies of these engines for supersonic airplanes are summarized. 14 refs., 11 figs., 1 tab.

Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

Science.gov (United States)

Fuller, C. R.

1998-01-01

The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

Compact, Lightweight, Ceramic Matrix Composite (CMC) Based Acoustic Liners for Reducing Subsonic Jet Aircraft Engine Noise

Science.gov (United States)

Kiser, J. Douglas; Grady, Joseph E.; Miller, Christopher J.; Hultgren, Lennart S.; Jones, Michael G.

2016-01-01

Recent developments have reduced fan and jet noise contributions to overall subsonic aircraft jet-engine noise. Now, aircraft designers are turning their attention toward reducing engine core noise. The NASA Glenn Research Center and NASA Langley Research Center have teamed to investigate the development of a compact, lightweight acoustic liner based on oxide/oxide ceramic matrix composite (CMC) materials. The NASA team has built upon an existing oxide/oxide CMC sandwich structure concept that provides monotonal noise reduction. Oxide/oxide composites have good high temperature strength and oxidation resistance, which could allow them to perform as core liners at temperatures up to 1000C (1832F), and even higher depending on the selection of the composite constituents. NASA has initiated the evaluation of CMC-based liners that use cells of different lengths (variable-depth channels) or effective lengths to achieve broadband noise reduction. Reducing the overall liner thickness is also a major goal, to minimize the volume occupied by the liner. As a first step toward demonstrating the feasibility of our concepts, an oxide/oxide CMC acoustic testing article with different channel lengths was tested. Our approach, summary of test results, current status, and goals for the future are reported.

Aircraft Noise Perception Study in Brazil: A Perspective on Airport Sustainable Growth and Environmental Awareness

Science.gov (United States)

deArantesGomesEller, Rogerio; Urbina, Ligia Maria Soto; Porto, Protogenes Pires

2003-01-01

Aircraft noise perception is related to several variables that are tangible and objective, such as the number of operations, flight schedules. Other variables, instead, are more subjective, such as preferences. However, although their elusiveness, they contribute to determine the individuals' perception of this type of externality. Despite the fact that the complaints related to aeronautical noise have been registered since the decade of 50, it has been observed that the perception of noise seems to have grown, especially since the 80's. It has been argued that this change in noise perception has its roots on the accelerated expansion of air traffic. But, it is necessary to point out the important role played on modeling preferences, by the growing environmental conscience and the higher welfare and quality of life standards and expectations. In that context, the main objective of this paper is to study the aeronautical noise perception in the neighborhoods of the Aeroporto Internacional de Sao Paulo - AISP (the biggest airport of South America). Specifically, it analyzes the relationship between aircraft noise perception and social class, which is expected to be positive. Since noise perception is an intangible variable, this study chose as a proxy the value losses of residential properties, caused by aeronautical noise. The variable social class has been measured utilizing average per capita income of the population who live nearby the airport. The comparison of both, the lowest and the highest social class suggests that the relationship between social class and noise perception is positive in the AISP region. Moreover, it was observed that all social classes are very susceptible to aircraft noise annoyance. In fact, the magnitude of the noise perception proxy for both social classes -the residential value losses- was found to be comparable to levels encountered in developed countries.

Updating working memory in aircraft noise and speech causes different fMRI activations

OpenAIRE

Sætrevik, Bjørn; Sörqvist, Patrik

2014-01-01

The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between ?substitution processes,? which involve adding new items to the working memory representation and suppressing old items, and ?exclusion processes,? which involve rejecting new items and maintaining an intact memory set. The cu...

Brain-stem evoked potentials and noise effects in seagulls.

Science.gov (United States)

Counter, S A

1985-01-01

Brain-stem auditory evoked potentials (BAEP) recorded from the seagull were large-amplitude, short-latency, vertex-positive deflections which originate in the eighth nerve and several brain-stem nuclei. BAEP waveforms were similar in latency and configurations to that reported for certain other lower vertebrates and some mammals. BAEP recorded at several pure tone frequencies throughout the seagull's auditory spectrum showed an area of heightened auditory sensitivity between 1 and 3 kHz. This range was also found to be the primary bandwidth of the vocalization output of young seagulls. Masking by white noise and pure tones had remarkable effects on several parameters of the BAEP. In general, the tone- and click-induced BAEP were either reduced or obliterated by both pure tone and white noise maskers of specific signal to noise ratios and high intensity levels. The masking effects observed in this study may be related to the manner in which seagulls respond to intense environmental noise. One possible conclusion is that intense environmental noise, such as aircraft engine noise, may severely alter the seagull's localization apparatus and induce sonogenic stress, both of which could cause collisions with low-flying aircraft.

Military Tactical Aircraft Engine Noise Matching to Infrared Signatures

Science.gov (United States)

2016-12-16

Jet engine exhaust plumes also exhibit emission and absorption of radiation from their emitted chemical species, occurring at discrete spectra...Modulation,” Naval Postgraduate School MS thesis (1990). [8] Sinha, N., Ungewitter, R. J., Kenzakowski, D. C., and Seiner, J. M., “Gas Turbine Engine Jet...FINAL REPORT Military Tactical Aircraft Engine Noise Matching to Infrared Signatures SERDP Project WP-2404 JANUARY 2016 Dr

Optimization of actuator arrays for aircraft interior noise control

Science.gov (United States)

Cabell, R. H.; Lester, H. C.; Mathur, G. P.; Tran, B. N.

1993-01-01

A numerical procedure for grouping actuators in order to reduce the number of degrees of freedom in an active noise control system is evaluated using experimental data. Piezoceramic actuators for reducing aircraft interior noise are arranged into groups using a nonlinear optimization routine and clustering algorithm. An actuator group is created when two or more actuators are driven with the same control input. This procedure is suitable for active control applications where actuators are already mounted on a structure. The feasibility of this technique is demonstrated using measured data from the aft cabin of a Douglas DC-9 fuselage. The measured data include transfer functions between 34 piezoceramic actuators and 29 interior microphones and microphone responses due to the primary noise produced by external speakers. Control inputs for the grouped actuators were calculated so that a cost function, defined as a quadratic pressure term and a penalty term, was a minimum. The measured transfer functions and microphone responses are checked by comparing calculated noise reductions with measured noise reductions for four frequencies. The grouping procedure is then used to determine actuator groups that improve overall interior noise reductions by 5.3 to 15 dB, compared to the baseline experimental configuration.

The effect on recognition memory of noise cancelling headphones in a noisy environment with native and nonnative speakers

Directory of Open Access Journals (Sweden)

Brett R C Molesworth

2014-01-01

Full Text Available Noise has the potential to impair cognitive performance. For nonnative speakers, the effect of noise on performance is more severe than their native counterparts. What remains unknown is the effectiveness of countermeasures such as noise attenuating devices in such circumstances. Therefore, the main aim of the present research was to examine the effectiveness of active noise attenuating countermeasures in the presence of simulated aircraft noise for both native and nonnative English speakers. Thirty-two participants, half native English speakers and half native German speakers completed four recognition (cued recall tasks presented in English under four different audio conditions, all in the presence of simulated aircraft noise. The results of the research indicated that in simulated aircraft noise at 65 dB(A, performance of nonnative English speakers was poorer than for native English speakers. The beneficial effects of noise cancelling headphones in improving the signal to noise ratio led to an improved performance for nonnative speakers. These results have particular importance for organizations operating in a safety-critical environment such as aviation.

European Blackbirds Exposed to Aircraft Noise Advance Their Chorus, Modify Their Song and Spend More Time Singing

Directory of Open Access Journals (Sweden)

Javier Sierro

2017-06-01

Full Text Available Noise pollution has a strong impact on wildlife by disrupting vocal communication or inducing physiological stress. Songbirds are particularly reliant on vocal communication as they use song during territorial and sexual interactions. Birds living in noisy environments have been shown to change the acoustic and temporal parameters of their song presumably to maximize signal transmissibility. Also, research shows that birds advance their dawn chorus in urban environments to avoid the noisiest hours, but little is known on the consequences of these changes in the time they spent singing at dawn. Here we present a comprehensive view of the European blackbird singing behavior living next to a large airport in Madrid, using as a control a population living in a similar but silent forest. Blackbird song is composed of two parts: a series of loud low-frequency whistles (motif and a final flourish (twitter. We found that airport blackbirds were more likely to sing songs without the twitter part. Also, when songs included a twitter part, airport blackbirds used a smaller proportion of song for the twitter than control blackbirds. Interestingly, our results show no differences in song frequency between airport and control populations. However airport blackbirds not only sang earlier but also increased the time they spent singing when chorus and aircraft traffic overlapped on time. This effect disappeared as the season progressed and the chorus and the aircraft traffic schedule were separated on time. We propose that the typical urban upshift in frequency might not be useful under the noise conditions and landscape structure found near airports. We suggest that the modifications in singing behavior induced by aircraft noise may be adaptive and that they are specific to airport acoustic habitat. Moreover, we found that adjustment of singing activity in relation to noise is plastic and possibly optimized to cope with aircraft traffic activity. In a

Real-Time Noise Prediction of V/STOL Aircraft in Maneuvering Flight, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This proposal outlines a plan for enhancing and integrating new breakthrough technologies to provide accurate real-time noise prediction of V/STOL aircraft in...

Levels And Spectra Of Aircraft Noise And People\\'s Reactions In ...

African Journals Online (AJOL)

A study of sound levels and spectral distribution as well as people\\'s reactions to aircraft noise in three Nigerian international airports have been conducted. The study comprised physical measurements and social survey. Results show that maximum octave band pressure levels (BPLs) for Margaret Ekpo, Port Harcourt and ...

Nonlinear acoustic propagation of launch vehicle and military jet aircraft noise

Science.gov (United States)

Gee, Kent L.

2010-10-01

The noise from launch vehicles and high-performance military jet aircraft has been shown to travel nonlinearly as a result of an amplitude-dependent speed of sound. Because acoustic pressure compressions travel faster than rarefactions, the waveform steepens and shocks form. This process results in a very different (and readily audible) noise signature and spectrum than predicted by linear models. On-going efforts to characterize the nonlinearity using statistical and spectral measures are described with examples from recent static tests of solid rocket boosters and the F-22 Raptor.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Annoyance

Directory of Open Access Journals (Sweden)

Rainer Guski

2017-12-01

Full Text Available Background: This paper describes a systematic review and meta-analyses on effects of environmental noise on annoyance. The noise sources include aircraft, road, and rail transportation noise as well as wind turbines and noise source combinations. Objectives: Update knowledge about effects of environmental noise on people living in the vicinity of noise sources. Methods: Eligible were published studies (2000–2014 providing comparable acoustical and social survey data including exposure-response functions between standard indicators of noise exposure and standard annoyance responses. The systematic literature search in 20 data bases resulted in 62 studies, of which 57 were used for quantitative meta-analyses. By means of questionnaires sent to the study authors, additional study data were obtained. Risk of bias was assessed by means of study characteristics for individual studies and by funnel plots to assess the risk of publication bias. Main Results: Tentative exposure-response relations for percent highly annoyed residents (%HA in relation to noise levels for aircraft, road, rail, wind turbine and noise source combinations are presented as well as meta-analyses of correlations between noise levels and annoyance raw scores, and the OR for increase of %HA with increasing noise levels. Quality of evidence was assessed using the GRADE terminology. The evidence of exposure-response relations between noise levels and %HA is moderate (aircraft and railway or low (road traffic and wind turbines. The evidence of correlations between noise levels and annoyance raw scores is high (aircraft and railway or moderate (road traffic and wind turbines. The evidence of ORs representing the %HA increase by a certain noise level increase is moderate (aircraft noise, moderate/high (road and railway traffic, and low (wind turbines. Strengths and Limitations: The strength of the evidence is seen in the large total sample size encompassing the included studies (e

Noise-induced annoyance from transportation noise: short-term responses to a single noise source in a laboratory.

Science.gov (United States)

Kim, Jaehwan; Lim, Changwoo; Hong, Jiyoung; Lee, Soogab

2010-02-01

An experimental study was performed to compare the annoyances from civil-aircraft noise, military-aircraft noise, railway noise, and road-traffic noise. Two-way within-subjects designs were applied in this research. Fifty-two subjects, who were naive listeners, were given various stimuli with varying levels through a headphone in an anechoic chamber. Regardless of the frequency weighting network, even under the same average energy level, civil-aircraft noise was the most annoying, followed by military-aircraft noise, railway noise, and road-traffic noise. In particular, penalties in the time-averaged, A-weighted sound level (TAL) of about 8, 5, and 5 dB, respectively, were found in the civil-aircraft, military-aircraft, and railway noises. The reason could be clarified through the high-frequency component and the variability in the level. When people were exposed to sounds with the same maximum A-weighted level, a railway bonus of about 3 dB was found. However, transportation noise has been evaluated by the time-averaged A-weighted level in most countries. Therefore, in the present situation, the railway bonus is not acceptable for railway vehicles with diesel-electric engines.

Noise transmission through sidewall treatments applicable to twin-engine turboprop aircraft

Science.gov (United States)

Grosveld, F. W.

1983-04-01

The noise transmission loss characteristics of the sidewall treatment in the propeller plane of a twin-engine turboprop aircraft are experimentally investigated in the NASA Langley Research Center Transmission Loss Facility. The sound attenuation properties of the individual elements of this treatment are evaluated showing least noise transmission loss in the low frequencies (below 500 Hz) where the excitation levels at the propeller blade passage frequency and the first few harmonics are highest. It is shown that single and double wall resonances play an important role in the noise transmission loss values of the treatment at these low frequencies suggesting that a limp mass with a very low resonance frequency serves better as a trim panel than a trim panel having a high structural stiffness. It is indicated that the window structures might be a potential noise control problem.

Measurements techniques for transportation noise

International Nuclear Information System (INIS)

Brambilla, G.

2001-01-01

The noise from transport systems (roads, railways and aircraft) are increasing more and more both in space and in time and, therefore, they are still the major factor responsible for environmental noise pollution. The population exposed to transport noise is also increasing, and the corresponding health effects on people (i.e. annoyance and sleep disturbance) become more severe. Due to this current situation international and national legislation has been issued and implemented to reduce the harmful effects of such noise. This paper describes the techniques prescribed by recent Italian legislation to measure road, railway and aircraft noise. (author)

High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

Directory of Open Access Journals (Sweden)

Minarma Siagian

2009-12-01

Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

Airframe Noise Prediction of a Full Aircraft in Model and Full Scale Using a Lattice Boltzmann Approach

Science.gov (United States)

Fares, Ehab; Duda, Benjamin; Khorrami, Mehdi R.

2016-01-01

Unsteady flow computations are presented for a Gulfstream aircraft model in landing configuration, i.e., flap deflected 39deg and main landing gear deployed. The simulations employ the lattice Boltzmann solver PowerFLOW(Trademark) to simultaneously capture the flow physics and acoustics in the near field. Sound propagation to the far field is obtained using a Ffowcs Williams and Hawkings acoustic analogy approach. Two geometry representations of the same aircraft are analyzed: an 18% scale, high-fidelity, semi-span model at wind tunnel Reynolds number and a full-scale, full-span model at half-flight Reynolds number. Previously published and newly generated model-scale results are presented; all full-scale data are disclosed here for the first time. Reynolds number and geometrical fidelity effects are carefully examined to discern aerodynamic and aeroacoustic trends with a special focus on the scaling of surface pressure fluctuations and farfield noise. An additional study of the effects of geometrical detail on farfield noise is also documented. The present investigation reveals that, overall, the model-scale and full-scale aeroacoustic results compare rather well. Nevertheless, the study also highlights that finer geometrical details that are typically not captured at model scales can have a non-negligible contribution to the farfield noise signature.

Emotionality in response to aircraft noise: A report of development work

Science.gov (United States)

Klaus, P. A.

1975-01-01

A literature search and pilot study conducted to investigate the topic of emotional response to aircraft noise are described. A Tell-A-Story Technique was developed for use in the pilot study which required respondents to make up stories for a series of aircraft-related and non-aircraft-related pictures. A content analysis of these stories was made. The major finding was that response patterns varied among three groups of respondents - those currently living near airports, those who had lived near airports in the past, and those who had never lived near airports. Negative emotional feelings toward aircraft were greatest among respondents who had lived near airports in the past but no longer did. A possible explanation offered for this finding was that people currently living near airports might adapt to the situation by denying some of their negative feelings, which they might feel more free to express after they had moved away from the situation. Other techniques used in the pilot study are also described, including group interviews and a word association task.

Overview of en route noise prediction using a integrated noise model

Science.gov (United States)

2010-04-20

En route aircraft noise is often ignored in aircraft noise modeling because large amounts of noise attenuation due to long propagation distances between the aircraft and the receivers on the ground, reduced power in cruise flight compared to takeoff ...

Aerodynamic Measurements of a Gulfstream Aircraft Model With and Without Noise Reduction Concepts

Science.gov (United States)

Neuhart, Dan H.; Hannon, Judith A.; Khorrami, Mehdi R.

2014-01-01

Steady and unsteady aerodynamic measurements of a high-fidelity, semi-span 18% scale Gulfstream aircraft model are presented. The aerodynamic data were collected concurrently with acoustic measurements as part of a larger aeroacoustic study targeting airframe noise associated with main landing gear/flap components, gear-flap interaction noise, and the viability of related noise mitigation technologies. The aeroacoustic tests were conducted in the NASA Langley Research Center 14- by 22-Foot Subsonic Wind Tunnel with the facility in the acoustically treated open-wall (jet) mode. Most of the measurements were obtained with the model in landing configuration with the flap deflected at 39º and the main landing gear on and off. Data were acquired at Mach numbers of 0.16, 0.20, and 0.24. Global forces (lift and drag) and extensive steady and unsteady surface pressure measurements were obtained. Comparison of the present results with those acquired during a previous test shows a significant reduction in the lift experienced by the model. The underlying cause was traced to the likely presence of a much thicker boundary layer on the tunnel floor, which was acoustically treated for the present test. The steady and unsteady pressure fields on the flap, particularly in the regions of predominant noise sources such as the inboard and outboard tips, remained unaffected. It is shown that the changes in lift and drag coefficients for model configurations fitted with gear/flap noise abatement technologies fall within the repeatability of the baseline configuration. Therefore, the noise abatement technologies evaluated in this experiment have no detrimental impact on the aerodynamic performance of the aircraft model.

Prediction and reduction of aircraft noise in outdoor environments

Science.gov (United States)

Tong, Bao N.

This dissertation investigates the noise due to an en-route aircraft cruising at high altitudes. It offers an improved understanding into the combined effects of atmospheric propagation, ground reflection, and source motion on the impact of en-route aircraft noise. A numerical model has been developed to compute pressure time-histories due to a uniformly moving source above a flat ground surface in the presence of a horizontally stratified atmosphere. For a moving source at high elevations, contributions from a direct and specularly reflected wave are sufficient in predicting the sound field close to the ground. In the absence of wind effects, the predicted sound field from a single overhead flight trajectory can be used to interpolate pressure time histories at all other receiver locations via a simplified ray model for the incoherent sound field. This approach provides an efficient method for generating pressure time histories in a three-dimensional space for noise impact studies. A variety of different noise propagation methods are adapted to a uniformly moving source to evaluate the accuracy and efficiency of their predictions. The techniques include: analytical methods, the Fast Field Program (FFP), and asymptotic analysis methods (e.g., ray tracing and more advanced formulations). Source motion effects are introduced via either a retarded time analysis or a Lorentz transform approach depending on the complexity of the problem. The noise spectrum from a single emission frequency, moving source has broadband characteristics. This is a consequence of the Doppler shift which continuously modifies the perceived frequency of the source as it moves relative to a stationary observer on the ground. Thus, the instantaneous wavefronts must be considered in both the frequency dependent ground impedance model and the atmospheric absorption model. It can be shown that the Doppler factor is invariant along each ray path. This gives rise to a path dependent atmospheric

Enroute NASA/FAA low-frequency propfan test in Alabama (October 1987): A versatile atmospheric aircraft long-range noise prediction system

Science.gov (United States)

Tsouka, Despina G.

In order to obtain a flight-to-static noise prediction of an advanced Turboprop (propfan) Aircraft, FAA went on an elaboration of the data that were measured during a full scale measuring program that was conducted by NASA and FAA/DOT/TSC on October 1987 in Alabama. The elaboration process was based on aircraft simulation to a point source, on an atmospheric two dimensional noise model, on the American National Standard algorithm for the calculation of atmospheric absortion, and on the DOT/TSC convention for ground reflection effects. Using the data of the Alabama measurements, the present paper examines the development of a generalized, flexible and more accurate process for the evaluation of the static and flight low-frequency long-range noise data. This paper also examines the applicability of the assumptions made by the Integrated Noise Model about linear propagation, of the three dimensional Hamiltonian Rays Tracing model and of the Weyl-Van der Pol model. The model proposes some assumptions in order to increase the calculations flexibility without significant loss of accuracy. In addition, it proposes the usage of the three dimensional Hamiltonian Rays Tracing model and the Weyl-Van der Pol model in order to increase the accuracy and to ensure the generalization of noise propagation prediction over grounds with variable impedance.

Effects of signal salience and noise on performance and stress in an abbreviated vigil

Science.gov (United States)

Helton, William Stokely

Vigilance or sustained attention tasks traditionally require observers to detect predetermined signals that occur unpredictably over periods of 30 min to several hours (Warm, 1984). These tasks are taxing and have been useful in revealing the effects of stress agents, such as infectious disease and drugs, on human performance (Alluisi, 1969; Damos & Parker, 1994; Warm, 1993). However, their long duration has been an inconvenience. Recently, Temple and his associates (Temple et al., 2000) developed an abbreviated 12-min vigilance task that duplicates many of the findings with longer duration vigils. The present study was designed to explore further the similarity of the abbreviated task to long-duration vigils by investigating the effects of signal salience and jet-aircraft engine noise on performance, operator stress, and coping strategies. Forty-eight observers (24 males and 24 females) were assigned at random to each of four conditions resulting from the factorial combination of signal salience (high and low contrast signals) and background noise (quiet and jet-aircraft noise). As is the case with long-duration vigils (Warm, 1993), signal detection in the abbreviated task was poorer for low salience than for high salience signals. In addition, stress scores, as indexed by the Dundee Stress State Questionnaire (Matthews, Joiner, Gilliland, Campbell, & Falconer, 1999), were elevated in the low as compared to the high salience condition. Unlike longer vigils, however, (Becker, Warm, Dember, & Hancock, 1996), signal detection in the abbreviated task was superior in the presence of aircraft noise than in quiet. Noise also attenuated the stress of the vigil, a result that is counter to previous findings regarding the effects of noise in a variety of other scenarios (Clark, 1984). Examination of observers' coping responses, as assessed by the Coping Inventory for Task Situations (Matthews & Campbell, 1998), indicated that problem-focused coping was the overwhelming

Estimation of directivity and sound power levels emitted by aircrafts during taxiing, for outdoor noise prediction purpose

NARCIS (Netherlands)

Asensio, C.; Pavón, I.; Ruiz, M.; Pagan Munoz, Raul; Recuero, M.

2007-01-01

Integrated noise model (INM) is the most internationally used software to calculate noise levels near airports. Take off, landing or pass by operations can be modeled by INM, but it does not consider aircrafts taxiing, which, in some cases, can be important to accurately evaluate and reduce

Effects of noise and task loading on a communication task loading on a communication task

Science.gov (United States)

Orrell, Dean H., II

Previous research had shown the effect of noise on a single communication task. This research has been criticized as not being representative of a real world situation since subjects allocated all of their attention to only one task. In the present study, the effect of adding a loading task to a standard noise-communication paradigm was investigated. Subjects performed both a communication task (Modified Rhyme Test; House et al. 1965) and a short term memory task (Sternberg, 1969) in simulated levels of aircraft noise (95, 105 and 115 dB overall sound pressure level (OASPL)). Task loading was varied with Sternberg's task by requiring subjects to memorize one, four, or six alphanumeric characters. Simulated aircraft noise was varied between levels of 95, 105 and 115 dB OASPL using a pink noise source. Results show that the addition of Sternberg's task and little effect on the intelligibility of the communication task while response time for the communication task increased.

Research Plans for Improving Understanding of Effects of Very Low-Frequency Noise of Heavy Lift Rotorcraft

Science.gov (United States)

Fidell, Sanford; Horonieff, Richard D.; Schmitz, Fredric H.

2010-01-01

This report reviews the English-language technical literature on infrasonic and low-frequency noise effects; identifies the most salient effects of noise produced by a future large civil tiltrotor aircraft on crew, passengers, and communities near landing areas; and recommends research needed to improve understanding of the effects of such noise on passengers, crew, and residents of areas near landing pads.

Light aircraft sound transmission studies - Noise reduction model

Science.gov (United States)

Atwal, Mahabir S.; Heitman, Karen E.; Crocker, Malcolm J.

1987-01-01

Experimental tests conducted on the fuselage of a single-engine Piper Cherokee light aircraft suggest that the cabin interior noise can be reduced by increasing the transmission loss of the dominant sound transmission paths and/or by increasing the cabin interior sound absorption. The validity of using a simple room equation model to predict the cabin interior sound-pressure level for different fuselage and exterior sound field conditions is also presented. The room equation model is based on the sound power flow balance for the cabin space and utilizes the measured transmitted sound intensity data. The room equation model predictions were considered good enough to be used for preliminary acoustical design studies.

Aircraft interior noise models - Sidewall trim, stiffened structures, and cabin acoustics with floor partition

Science.gov (United States)

Pope, L. D.; Wilby, E. G.; Willis, C. M.; Mayes, W. H.

1983-01-01

As part of the continuing development of an aircraft interior noise prediction model, in which a discrete modal representation and power flow analysis are used, theoretical results are considered for inclusion of sidewall trim, stiffened structures, and cabin acoustics with floor partition. For validation purposes, predictions of the noise reductions for three test articles (a bare ring-stringer stiffened cylinder, an unstiffened cylinder with floor and insulation, and a ring-stringer stiffened cylinder with floor and sidewall trim) are compared with measurements.

Noise control in aeroacoustics; Proceedings of the 1993 National Conference on Noise Control Engineering, NOISE-CON 93, Williamsburg, VA, May 2-5, 1993

Science.gov (United States)

Hubbard, Harvey H. (Editor)

1993-01-01

In the conference over 100 papers were presented in eight sessions: (1) Emission: Noise Sources; (2) Physical Phenomena; (3) Noise ControlElements; (4) Vibration and Shock: Generation, Transmission, Isolation, and Reduction; (5) Immission: Physical Aspects of Environmental Noise; (6) Immission: Effects of Noise; (7) Analysis; and (8) Requirements. In addition, the distinguished lecture series included presentations on the High Speed Civil Transport and on research from the United Kingdom on aircraft noise effects.

The Adverse Effects of Environmental Noise Exposure on Oxidative Stress and Cardiovascular Risk

Science.gov (United States)

Sørensen, Mette; Schmidt, Frank; Schmidt, Erwin; Steven, Sebastian; Kröller-Schön, Swenja; Daiber, Andreas

2018-01-01

Abstract Epidemiological studies have provided evidence that traffic noise exposure is linked to cardiovascular diseases such as arterial hypertension, myocardial infarction, and stroke. Noise is a nonspecific stressor that activates the autonomous nervous system and endocrine signaling. According to the noise reaction model introduced by Babisch and colleagues, chronic low levels of noise can cause so-called nonauditory effects, such as disturbances of activity, sleep, and communication, which can trigger a number of emotional responses, including annoyance and subsequent stress. Chronic stress in turn is associated with cardiovascular risk factors, comprising increased blood pressure and dyslipidemia, increased blood viscosity and blood glucose, and activation of blood clotting factors, in animal models and humans. Persistent chronic noise exposure increases the risk of cardiometabolic diseases, including arterial hypertension, coronary artery disease, diabetes mellitus type 2, and stroke. Recently, we demonstrated that aircraft noise exposure during nighttime can induce endothelial dysfunction in healthy subjects and is even more pronounced in coronary artery disease patients. Importantly, impaired endothelial function was ameliorated by acute oral treatment with the antioxidant vitamin C, suggesting that excessive production of reactive oxygen species contributes to this phenomenon. More recently, we introduced a novel animal model of aircraft noise exposure characterizing the underlying molecular mechanisms leading to noise-dependent adverse oxidative stress-related effects on the vasculature. With the present review, we want to provide an overview of epidemiological, translational clinical, and preclinical noise research addressing the nonauditory, adverse effects of noise exposure with focus on oxidative stress. Antioxid. Redox Signal. 28, 873–908. PMID:29350061

Noise: how can the nuisance be controlled?

Science.gov (United States)

Ollerhead, J B

1973-09-01

Aircraft noise is a major nuisance in residential communities around airports. If the air transport industries are to meet the ever increasing demand for air travel, determined efforts are required now to reduce the burden of noise upon these communities. Significant engine noise reductions have already been achieved in the latest generation of wide-bodied aircraft, and further reductions are being forecast by the engine manufacturers. Regardless of whether there are justifiable grounds for this optimism there are alternative steps to be taken. But the problem is basically an economic rather than a technological one - how much does noise reduction cost and how much can we afford to pay? The various costs of aircraft noise, both monetary and social, are discussed in relation to its effects upon people. Although an economic analysis of the problem is feasible, it is doubtful whether our understanding of the relationships between physical noise levels and human reaction is yet adequate for such purposes. Planning methods for estimating the extent of community noise nuisance are presented, and it is shown that consideration should be given to outlying regions exposed to relatively little aircraft noise.

Aviation Noise Impacts: State of the Science

Directory of Open Access Journals (Sweden)

Mathias Basner

2017-01-01

Full Text Available Noise is defined as “unwanted sound.” Aircraft noise is one, if not the most detrimental environmental effect of aviation. It can cause community annoyance, disrupt sleep, adversely affect academic performance of children, and could increase the risk for cardiovascular disease of people living in the vicinity of airports. In some airports, noise constrains air traffic growth. This consensus paper was prepared by the Impacts of Science Group of the Committee for Aviation Environmental Protection of the International Civil Aviation Organization and summarizes the state of the science of noise effects research in the areas of noise measurement and prediction, community annoyance, children’s learning, sleep disturbance, and health. It also briefly discusses civilian supersonic aircraft as a future source of aviation noise.

Noise and Fuel Burn Reduction Potential of an Innovative Subsonic Transport Configuration

Science.gov (United States)

Guo, Yueping; Nickol, Craig L.; Thomas, Russell H.

2014-01-01

A study is presented for the noise and fuel burn reduction potential of an innovative double deck concept aircraft with two three-shaft direct-drive turbofan engines. The engines are mounted from the fuselage so that the engine inlet is over the main wing. It is shown that such an aircraft can achieve a cumulative Effective Perceived Noise Level (EPNL) about 28 dB below the current aircraft noise regulations of Stage 4. The combination of high bypass ratio engines and advanced wing design with laminar flow control technologies provide fuel burn reduction and low noise levels simultaneously. For example, the fuselage mounted engine position provides more than 4 EPNLdB of noise reduction by shielding the inlet radiated noise. To identify the potential effect of noise reduction technologies on this concept, parametric studies are presented to reveal the system level benefits of various emerging noise reduction concepts, for both engine and airframe noise reduction. These concepts are discussed both individually to show their respective incremental noise reduction potential and collectively to assess their aggregate effects on the total noise. Through these concepts approximately about 8 dB of additional noise reduction is possible, bringing the cumulative noise level of this aircraft to 36 EPNLdB below Stage 4, if the entire suite of noise reduction technologies would mature to practical application. In a final step, an estimate is made for this same aircraft concept but with higher bypass ratio, geared, turbofan engines. With this geared turbofan propulsion system, the noise is estimated to reach as low as 40-42 dB below Stage 4 with a fuel burn reduction of 43-47% below the 2005 best-in-class aircraft baseline. While just short of the NASA N+2 goals of 42 dB and 50% fuel burn reduction, for a 2025 in service timeframe, this assessment shows that this innovative concept warrants refined study. Furthermore, this design appears to be a viable potential future passenger

Field-incidence noise transmission loss of general aviation aircraft double wall configurations

Science.gov (United States)

Grosveld, F. W.

1984-01-01

Theoretical formulations have been developed to describe the transmission of reverberant sound through an infinite, semi-infinite and a finite double panel structure. The model incorporates the fundamental resonance frequencies of each of the panels, the mass-air-mass resonances of the structure, the standing wave resonances in the cavity between the panels and finally the coincidence resonance regions, where the exciting sound pressure wave and flexural waves of each of the panels coincide. It is shown that phase cancellation effects of pressure waves reflected from the cavity boundaries back into the cavity allows the transmission loss of a finite double panel structure to be approximated by a finite double panel mounted in an infinite baffle having no cavity boundaries. Comparison of the theory with high quality transmission loss data yields good agreement in the mass-controlled frequency region. It is shown that the application of acoustic blankets to the double panel structure does not eliminate the mass-air-mass resonances if those occur at low frequencies. It is concluded that this frequency region of low noise transmission loss is a potential interior noise problem area for propeller driven aircraft having a double panel fuselage construction.

The Cost-Effectiveness of Lowering Permissible Noise Levels Around U.S. Airports

Directory of Open Access Journals (Sweden)

Boshen Jiao

2017-12-01

Full Text Available Aircraft noise increases the risk of cardiovascular diseases and mental illness. The allowable limit for sound in the vicinity of an airport is 65 decibels (dB averaged over a 24-h ‘day and night’ period (DNL in the United States. We evaluate the trade-off between the cost and the health benefits of changing the regulatory DNL level from 65 dB to 55 dB using a Markov model. The study used LaGuardia Airport (LGA as a case study. In compliance with 55 dB allowable limit of aircraft noise, sound insulation would be required for residential homes within the 55 dB to 65 dB DNL. A Markov model was built to assess the cost-effectiveness of installing sound insulation. One-way sensitivity analyses and Monte Carlo simulation were conducted to test uncertainty of the model. The incremental cost-effectiveness ratio of installing sound insulation for residents exposed to airplane noise from LGA was $11,163/QALY gained (95% credible interval: cost-saving and life-saving to $93,054/QALY gained. Changing the regulatory standard for noise exposure around airports from 65 dB to 55 dB comes at a very good value.

Noise Considerations for V/STOL Transports

Science.gov (United States)

Kenyon, George C.

1968-01-01

Noise consideration may well be as important a factor in future aircraft concept selection as such economic factors as operating cost and profitability. The impact of noise on some of the design and operational aspects of future V/STOL transports is examined in detail, including consideration of configuration, attitude-control system, lift system, and terminal flight pattern. Extended vertical rise of VTOL aircraft as a method of limiting the intense noise exposure to the terminal area is shown to be only partially effective as well as costly. Comparisons are made of noise contours for conceptual V/STOL transports for several PNdB criteria. The variation in extent of affected area with configuration and criterion emphasizes the importance of establishing an "acceptable" noise level for "city-center" operation.

32 CFR 989.32 - Noise.

Science.gov (United States)

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Noise. 989.32 Section 989.32 National Defense... ANALYSIS PROCESS (EIAP) § 989.32 Noise. Aircraft noise data files used for analysis during EIAP will be... System for Aircraft Noise for military training routes and military operating areas. Guidance on...

Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise

NARCIS (Netherlands)

Salomons, E.M.; Janssen, S.A.

2011-01-01

In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a

Critical Low-Noise Technologies Being Developed for Engine Noise Reduction Systems Subproject

Science.gov (United States)

Grady, Joseph E.; Civinskas, Kestutis C.

2004-01-01

NASA's previous Advanced Subsonic Technology (AST) Noise Reduction Program delivered the initial technologies for meeting a 10-year goal of a 10-dB reduction in total aircraft system noise. Technology Readiness Levels achieved for the engine-noise-reduction technologies ranged from 4 (rig scale) to 6 (engine demonstration). The current Quiet Aircraft Technology (QAT) project is building on those AST accomplishments to achieve the additional noise reduction needed to meet the Aerospace Technology Enterprise's 10-year goal, again validated through a combination of laboratory rig and engine demonstration tests. In order to meet the Aerospace Technology Enterprise goal for future aircraft of a 50- reduction in the perceived noise level, reductions of 4 dB are needed in both fan and jet noise. The primary objectives of the Engine Noise Reduction Systems (ENRS) subproject are, therefore, to develop technologies to reduce both fan and jet noise by 4 dB, to demonstrate these technologies in engine tests, and to develop and experimentally validate Computational Aero Acoustics (CAA) computer codes that will improve our ability to predict engine noise.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Cognition.

Science.gov (United States)

Clark, Charlotte; Paunovic, Katarina

2018-02-07

This systematic review assesses the quality of the evidence across individual studies on the effect of environmental noise (road traffic, aircraft, and train and railway noise) on cognition. Quantitative non-experimental studies of the association between environmental noise exposure on child and adult cognitive performance published up to June 2015 were reviewed: no limit was placed on the start date for the search. A total of 34 papers were identified, all of which were of child populations. 82% of the papers were of cross-sectional design, with fewer studies of longitudinal or intervention design. A range of cognitive outcomes were examined. The quality of the evidence across the studies for each individual noise source and cognitive outcome was assessed using an adaptation of GRADE methodology. This review found, given the predominance of cross-sectional studies, that the quality of the evidence across studies ranged from being of moderate quality for an effect for some outcomes, e.g., aircraft noise effects on reading comprehension and on long-term memory, to no effect for other outcomes such as attention and executive function and for some noise sources such as road traffic noise and railway noise. The GRADE evaluation of low quality evidence across studies for some cognitive domains and for some noise sources does not necessarily mean that there are no effects: rather, that more robust and a greater number of studies are required.

Experimental and theoretical sound transmission. [reduction of interior noise in aircraft

Science.gov (United States)

Roskam, J.; Muirhead, V. U.; Smith, H. W.; Durenberger, D. W.

1978-01-01

The capabilities of the Kansas University- Flight Research Center for investigating panel sound transmission as a step toward the reduction of interior noise in general aviation aircraft were discussed. Data obtained on panels with holes, on honeycomb panels, and on various panel treatments at normal incidence were documented. The design of equipment for panel transmission loss tests at nonnormal (slanted) sound incidence was described. A comprehensive theory-based prediction method was developed and shows good agreement with experimental observations of the stiffness controlled, the region, the resonance controlled region, and the mass-law region of panel vibration.

Acoustical design economic trade off for transport aircraft

Science.gov (United States)

Benito, A.

The effects of ICAO fixed certification limits and local ordinances on acoustic emissions from jets on commercial transport aircraft and costs of operations are explored. The regulations effectively ban some aircraft from operation over populated areas, impose curfews on airports and, in conjunction with local civil aviation rules, levy extra taxes and quotas on noisier equipment. Jet engine manufacturers have attempted to increase the flow laminarity, decrease the exhaust speed and develop acoustic liners for selected duct areas. Retrofits are, however, not usually cost effective due to increased operational costs, e.g., fuel consumption can increase after engine modification because of increased weight. Finally, an attempt is made to assess, monetarily, the costs of noise pollution, wherein fines are levied for noisy aircraft and the money is spent insulating homes from noise.

The Distribution and Environmental Impacts of Noise Pollution Sadouqi Martyr Yazd International Airport Using GIS

Directory of Open Access Journals (Sweden)

H Zarei Mahmoud Abadi

2016-03-01

Full Text Available Introduction: Persecutors of aircraft noise at an airport has a close relationship with the alternate of landing and take-off weight of the aircraft and operations planning during the night. Now aircraft that spill in Yazd airport and take-off of aircraft is of jet engines or so-turbofan mean that the resulting sound will be very high. Methods: In this descriptive, cross-sectional  measurement of noise from aircraft traffic noise measuring station 7,The completed questionnaires to assess the effects of noise pollution in Yazd International Airport and the surrounding noise sensitive areas in 2014 by a portable audio device measurement is done. Results: The most amount of noise caused by aircraft traffic in the airport area and in adjacent areas with average noise level 84.8 dB at station No. 5 Regional Airport, located south of the airport, with an average noise level which was 75.5 dB. The results of analysis of questionnaires showed that 75 percent of people living in residential areas around the airport are being harassed by aircraft noise. Results indicate that, sleep disorders, nervousness, stress and mental illness and interfere with speech, regardless of the priority of different factors in the study area, are of the highest impact of aircraft noise. Conclusion: Aircraft noise is the strongest negative environmental factors that affect employees and residents around Yazd International Airport and can be harmful to health. The noise for health personnel, particularly those of daily tasks, are daily exposed to aircraft intense noise , are highly undesirable. So, essentially preventive severe conditions such as mandatory use of protective devices and soundproof acoustic shortening service personnel are needed for these people.

14 CFR 36.801 - Noise measurement.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Noise measurement. 36.801 Section 36.801 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Helicopters § 36.801 Noise measurement. For primary, normal...

Assessment of noise in the airplane cabin environment.

Science.gov (United States)

Zevitas, Christopher D; Spengler, John D; Jones, Byron; McNeely, Eileen; Coull, Brent; Cao, Xiaodong; Loo, Sin Ming; Hard, Anna-Kate; Allen, Joseph G

2018-03-15

To measure sound levels in the aircraft cabin during different phases of flight. Sound level was measured on 200 flights, representing six aircraft groups using continuous monitors. A linear mixed-effects model with random intercept was used to test for significant differences in mean sound level by aircraft model and across each flight phase as well as by flight phase, airplane type, measurement location and proximity to engine noise. Mean sound levels across all flight phases and aircraft groups ranged from 37.6 to >110 dB(A) with a median of 83.5 dB(A). Significant differences in noise levels were also observed based on proximity to the engines and between aircraft with fuselage- and wing mounted engines. Nine flights (4.5%) exceeded the recommended 8-h TWA exposure limit of 85 dB(A) by the NIOSH and ACGIH approach, three flights (1.5%) exceeded the 8-h TWA action level of 85 dB(A) by the OSHA approach, and none of the flights exceeded the 8-h TWA action level of 90 dB(A) by the OSHA PEL approach. Additional characterization studies, including personal noise dosimetry, are necessary to document accurate occupational exposures in the aircraft cabin environment and identify appropriate response actions. FAA should consider applying the more health-protective NIOSH/ACGIH occupational noise recommendations to the aircraft cabin environment.

Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

Science.gov (United States)

Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

1996-01-01

An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

Autonomous Slat-Cove-Filler Device for Reduction of Aeroacoustic Noise Associated with Aircraft Systems

Science.gov (United States)

Turner, Travis L. (Inventor); Kidd, Reggie T. (Inventor); Lockard, David P (Inventor); Khorrami, Mehdi R. (Inventor); Streett, Craig L. (Inventor); Weber, Douglas Leo (Inventor)

2016-01-01

A slat cove filler is utilized to reduce airframe noise resulting from deployment of a leading edge slat of an aircraft wing. The slat cove filler is preferably made of a super elastic shape memory alloy, and the slat cove filler shifts between stowed and deployed shapes as the slat is deployed. The slat cove filler may be configured such that a separate powered actuator is not required to change the shape of the slat cove filler from its deployed shape to its stowed shape and vice-versa. The outer contour of the slat cove filler preferably follows a profile designed to maintain accelerating flow in the gap between the slat cove filler and wing leading edge to provide for noise reduction.

The associations between noise sensitivity, reported physical and mental health, perceived environmental quality, and noise annoyance

Directory of Open Access Journals (Sweden)

Dirk Schreckenberg

2010-01-01

Full Text Available One hundred and ninety residents around Frankfurt Airport (46% female; 17-80 years were interviewed concerning noise annoyance due to transportation noise (aircraft, road traffic, perceived mental and physical health, perceived environmental quality, and noise sensitivity. The aim of the analyses was to test whether noise sensitivity reflects partly general environmental sensitivity and is associated with an elevated susceptibility for the perception of mental and physical health. In this study, the reported physical and mental health variables were not associated with noise exposure but with noise annoyance, and were interpreted to reflect nonspecific codeterminants of annoyance rather than noise effects. Noise sensitivity was found to influence total noise annoyance and aircraft noise annoyance but to a lesser degree annoyance due to road traffic noise. Noise sensitivity was associated with reported physical health, but not with reported mental health. Noise-sensitive persons reported poorer environmental quality in their residential area than less sensitive persons in particular with regard to air traffic (including the facets noise, pollution, and contaminations and quietness. Other aspects of the perceived quality of the environment were scarcely associated with noise sensitivity. This indicates that noise sensitivity is more specific and a reliable predictor of responses to noise from the dominant source (in this case air traffic rather than a predictor of the individual perception of the environmental quality in general.

The prediction of noise and installation effects of high-subsonic dual-stream jets in flight

Science.gov (United States)

Saxena, Swati

Both military and civil aircraft in service generate high levels of noise. One of the major contributors to this noise generated from the aircraft is the jet engine exhaust. This makes the study of jet noise and methods to reduce jet noise an active research area with the aim of designing quieter military and commercial aircraft. The current stringent aircraft noise regulations imposed by the Federal Aviation Administration (FAA) and other international agencies, have further raised the need to perform accurate jet noise calculations for more reliable estimation of the jet noise sources. The main aim of the present research is to perform jet noise simulations of single and dual-stream jets with engineering accuracy and assess forward flight effects on the jet noise. Installation effects such as caused by the pylon are also studied using a simplified pylon nozzle configuration. Due to advances in computational power, it has become possible to perform turbulent flow simulations of high speed jets, which leads to more accurate noise predictions. In the present research, a hybrid unsteady RANS-LES parallel multi-block structured grid solver called EAGLEJet is written to perform the nozzle flow calculations. The far-field noise calculation is performed using solutions to the Ffowcs Williams and Hawkings equation. The present calculations use meshes with 5 to 11 million grid points and require about three weeks of computing time with about 100 processors. A baseline single stream convergent nozzle and a dual-stream coaxial convergent nozzle are used for the flow and noise analysis. Calculations for the convergent nozzle are performed at a high subsonic jet Mach number of Mj = 0.9, which is similar to the operating conditions for commercial aircraft engines. A parallel flow gives the flight effect, which is simulated with a co-flow Mach number, Mcf varying from 0.0 to 0.28. The grid resolution effects, statistical properties of the turbulence and the heated jet effects

Fan Noise for a Concept Commercial Supersonic Transport

Science.gov (United States)

Stephens, David

2017-01-01

NASA is currently studying a commercial supersonic transport (CST) aircraft that could carry 35+ passengers at Mach 1.6+ with a 4000+nm range. The aircraft should also meet environmental goals for sonic boom, airport noise and emissions at cruise. With respect to airport noise, considerable effort has been put into predicting the noise due to the jet exhaust. This report describes an internal NASA effort to consider the contribution of fan noise to the overall engine noise of this class of aircraft.

Noise Effects on Health in the Context of Air Pollution Exposure.

Science.gov (United States)

Stansfeld, Stephen A

2015-10-14

For public health policy and planning it is important to understand the relative contribution of environmental noise on health compared to other environmental stressors. Air pollution is the primary environmental stressor in relation to cardiovascular morbidity and mortality. This paper reports a narrative review of studies in which the associations of both environmental noise and air pollution with health have been examined. Studies of hypertension, myocardial infarction, stroke, mortality and cognitive outcomes were included. Results suggest independent effects of environmental noise from road traffic, aircraft and, with fewer studies, railway noise on cardiovascular outcomes after adjustment for air pollution. Comparative burden of disease studies demonstrate that air pollution is the primary environmental cause of disability adjusted life years lost (DALYs). Environmental noise is ranked second in terms of DALYs in Europe and the DALYs attributed to noise were more than those attributed to lead, ozone and dioxins. In conclusion, in planning and health impact assessment environmental noise should be considered an independent contributor to health risk which has a separate and substantial role in ill-health separate to that of air pollution.

Effects of external boundary layer flow on jet noise in flight

Science.gov (United States)

Sarohia, V.; Massier, P. F.

1976-01-01

The effects on jet flow of the external boundary layer flow emanating from the trailing edge of an engine cowl in flight has been shown to be the main reason for the disparity between predicted and experimental results obtained from flight measurements. Flight simulation experiments indicate that the external boundary layer flow tends to shield the jet flow in flight. This in turn modifies the jet noise source in flight and consequently the radiated noise from aircraft in flight. Close to 90 deg angle to the intake and in the forward quadrant, this study indicates that the far field jet noise and its spectrum scales approximately with the absolute jet velocity instead of the relative velocity as has been assumed in the existing prediction models.

Fuselage panel noise attenuation by piezoelectric switching control

International Nuclear Information System (INIS)

Makihara, Kanjuro; Onoda, Junjiro; Minesugi, Kenji; Miyakawa, Takeya

2010-01-01

This paper describes a problem that we encountered in our noise attenuation project and our solution for it. We intend to attenuate low-frequency noise that transmits through aircraft fuselage panels. Our method of noise attenuation is implemented with a piezoelectric semi-active system having a selective switch instead of an active energy-supply system. The semi-active controller is based on the predicted sound pressure distribution obtained from acoustic emission analysis. Experiments and numerical simulations demonstrate that the semi-active method attenuates acoustic levels of not only the simple monochromatic noise but also of broadband noise. We reveal that tuning the electrical parameters in the circuit is the key to effective noise attenuation, to overcome the acoustic excitation problem due to sharp switching actions, as well as to control chattering problems. The results obtained from this investigation provide meaningful insights into designing noise attenuation systems for comfortable aircraft cabin environments

A review of the literature related to potential health effects of aircraft noise.

Science.gov (United States)

2010-07-01

Previous reports have dealt with the health effects of noise in some capacity. Many of these have : considered various quality of life factors as the primary health effects. This is in line with the World Health : Organization (WHO, 1946) defin...

Aviation Noise Impacts: State of the Science

NARCIS (Netherlands)

Basner, M.; Clark, C.; Hansell, A.; Hileman, J.; Janssen, S.; Shepherd, K.; Sparrow, V.

2017-01-01

Noise is defined as 'unwanted sound.' Aircraft noise is one, if not the most detrimental environmental effect of aviation. It can cause community annoyance, disrupt sleep, adversely affect academic performance of children, and could increase the risk for cardiovascular disease of people living in

Analytical modeling of the structureborne noise path on a small twin-engine aircraft

Science.gov (United States)

Cole, J. E., III; Stokes, A. Westagard; Garrelick, J. M.; Martini, K. F.

1988-01-01

The structureborne noise path of a six passenger twin-engine aircraft is analyzed. Models of the wing and fuselage structures as well as the interior acoustic space of the cabin are developed and used to evaluate sensitivity to structural and acoustic parameters. Different modeling approaches are used to examine aspects of the structureborne path. These approaches are guided by a number of considerations including the geometry of the structures, the frequency range of interest, and the tractability of the computations. Results of these approaches are compared with experimental data.

Does Traffic-related Air Pollution Explain Associations of Aircraft and Road Traffic Noise Exposure on Children's Health and Cognition? A Secondary Analysis of the United Kingdom Sample From the RANCH Project

Science.gov (United States)

Clark, Charlotte; Crombie, Rosanna; Head, Jenny; van Kamp, Irene; van Kempen, Elise; Stansfeld, Stephen A.

2012-01-01

The authors examined whether air pollution at school (nitrogen dioxide) is associated with poorer child cognition and health and whether adjustment for air pollution explains or moderates previously observed associations between aircraft and road traffic noise at school and children's cognition in the 2001–2003 Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) project. This secondary analysis of a subsample of the United Kingdom RANCH sample examined 719 children who were 9–10 years of age from 22 schools around London's Heathrow airport for whom air pollution data were available. Data were analyzed using multilevel modeling. Air pollution exposure levels at school were moderate, were not associated with a range of cognitive and health outcomes, and did not account for or moderate associations between noise exposure and cognition. Aircraft noise exposure at school was significantly associated with poorer recognition memory and conceptual recall memory after adjustment for nitrogen dioxide levels. Aircraft noise exposure was also associated with poorer reading comprehension and information recall memory after adjustment for nitrogen dioxide levels. Road traffic noise was not associated with cognition or health before or after adjustment for air pollution. Moderate levels of air pollution do not appear to confound associations of noise on cognition and health, but further studies of higher air pollution levels are needed. PMID:22842719

Does traffic-related air pollution explain associations of aircraft and road traffic noise exposure on children's health and cognition? A secondary analysis of the United Kingdom sample from the RANCH project.

Science.gov (United States)

Clark, Charlotte; Crombie, Rosanna; Head, Jenny; van Kamp, Irene; van Kempen, Elise; Stansfeld, Stephen A

2012-08-15

The authors examined whether air pollution at school (nitrogen dioxide) is associated with poorer child cognition and health and whether adjustment for air pollution explains or moderates previously observed associations between aircraft and road traffic noise at school and children's cognition in the 2001-2003 Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) project. This secondary analysis of a subsample of the United Kingdom RANCH sample examined 719 children who were 9-10 years of age from 22 schools around London's Heathrow airport for whom air pollution data were available. Data were analyzed using multilevel modeling. Air pollution exposure levels at school were moderate, were not associated with a range of cognitive and health outcomes, and did not account for or moderate associations between noise exposure and cognition. Aircraft noise exposure at school was significantly associated with poorer recognition memory and conceptual recall memory after adjustment for nitrogen dioxide levels. Aircraft noise exposure was also associated with poorer reading comprehension and information recall memory after adjustment for nitrogen dioxide levels. Road traffic noise was not associated with cognition or health before or after adjustment for air pollution. Moderate levels of air pollution do not appear to confound associations of noise on cognition and health, but further studies of higher air pollution levels are needed.

Introductory guide to noise

CSIR Research Space (South Africa)

Ferreira, T.M

1973-01-01

Full Text Available or (by remaining at the 'alarm' level) prevents us from sleeping or resting. Some noise comes into buildings from outside, such as when a passing jet plane drowns a telephone conversation or when traffic noise prevents one from hearing an interesting... on aircraft that make too much noise. Motor cars, buses, buzz-bikes and vacuum deaners can be effectively quietened but until now the public has not been prepared to pay the price of legislation. Also, many young sports-car enthusiasts still think...

Small Engine Technology (SET) Task 24 Business and Regional Aircraft System Studies

Science.gov (United States)

Lieber, Lysbeth

2003-01-01

This final report has been prepared by Honeywell Engines & Systems, Phoenix, Arizona, a unit of Honeywell International Inc., documenting work performed during the period June 1999 through December 1999 for the National Aeronautics and Space Administration (NASA) Glenn Research Center, Cleveland, Ohio, under the Small Engine Technology (SET) Program, Contract No. NAS3-27483, Task Order 24, Business and Regional Aircraft System Studies. The work performed under SET Task 24 consisted of evaluating the noise reduction benefits compared to the baseline noise levels of representative 1992 technology aircraft, obtained by applying different combinations of noise reduction technologies to five business and regional aircraft configurations. This report focuses on the selection of the aircraft configurations and noise reduction technologies, the prediction of noise levels for those aircraft, and the comparison of the noise levels with those of the baseline aircraft.

AIRPORT NOISE CHARGES AND LOCAL COMMUNITIES: APPLICATION TO REGIONAL AIRPORTS

Directory of Open Access Journals (Sweden)

LUCA MANTECCHINI

2016-11-01

Full Text Available There have always been conflicts among airports and local communities due to the aeronautical noise generated by airport operations. In fact, this is a factor that - if not properly managed - could severely cut down the growth of air traffic in an airport with direct effects on the economic and territorial system. Beside this, in the last decade the critical issues related to the impact of aeronautical noise on airport operations have greatly reduced, thanks to technological improvements in aircraft design. Nevertheless, the reduction of noise emissions during a single aircraft operation does not make the issue of the airports’ location less important. This is the case of regional airports in EU, which have recently experimented a large traffic increase due to the development of low-cost traffic. It is now clear that the problem cannot be reduced to its mere technological aspect, but it ought to be dealt with the involvement of the various stakeholders in order to mitigate the emissions and adequately compensate the impacts to local communities. Typically, there are two possible countermeasures to mitigate the effects of aircraft noise: operational measures, based on the application of technological and organizational devices and market-based measures. The application of noise taxes, aiming at compensating the negative externalities generated by airport operations is becoming increasingly widespread in EU. In this paper, a methodology for the application of noise taxes based on the actual noise of aircraft operating into an airport is discussed and implemented in a test case.

Noise sensitivity and reactions to noise and other environmental conditions

NARCIS (Netherlands)

Miedema, H.M.E.; Vos, H.

2003-01-01

This article integrates findings from the literature and new results regarding noise sensitivity. The new results are based on analyses of 28 combined datasets (N=23 038), and separate analyses of a large aircraft noise study (N=10939). Three topics regarding noise sensitivity are discussed, namely,

Noise Effects on Health in the Context of Air Pollution Exposure

Science.gov (United States)

Stansfeld, Stephen A.

2015-01-01

For public health policy and planning it is important to understand the relative contribution of environmental noise on health compared to other environmental stressors. Air pollution is the primary environmental stressor in relation to cardiovascular morbidity and mortality. This paper reports a narrative review of studies in which the associations of both environmental noise and air pollution with health have been examined. Studies of hypertension, myocardial infarction, stroke, mortality and cognitive outcomes were included. Results suggest independent effects of environmental noise from road traffic, aircraft and, with fewer studies, railway noise on cardiovascular outcomes after adjustment for air pollution. Comparative burden of disease studies demonstrate that air pollution is the primary environmental cause of disability adjusted life years lost (DALYs). Environmental noise is ranked second in terms of DALYs in Europe and the DALYs attributed to noise were more than those attributed to lead, ozone and dioxins. In conclusion, in planning and health impact assessment environmental noise should be considered an independent contributor to health risk which has a separate and substantial role in ill-health separate to that of air pollution. PMID:26473905

A preliminary study of the effects of aircraft noise on families who ...

African Journals Online (AJOL)

Background: The use of air transportation has grown in the last century, escalating the noise exposure of families residing in close proximity to airports. The audiological effects need to be assessed to determine the impact of this increase on children and young adults living near to airports in South Africa. Method: Hearing ...

Noise pollution in Lahore and the solution

International Nuclear Information System (INIS)

Ahmad, K.

1999-01-01

The main objective of the study is to know the current status of noise levels in Lahore as compared to NEQS . Sound Level Meter model 211 FS Quest Electronics with a 50-120 dBA selectable range was used in the current investigation. Study relates to road traffic noise, aircraft noise at city airports, rail traffic noise, noise levels in urban centers and occupational noise. Investigation revealed that nine main commercial centers, six public hospital and ten educational institution of Lahore had values higher than NEQS (85 dBA). Maximum noise producing vehicles on Lahore roads are scooter producing a noise of 90, 86 and 87 dBA. There are forty airports in operation in the country and the aircraft being used has higher noise level varying from 16 to 120 dBA. Based on age and length of service permanent hearing damage has been observed in skilled industrial workers. Risk from hearing damage of industrial workers can be reduced by the use of some form of ear protection. Ear plugs can reduce noise levels by 15 to 35 dBA according to their design and fit. Industrial noise from heavy machinery can be reduced by anti-vibration mountings. Noisy work area in industry should be either isolated or surrounded by baffles. The most appealing approach to reduce noise problems in communities due to aircraft operation is reduction of the noise generated by the aircraft and land use planning. (author)

Aircraft noise: accounting for changes in air traffic with time of day.

Science.gov (United States)

Schäffer, Beat; Bütikofer, Rudolf; Plüss, Stefan; Thomann, Georg

2011-01-01

Aircraft noise contours are estimated using model calculations and, due to their impact on land use planning, they need to be highly accurate. During night time, not only the number and dominant types of aircraft may differ from daytime but also the flight paths flown may differ. To determine to which detail these variations in flight paths need to be considered, calculations were performed exemplarily for two airports using all available radar data over 1 year, taking into account their changes over the day. The results of this approach were compared with results of a simpler approach which does not consider such changes. While both calculations yielded similar results for the day and close to the airport, differences increased with distance as well as with the period of day (day

analysis of the environmental and socio-economic impact of noise

African Journals Online (AJOL)

Dr Obe

Interest in noise control studies is only recent in Nigeria. ... standards for environmental pollution by the Federal ... heaters, gas flare system, reactors, water injection plants, pumps ..... review of health effects of aircraft noise. Aust. NZ J. Public ...

Optimizing an Actuator Array for the Control of Multi-Frequency Noise in Aircraft Interiors

Science.gov (United States)

Palumbo, D. L.; Padula, S. L.

1997-01-01

Techniques developed for selecting an optimized actuator array for interior noise reduction at a single frequency are extended to the multi-frequency case. Transfer functions for 64 actuators were obtained at 5 frequencies from ground testing the rear section of a fully trimmed DC-9 fuselage. A single loudspeaker facing the left side of the aircraft was the primary source. A combinatorial search procedure (tabu search) was employed to find optimum actuator subsets of from 2 to 16 actuators. Noise reduction predictions derived from the transfer functions were used as a basis for evaluating actuator subsets during optimization. Results indicate that it is necessary to constrain actuator forces during optimization. Unconstrained optimizations selected actuators which require unrealistically large forces. Two methods of constraint are evaluated. It is shown that a fast, but approximate, method yields results equivalent to an accurate, but computationally expensive, method.

Acoustic Characterization of a Multi-Rotor Unmanned Aircraft

Science.gov (United States)

Feight, Jordan; Gaeta, Richard; Jacob, Jamey

2017-11-01

In this study, the noise produced by a small multi-rotor rotary wing aircraft, or drone, is measured and characterized. The aircraft is tested in different configurations and environments to investigate specific parameters and how they affect the acoustic signature of the system. The parameters include rotor RPM, the number of rotors, distance and angle of microphone array from the noise source, and the ambient environment. The testing environments include an anechoic chamber for an idealized setting and both indoor and outdoor settings to represent real world conditions. PIV measurements are conducted to link the downwash and vortical flow structures from the rotors with the noise generation. The significant factors that arise from this study are the operational state of the aircraft and the microphone location (or the directivity of the noise source). The directivity in the rotor plane was shown to be omni-directional, regardless of the varying parameters. The tonal noise dominates the low to mid frequencies while the broadband noise dominates the higher frequencies. The fundamental characteristics of the acoustic signature appear to be invariant to the number of rotors. Flight maneuvers of the aircraft also significantly impact the tonal content in the acoustic signature.

A study of the effect of flight density and background noise on V/STOL acceptability. [effective perceived noise level as measure of annoyance

Science.gov (United States)

Sternfeld, H., Jr.; Hinterkeuser, E. G.; Hackman, R. B.; Davis, J.

1974-01-01

A study was conducted in which test subjects evaluated the sounds of a helicopter, a turbofan STOL and a turbojet airplane while engaged in work and leisure activities. Exposure to a high repetitive density of the aircraft sounds did not make the individual sounds more annoying but did create an unacceptable environment. The application of a time duration term to db(A) resulted in a measure which compared favorably with EPNL as a predictor of annoyance. Temporal variations in background noise level had no significant effect on the rated annoyance.

Jet Noise Shielding Provided by a Hybrid Wing Body Aircraft

Science.gov (United States)

Doty, Michael J.; Brooks, Thomas F.; Burley, Casey L.; Bahr, Christopher J.; Pope, Dennis S.

2014-01-01

One approach toward achieving NASA's aggressive N+2 noise goal of 42 EPNdB cumulative margin below Stage 4 is through the use of novel vehicle configurations like the Hybrid Wing Body (HWB). Jet noise measurements from an HWB acoustic test in NASA Langley's 14- by 22-Foot Subsonic Tunnel are described. Two dual-stream, heated Compact Jet Engine Simulator (CJES) units are mounted underneath the inverted HWB model on a traversable support to permit measurement of varying levels of shielding provided by the fuselage. Both an axisymmetric and low noise chevron nozzle set are investigated in the context of shielding. The unshielded chevron nozzle set shows 1 to 2 dB of source noise reduction (relative to the unshielded axisymmetric nozzle set) with some penalties at higher frequencies. Shielding of the axisymmetric nozzles shows up to 6.5 dB of reduction at high frequency. The combination of shielding and low noise chevrons shows benefits beyond the expected additive benefits of the two, up to 10 dB, due to the effective migration of the jet source peak noise location upstream for increased shielding effectiveness. Jet noise source maps from phased array results processed with the Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) algorithm reinforce these observations.

Cross-stream ejection in the inter-wheel region of aircraft landing gears

Science.gov (United States)

McCarthy, Philip; Ekmekci, Alis

2014-11-01

The reduction of aircraft noise is an important challenge currently faced by aircraft manufacturers. During approach and landing, the landing gears contribute a significant proportion of the aircraft generated noise. It is therefore critical that the key noise sources be identified and understood in order for effective mitigation methods to be developed. For a simplified two-wheel nose landing gear, a strong cross stream flow ejection phenomena has been observed to occur in the inter-wheel region in presence of wheel wells. The location and orientation of these flow ejections causes highly unsteady, three dimensional flow between the wheels that may impinge on other landing gear components, thereby potentially acting as a significant noise generator. The effects of changing the inter-wheel geometry (inter-wheel spacing, the wheel well depth and main strut geometry) upon the cross-stream ejection behaviour has been experimentally investigated using both qualitative flow visualisation and quantitative PIV techniques. A summary of the key results will be presented for the three main geometrical parameters under examination and the application of these findings to real life landing gears will be discussed. Thanks to Messier-Bugatti-Dowty and NSERC for their support for this project.

Ground noise measurements during static and flyby operations of the Cessna 02-T turbine powered airplane

Science.gov (United States)

Hilton, D. A.; Henderson, H. R.; Lawton, B. W.

1975-01-01

The field noise measurements on the Cessna 02-T turbine powered propeller aircraft are presented. The objective of the study was to obtain the basic noise characteristics of the aircraft during static ground runs and flyover tests, to identify the sources of the noise, and to correlate the noises with the aircraft operating conditions. The results are presented in the form of a overall noise levels, radiation patterns, and frequency spectra. The noise characteristics of the turbine powered aircraft are compared with those of the reciprocating engine powered aircraft.

NASA Jet Noise Research

Science.gov (United States)

Henderson, Brenda

2016-01-01

The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.

Flap Side Edge Liners for Airframe Noise Reduction

Science.gov (United States)

Jones, Michael G. (Inventor); Khorrami, Mehdi R. (Inventor); Choudhari, Meelan M. (Inventor); Howerton, Brian M. (Inventor)

2014-01-01

One or more acoustic liners comprising internal chambers or passageways that absorb energy from a noise source on the aircraft are disclosed. The acoustic liners may be positioned at the ends of flaps of an aircraft wing to provide broadband noise absorption and/or dampen the noise producing unsteady flow features, and to reduce the amount of noise generated due to unsteady flow at the inboard and/or outboard end edges of a flap.

Sleep disturbance due to noise: Current issues and future research

Directory of Open Access Journals (Sweden)

Ken Hume

2010-01-01

Full Text Available There is growing interest in carrying out further research to understand and reduce the impact of aircraft noise on airport neighborhood in anticipation of the projected substantial increase in global aviation. Soundscapes provide new analytical methods and a broader, more comprehensive appreciation of the aural environment, which may have a useful role in understanding noise-induced sleep disturbance and annoyance. Current noise metrics like Leq do not provide a common language to report noise environment to residents, which is a key obstacle to effective noise management and acceptance. Non-auditory effects complicate the production of consistent dose-response functions for aircraft noise affecting sleep and annoyance. There are various end-points that can be chosen to assess the degree of sleep disturbance, which has detracted from the clarity of results that has been communicated to wider audiences. The World Health Organization (WHO-Europe has produced Night Noise Guidelines for Europe, which act as a clear guide for airports and planners to work towards. Methodological inadequacies and the need for simpler techniques to record sleep will be considered with the exciting potential to greatly increase cost-effective field data acquisition, which is needed for large scale epidemiological studies

Comprehensive analysis of transport aircraft flight performance

Science.gov (United States)

Filippone, Antonio

2008-04-01

This paper reviews the state-of-the art in comprehensive performance codes for fixed-wing aircraft. The importance of system analysis in flight performance is discussed. The paper highlights the role of aerodynamics, propulsion, flight mechanics, aeroacoustics, flight operation, numerical optimisation, stochastic methods and numerical analysis. The latter discipline is used to investigate the sensitivities of the sub-systems to uncertainties in critical state parameters or functional parameters. The paper discusses critically the data used for performance analysis, and the areas where progress is required. Comprehensive analysis codes can be used for mission fuel planning, envelope exploration, competition analysis, a wide variety of environmental studies, marketing analysis, aircraft certification and conceptual aircraft design. A comprehensive program that uses the multi-disciplinary approach for transport aircraft is presented. The model includes a geometry deck, a separate engine input deck with the main parameters, a database of engine performance from an independent simulation, and an operational deck. The comprehensive code has modules for deriving the geometry from bitmap files, an aerodynamics model for all flight conditions, a flight mechanics model for flight envelopes and mission analysis, an aircraft noise model and engine emissions. The model is validated at different levels. Validation of the aerodynamic model is done against the scale models DLR-F4 and F6. A general model analysis and flight envelope exploration are shown for the Boeing B-777-300 with GE-90 turbofan engines with intermediate passenger capacity (394 passengers in 2 classes). Validation of the flight model is done by sensitivity analysis on the wetted area (or profile drag), on the specific air range, the brake-release gross weight and the aircraft noise. A variety of results is shown, including specific air range charts, take-off weight-altitude charts, payload-range performance

The Shadow Price of Aircraft Noise Nuisance

OpenAIRE

Bernard M.S. van Praag; B.E. Baarsma

2000-01-01

This paper has a twofold objective. First, we develop a new method toassess the monetary value for individuals of external effects (viz., aircraftnoise nuisance) which are not or only partly internalized in market prices. The method makes use of an ordinal index of life satisfaction as scored by individual respondents who are subjected in varying intensity to the external effect. Our second objective is to assess, with this method, to what extent noise nuisance effects around Amsterdam Airpor...

Propulsion Noise Reduction Research in the NASA Advanced Air Transport Technology Project

Science.gov (United States)

Van Zante, Dale; Nark, Douglas; Fernandez, Hamilton

2017-01-01

The Aircraft Noise Reduction (ANR) sub-project is focused on the generation, development, and testing of component noise reduction technologies progressing toward the NASA far term noise goals while providing associated near and mid-term benefits. The ANR sub-project has efforts in airframe noise reduction, propulsion (including fan and core) noise reduction, acoustic liner technology, and propulsion airframe aeroacoustics for candidate conventional and unconventional aircraft configurations. The current suite of propulsion specific noise research areas is reviewed along with emerging facility and measurement capabilities. In the longer term, the changes in engine and aircraft configuration will influence the suite of technologies necessary to reduce noise in next generation systems.

The influence of acoustical and non-acoustical factors on short-term annoyance due to aircraft noise in the field - The COSMA study.

Science.gov (United States)

Bartels, Susanne; Márki, Ferenc; Müller, Uwe

2015-12-15

Air traffic has increased for the past decades and is forecasted to continue to grow. Noise due to current airport operations can impair the physical and psychological well-being of airport residents. The field study investigated aircraft noise-induced short-term (i.e., within hourly intervals) annoyance in local residents near a busy airport. We aimed at examining the contribution of acoustical and non-acoustical factors to the annoyance rating. Across four days from getting up till going to bed, 55 residents near Cologne/Bonn Airport (M=46years, SD=14years, 34 female) rated their annoyance due to aircraft noise at hourly intervals. For each participant and each hour, 26 noise metrics from outdoor measurements and further 6 individualized metrics that took into account the sound attenuation due to each person's whereabouts in and around their homes were obtained. Non-acoustical variables were differentiated into situational factors (time of day, performed activity during past hour, day of the week) and personal factors (e.g., sensitivity to noise, attitudes, domestic noise insulation). Generalized Estimation Equations were applied for the development of a prediction model for annoyance. Acoustical factors explained only a small proportion (13.7%) of the variance in the annoyance ratings. The number of fly-overs predicted annoyance better than did equivalent and maximum sound pressure levels. The proportion of explained variance in annoyance rose considerably (to 27.6%) when individualized noise metrics as well as situational and personal variables were included in the prediction model. Consideration of noise metrics related to the number of fly-overs and individual adjustment of noise metrics can improve the prediction of short-term annoyance compared to models using equivalent outdoor levels only. Non-acoustical factors have remarkable impact not only on long-term annoyance as shown before but also on short-term annoyance judged in the home environment. Copyright

Full-Scale Turbofan Engine Noise-Source Separation Using a Four-Signal Method

Science.gov (United States)

Hultgren, Lennart S.; Arechiga, Rene O.

2016-01-01

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and expected advances in mitigation of other noise sources. During on-ground, static-engine acoustic tests, combustor noise is generally sub-dominant to other engine noise sources because of the absence of in-flight effects. Consequently, noise-source separation techniques are needed to extract combustor-noise information from the total noise signature in order to further progress. A novel four-signal source-separation method is applied to data from a static, full-scale engine test and compared to previous methods. The new method is, in a sense, a combination of two- and three-signal techniques and represents an attempt to alleviate some of the weaknesses of each of those approaches. This work is supported by the NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project, Aircraft Noise Reduction Subproject and the NASA Glenn Faculty Fellowship Program.

Environmental noise exposure, early biological risk and mental health in nine to ten year old children: a cross-sectional field study

Directory of Open Access Journals (Sweden)

Stansfeld Stephen A

2011-05-01

Full Text Available Abstract Background Previous research suggests that children born prematurely or with a low birth weight are more vulnerable to the mental health effects of ambient neighbourhood noise; predominantly road and rail noise, at home. This study used data from the Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH study to see if this finding extends to aircraft and road traffic noise at school. Methods Children and their parents from schools around three European airports were selected to represent a range of aircraft and road traffic noise exposure levels. Birth weight and gestation period were merged to create a dichotomous variable assessing 'early biological risk'. Mental health was assessed using the Strengths and Difficulties Questionnaire (SDQ. Complete data were available for 1900 primary school children. Results Children who were 'at risk' (i.e. low birth weight or premature birth were rated as having more conduct problems and emotional symptoms and poorer overall mental health than children not at risk. However, there was no interaction between aircraft or road traffic noise exposure at school and early biological risk. Conclusions Data from the RANCH study suggests that children with early biological risk are not more vulnerable to the effects of aircraft or road traffic noise at school on mental health than children without this risk; however they are more likely to have mental ill-health.

Study of quiet turbofan STOL aircraft for short haul transportation

Science.gov (United States)

Higgins, T. P.; Stout, E. G.; Sweet, H. S.

1973-01-01

Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. In these studies, the total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

Application of acoustically tuned resonators for the improvement of sound insulation in aircraft.

NARCIS (Netherlands)

Hannink, M.H.C.; Vlasma, J.P.; Wijnant, Ysbrand H.; de Boer, Andries

2005-01-01

One of the aims of the EU project FACE (Friendly Aircraft Cabin Environment) is to reduce aircraft interior noise. For modern aircraft flying at cruise conditions, the turbulent boundary layer is the main source for cabin noise. Normally, the turbulent boundary layer causes the trim panels to

DART Core/Combustor-Noise Initial Test Results

Science.gov (United States)

Boyle, Devin K.; Henderson, Brenda S.; Hultgren, Lennart S.

2017-01-01

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aero0propulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This presentation gives a brief description of the recently completed DART core combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data was simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant far field, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. An initial assessment shows that the data is of high quality and compares well with results from a quick 2014 feasibility test. Combustor noise components of measured total-noise signatures were educed using a two-signal source-separation method an dare found to occur in the expected frequency range. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Application of powered lift and mechanical flap concepts for civil short-haul transport aircraft design

Science.gov (United States)

Conlon, J. A.; Bowles, J. V.

1977-01-01

The objective of this paper is to determine various design and performance parameters, including wing loading and thrust loading requirements, for powered-lift and mechanical flap conceptual aircraft constrained by field length and community noise impact. Mission block fuel and direct operating costs (DOC) were found for optimum designs. As a baseline, the design and performance parameters were determined for the aircraft using engines without noise suppression. The constraint of the 90 EPNL noise contour being less than 2.6 sq km (1.0 sq mi) in area was then imposed. The results indicate that for both aircraft concepts the design gross weight, DOC, and required mission block fuel decreased with field length. At field lengths less than 1100 m (3600 ft) the powered lift aircraft had lower DOC and block fuel than the mechanical flap aircraft but produced higher unsuppressed noise levels. The noise goal could easily be achieved with nacelle wall treatment only and thus resulted in little or no performance or weight penalty for all studied aircraft.

The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

Science.gov (United States)

Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

2013-01-01

The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

OPERATIONAL RESTRICTIONS FOR REDUCING NOISE AND THE SAFETY OF AIR OPERATIONS

Directory of Open Access Journals (Sweden)

Anna KWASIBORSKA

2017-03-01

Full Text Available Many European airports are located in close proximity to residential or protected areas. Aircraft noise emissions caused by the landing and taking off of aircraft are a big problem in these areas. From an operational point of view, the method for reducing noise is to reduce traffic volume or change its organization, especially during the night. Some procedures and tools have been developed to support air traffic management in the implementation of operational constraints necessary to maintain noise at an acceptable level. The objective of this paper is to analyse the effectiveness of these tools. For this purpose, we have analysed existing methods of operational noise reduction, taking into account their influence on the structure, smoothness, punctuality and, especially, the safety of air traffic. As a result, existing risks have been identified, while methods have been proposed to combine two important air traffic service tasks: ensuring safety, while taking into account the environmental constraints, especially in relation to the acoustic climate.

NoiseMap and AEDT Gap Analysis

Science.gov (United States)

2017-09-30

NoiseMap and the Aviation Environmental Design Tool (AEDT) both use an integrated modeling approach to calculate aircraft noise in and around an airfield. Both models also employ the same general overall approach by using airfield operational data, s...

Particulate Matter and Noise Impact Studies of Waste Rock Dump*

African Journals Online (AJOL)

Michael

2016-06-01

Jun 1, 2016 ... (vegetation) among other recommended strategies would control ambient noise ... respiratory system's natural defences and lodge ... Environmental noise monitoring was conducted ..... (1998), “Nocturnal Aircraft Noise and.

Examination of the low frequency limit for helicopter noise data in the Federal Aviation Administration's Aviation Environmental Design Tool and Integrated Noise Model

Science.gov (United States)

2010-04-19

The Federal Aviation Administration (FAA) aircraft noise modeling tools Aviation Environmental Design Tool (AEDTc) and Integrated Noise Model (INM) do not currently consider noise below 50 Hz in their computations. This paper describes a preliminary ...

Fault Detection of Aircraft Cable via Spread Spectrum Time Domain Reflectometry

Directory of Open Access Journals (Sweden)

Xudong SHI

2014-03-01

Full Text Available As the airplane cable fault detection based on TDR (time domain reflectometry is affected easily by various noise signals, which makes the reflected signal attenuate and distort heavily, failing to locate the fault. In order to solve these problems, a method of spread spectrum time domain reflectometry (SSTDR is introduced in this paper, taking the advantage of the sharp peak of correlation function. The test signal is generated from ML sequence (MLS modulated by sine wave in the same frequency. Theoretically, the test signal has the very high immunity of noise, which can be applied with excellent precision to fault location on the aircraft cable. In this paper, the method of SSTDR was normally simulated in MATLAB. Then, an experimental setup, based on LabVIEW, was organized to detect and locate the fault on the aircraft cable. It has been demonstrated that SSTDR has the high immunity of noise, reducing some detection errors effectively.

Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction - Challenges and Approaches to Hyperelastic Structural Modeling and Analysis

Science.gov (United States)

Sreekantamurthy, Thammaiah; Turner, Travis L.; Moore, James B.; Su, Ji

2014-01-01

Airframe noise is a significant part of the overall noise of transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) Project goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that connects the side edges of the deployable flap to the adjacent main-wing structure. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations and novel interface hardware. The resulting highly-deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating feasible concepts that met the design constraints. The focus of this paper is to describe the many challenges encountered with hyperelastic finite element modeling and the nonlinear structural analysis of evolving FLEXSEL concepts. Detailed herein is the nonlinear analysis of FLEXSEL concepts that emerged during the project which include solid-section, foamcore, hollow, extended-span and pre-stressed concepts. Coupon-level analysis performed on elastomeric interface joints, which form a part of the FLEXSEL topology development, are also presented.

Modeling and Prediction of Krueger Device Noise

Science.gov (United States)

Guo, Yueping; Burley, Casey L.; Thomas, Russell H.

2016-01-01

This paper presents the development of a noise prediction model for aircraft Krueger flap devices that are considered as alternatives to leading edge slotted slats. The prediction model decomposes the total Krueger noise into four components, generated by the unsteady flows, respectively, in the cove under the pressure side surface of the Krueger, in the gap between the Krueger trailing edge and the main wing, around the brackets supporting the Krueger device, and around the cavity on the lower side of the main wing. For each noise component, the modeling follows a physics-based approach that aims at capturing the dominant noise-generating features in the flow and developing correlations between the noise and the flow parameters that control the noise generation processes. The far field noise is modeled using each of the four noise component's respective spectral functions, far field directivities, Mach number dependencies, component amplitudes, and other parametric trends. Preliminary validations are carried out by using small scale experimental data, and two applications are discussed; one for conventional aircraft and the other for advanced configurations. The former focuses on the parametric trends of Krueger noise on design parameters, while the latter reveals its importance in relation to other airframe noise components.

Community reaction to noise from power stations

International Nuclear Information System (INIS)

Job, R.F.S.; Hede, A.J.

1989-01-01

Community reaction is a major consideration in noise control. The relationship between noise exposure and community reaction has received considerable attention in relation to railway, traffic, aircraft and impulsive noise. The results have shown a number of features in common, including: similarly shaped noise/reaction functions; similar results across different measurement techniques and cultures, noise/reaction correlations based on individual respondent data are low (mean r = 0.42 ± 0.12: Job, 1988), although correlations of .58 and above have been reported correlations based on data grouped by noise exposure are generally high and relatively unaffected by the type of noise studied whereas correlations based on individual data tend to be lower for impulsive noise than for transportation noise attitude to the noise source and sensitivity to noise shows strong correlations with reaction. This paper reports that the present study was undertaken in order toe establish over a wider range of noise exposure whether community reaction to power station noise is similar to reaction to other types of non-impulsive noise. It is possible that reaction is different given important differences in the source of the noise which may affect attitude. Attitudes towards power stations may be more positive than attitudes to aircraft or rail noise for example, because almost all respondents use electricity regularly every day. Further, the power stations in the present study provided employment for the relatively small surrounding communities

Proceedings of the Jet Noise Workshop

Science.gov (United States)

Huff, Dennis (Compiler)

2001-01-01

Jet noise has been a major problem for aircraft for nearly 50 years. There has been considerable research performed around the world aimed at identifying ways to reduce jet noise. This work was first intended for turbojet aircraft and later extended to low bypass ratio turbofans. Many of the people who performed this pioneering research have retired or are no longer active in aeroacoustics. After so many years of work in jet noise, it is a challenge to piece together the history of its development through existing publications due to the large volume of documents. It is possible to forget important developments from the past as new researchers tackle similar problems. Therefore, a jet noise workshop was organized by the AeroAcoustics Research Consortium (AARC) with the intent of reviewing research that has been done by experts throughout the world. The forum provided a unique opportunity for current researchers to hear the diverse views from world experts on issues related to jet noise modeling and interpretation of experimental data.

Analysis of a Stretched Derivative Aircraft with Open Rotor Propulsion

Science.gov (United States)

Berton, Jeffrey J.; Hendricks, Eric S.; Haller, William J.; Guynn, Mark D.

2015-01-01

Research into advanced, high-speed civil turboprops received significant attention during the 1970s and 1980s when fuel efficiency was the driving focus of U.S. aeronautical research. But when fuel prices declined sharply there was no longer sufficient motivation to continue maturing the technology. Recent volatility in fuel prices and increasing concern for aviation's environmental impact, however, have renewed interest in unducted, open rotor propulsion and revived research by NASA and a number of engine manufacturers. Recently, NASA and General Electric have teamed to conduct several investigations into the performance and noise of an advanced, single-aisle transport with open rotor propulsion. The results of these initial studies indicate open rotor engines have the potential to provide significant reduction in fuel consumption compared to aircraft using turbofan engines with equivalent core technology. In addition, noise analysis of the concept indicates that an open rotor aircraft in the single-aisle transport class would be able to meet current noise regulations with margin. The behavior of derivative open rotor transports is of interest. Heavier, "stretched" derivative aircraft tend to be noisier than their lighter relatives. Of particular importance to the business case for the concept is how the noise margin changes relative to regulatory limits within a family of similar open rotor aircraft. The subject of this report is a performance and noise assessment of a notional, heavier, stretched derivative airplane equipped with throttle-push variants of NASA's initial open rotor engine design.

Noise exposure during ambulance flights and repatriation operations.

Science.gov (United States)

Küpper, Thomas E; Zimmer, Bernd; Conrad, Gerson; Jansing, Paul; Hardt, Aline

2010-01-01

Although ambulance flights are routine work and thousands of employees work in repatriation organizations, there is no data on noise exposure which may be used for preventive advice. We investigated the noise exposure of crews working in ambulance flight organizations for international patient repatriation to get the data for specific guidelines concerning noise protection. Noise levels inside Learjet 35A, the aircraft type which is most often used for repatriation operations, were collected from locations where flight crews typically spend their time. A sound level meter class 1 meeting the DIN IEC 651 requirements was used for noise measurements, but several factors during the real flight situations caused a measurement error of ~3%. Therefore, the results fulfill the specifications for class 2. The data was collected during several real repatriation operations and was combined with the flight data (hours per day) regarding the personnel to evaluate the occupationally encountered equivalent noise level according to DIN 45645-2. The measured noise levels were safely just below the 85 dB(A) threshold and should not induce permanent threshold shifts, provided that additional high noise exposure by non-occupational or private activities was avoided. As the levels of the noise produced by the engines outside the cabin are significantly above the 85 dB(A) threshold, the doors of the aircraft must be kept closed while the engines are running, and any activity performed outside the aircraft - or with the doors opened while the engines are running - must be done with adequate noise protection. The new EU noise directive (2003/10/EG) states that protective equipment must be made available to the aircrew to protect their hearing, though its use is not mandatory.

NASA's Pursuit of Low-Noise Propulsion for Low-Boom Commercial Supersonic Vehicles

Science.gov (United States)

Bridges, James; Brown, Clifford A.; Seidel, Jonathan A.

2018-01-01

Since 2006, when the Fundamental Aeronautics Program was instituted within NASA's Aeronautics Mission Directorate, there has been a Project looking at the technical barriers to commercial supersonic flight. Among the barriers is the noise produced by aircraft during landing and takeoff. Over the years that followed, research was carried out at NASA aeronautics research centers, often in collaboration with academia and industry, addressing the problem. In 2013, a high-level milestone was established, described as a Technical Challenge, with the objective of demonstrating the feasibility of a low-boom supersonic airliner that could meet current airport noise regulations. The Technical Challenge was formally called "Low Noise Propulsion for Low Boom Aircraft", and was completed in late 2016. This paper reports the technical findings from this Technical Challenge, reaching back almost 10 years to review the technologies and tools that were developed along the way. It also discusses the final aircraft configuration and propulsion systems required for a supersonic civilian aircraft to meet noise regulations using the technologies available today. Finally, the paper documents the model-scale tests that validated the acoustic performance of the study aircraft.

Identification and Reduction of Turbomachinery Noise, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Communities near airports are often exposed to high noise levels due to low flying aircraft in the takeoff and landing phases of flight. Propulsion source noise is...

Noise Pollution and Health Effects

Directory of Open Access Journals (Sweden)

Geravandi

2015-01-01

Full Text Available Background Noise pollution is of particular importance due to the physical and psychological effects on humans. Noise is a stressor that affects the autonomic nervous system and the endocrine system. Noise is also a threat to marine and terrestrial ecosystems. Health risks from noise are correlated with road traffic. In other words, noise health effects are the health consequences of elevated sound levels. Objectives This study aims to determine the effect of noise pollution (near roadways on health issues in Ahvaz, Iran. Materials and Methods In this cross-sectional study, equivalent sound pressure level were measured by sound level meters TES-1353 in 75 locations around 4 roadways, which had a high load of traffic in Ahvaz City during day time. During the study, 820 measurements were recorded at measuring stations, for 7 days per week with 1-hour interval between each measurement. Statistical analysis was carried out by SPSS software. Results According to the research findings, the equivalent sound pressure levels in all stations were 76.28 ± 3.12 dB (Mean ± SD. According to sound measurements and the survey questionnaire, noise pollution is higher than EPA (US Environmental Protection Agency and Iran standard level. Based on result of this study the worst noise health effects were the nervousness and sleep quality during 2012. Conclusions According to the results of this study, with increasing load of traffic, there is an increasing need for proper consideration plans to control noise pollution and prevent its effects.

High-Lift Propeller Noise Prediction for a Distributed Electric Propulsion Flight Demonstrator

Science.gov (United States)

Nark, Douglas M.; Buning, Pieter G.; Jones, William T.; Derlaga, Joseph M.

2017-01-01

Over the past several years, the use of electric propulsion technologies within aircraft design has received increased attention. The characteristics of electric propulsion systems open up new areas of the aircraft design space, such as the use of distributed electric propulsion (DEP). In this approach, electric motors are placed in many different locations to achieve increased efficiency through integration of the propulsion system with the airframe. Under a project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR), NASA is designing a flight demonstrator aircraft that employs many "high-lift propellers" distributed upstream of the wing leading edge and two cruise propellers (one at each wingtip). As the high-lift propellers are operational at low flight speeds (take-off/approach flight conditions), the impact of the DEP configuration on the aircraft noise signature is also an important design consideration. This paper describes efforts toward the development of a mulit-fidelity aerodynamic and acoustic methodology for DEP high-lift propeller aeroacoustic modeling. Specifically, the PAS, OVERFLOW 2, and FUN3D codes are used to predict the aerodynamic performance of a baseline high-lift propeller blade set. Blade surface pressure results from the aerodynamic predictions are then used with PSU-WOPWOP and the F1A module of the NASA second generation Aircraft NOise Prediction Program to predict the isolated high-lift propeller noise source. Comparisons of predictions indicate that general trends related to angle of attack effects at the blade passage frequency are captured well with the various codes. Results for higher harmonics of the blade passage frequency appear consistent for the CFD based methods. Conversely, evidence of the need for a study of the effects of increased azimuthal grid resolution on the PAS based results is indicated and will be pursued in future work. Overall, the results indicate that the computational

Measured Noise from Small Unmanned Aerial Vehicles

Science.gov (United States)

Cabell, Randolph; McSwain, Robert; Grosveld, Ferdinand

2016-01-01

Proposed uses of small unmanned aerial vehicles (UAVs), including home package delivery, have the potential to expose large portions of communities to a new noise source. This paper discusses results of flyover noise measurements of four small UAVs, including an internal combustion-powered model airplane and three battery-powered multicopters. Basic noise characteristics of these vehicles are discussed, including spectral properties and sound level metrics such as sound pressure level, effective perceived noise level, and sound exposure level. The size and aerodynamic characteristics of the multicopters in particular make their flight path susceptible to atmospheric disturbances such as wind gusts. These gusts, coupled with a flight control system that varies rotor speed to maintain vehicle stability, create an unsteady acoustic signature. The spectral variations resulting from this unsteadiness are explored, in both hover and flyover conditions for the multicopters. The time varying noise, which differs from the relatively steady noise generated by large transport aircraft, may complicate the prediction of human annoyance using conventional sound level metrics.

Definition of 1992 Technology Aircraft Noise Levels and the Methodology for Assessing Airplane Noise Impact of Component Noise Reduction Concepts

Science.gov (United States)

Kumasaka, Henry A.; Martinez, Michael M.; Weir, Donald S.

1996-01-01

This report describes the methodology for assessing the impact of component noise reduction on total airplane system noise. The methodology is intended to be applied to the results of individual study elements of the NASA-Advanced Subsonic Technology (AST) Noise Reduction Program, which will address the development of noise reduction concepts for specific components. Program progress will be assessed in terms of noise reduction achieved, relative to baseline levels representative of 1992 technology airplane/engine design and performance. In this report, the 1992 technology reference levels are defined for assessment models based on four airplane sizes - an average business jet and three commercial transports: a small twin, a medium sized twin, and a large quad. Study results indicate that component changes defined as program final goals for nacelle treatment and engine/airframe source noise reduction would achieve from 6-7 EPNdB reduction of total airplane noise at FAR 36 Stage 3 noise certification conditions for all of the airplane noise assessment models.

Relationship between exposure to multiple noise sources and noise annoyance

NARCIS (Netherlands)

Miedema, H.M.E.

2004-01-01

Relationships between exposure to noise [metric: day-night level (DNL) or day-evening-night level (DENL)] from a single source (aircraft, road traffic, or railways) and annoyance based on a large international dataset have been published earlier. Also for stationary sources relationships have been

Aircraft Test & Evaluation Facility (Hush House)

Data.gov (United States)

Federal Laboratory Consortium — The Aircraft Test and Evaluation Facility (ATEF), or Hush House, is a noise-abated ground test sub-facility. The facility's controlled environment provides 24-hour...

The effects of low frequency noise on mental performance and annoyance.

Science.gov (United States)

Alimohammadi, Iraj; Sandrock, Stephan; Gohari, Mahmoud Reza

2013-08-01

Low frequency noise (LFN) as background noise in urban and work environments is emitted from many artificial sources such as road vehicles, aircraft, and air movement machinery including wind turbines, compressors, and ventilation or air conditioning units. In addition to objective effects, LFN could also cause noise annoyance and influence mental performance; however, there are no homogenous findings regarding this issue. The purpose of this research was to study the effects of LFN on mental performance and annoyance, as well as to consider the role of extraversion and neuroticism on the issue. This study was conducted on 90 students of Iran University of Medical Sciences (54 males and 36 females). The mean age of the students was 23.46 years (SD = 1.97). Personality traits and noise annoyance were measured by using Eysenck Personality Inventory and a 12-scale self-reported questionnaire, respectively. Stroop and Cognitrone computerized tests measured mental performance of participants each exposed to 50 and 70 dBA of LFN and silence. LFNs were produced by Cool Edit Pro 2.1 software. There was no significant difference between mental performance parameters under 50 and 70 dBA of LFN, whereas there were significant differences between most mental performance parameters in quiet and under LFN (50 and 70 dBA). This research showed that LFN, compared to silence, increased the accuracy and the test performance speed (p  0.01). Introverts conducted the tests faster than extraverts (p mental performance. It seems that LFN has increased arousal level of participants, and extraversion has a considerable impact on mental performance.

A Concept for Multi-Criteria Environmental Assessment of Aircraft Trajectories

Directory of Open Access Journals (Sweden)

Sigrun Matthes

2017-08-01

Full Text Available Comprehensive assessment of the environmental aspects of flight movements is of increasing interest to the aviation sector as a potential input for developing sustainable aviation strategies that consider climate impact, air quality and noise issues simultaneously. However, comprehensive assessments of all three environmental aspects do not yet exist and are in particular not yet operational practice in flight planning. The purpose of this study is to present a methodology which allows to establish a multi-criteria environmental impact assessment directly in the flight planning process. The method expands a concept developed for climate optimisation of aircraft trajectories, by representing additionally air quality and noise impacts as additional criteria or dimensions, together with climate impact of aircraft trajectory. We present the mathematical framework for environmental assessment and optimisation of aircraft trajectories. In that context we present ideas on future implementation of such advanced meteorological services into air traffic management and trajectory planning by relying on environmental change functions (ECFs. These ECFs represent environmental impact due to changes in air quality, noise and climate impact. In a case study for Europe prototype ECFs are implemented and a performance assessment of aircraft trajectories is performed for a one-day traffic sample. For a single flight fuel-optimal versus climate-optimized trajectory solution is evaluated using prototypic ECFs and identifying mitigation potential. The ultimate goal of such a concept is to make available a comprehensive assessment framework for environmental performance of aircraft operations, by providing key performance indicators on climate impact, air quality and noise, as well as a tool for environmental optimisation of aircraft trajectories. This framework would allow studying and characterising changes in traffic flows due to environmental optimisation, as well

Automated Design of Noise-Minimal, Safe Rotorcraft Trajectories

Science.gov (United States)

Morris, Robert A.; Venable, K. Brent; Lindsay, James

2012-01-01

NASA and the international community are investing in the development of a commercial transportation infrastructure that includes the increased use of rotorcraft, specifically helicopters and aircraft such as a 40-passenger civil tilt rotors. Rotorcraft have a number of advantages over fixed wing aircraft, primarily in not requiring direct access to the primary fixed wing runways. As such they can operate at an airport without directly interfering with major air carrier and commuter aircraft operations. However, there is significant concern over the impact of noise on the communities surrounding the transportation facilities. In this paper we propose to address the rotorcraft noise problem by exploiting powerful search techniques coming from artificial intelligence, coupled with simulation and field tests, to design trajectories that are expected to improve on the amount of ground noise generated. This paper investigates the use of simulation based on predictive physical models to facilitate the search for low-noise trajectories using a class of automated search algorithms called local search. A novel feature of this approach is the ability to incorporate constraints into the problem formulation that addresses passenger safety and comfort.

The role of Urbis' noise and noise effects maps in local policy

NARCIS (Netherlands)

Borst, H.C.

2001-01-01

An important aspect of the EU noise policy is mapping of noise and noise effects and the formulation of noise action plans. In the Netherlands, due to the new policy on noise (MIG), the municipalities will be responsible for the formulation of a local noise policy. An instrument for the assessment

Noise Reduction Potential of Cellular Metals

Directory of Open Access Journals (Sweden)

Björn Hinze

2012-06-01

Full Text Available Rising numbers of flights and aircrafts cause increasing aircraft noise, resulting in the development of various approaches to change this trend. One approach is the application of metallic liners in the hot gas path of aero-engines. At temperatures of up to 600 °C only metallic or ceramic structures can be used. Due to fatigue loading and the notch effect of the pores, mechanical properties of porous metals are superior to the ones of ceramic structures. Consequently, cellular metals like metallic foams, sintered metals, or sintered metal felts are most promising materials. However, acoustic absorption depends highly on pore morphology and porosity. Therefore, both parameters must be characterized precisely to analyze the correlation between morphology and noise reduction performance. The objective of this study is to analyze the relationship between pore morphology and acoustic absorption performance. The absorber materials are characterized using image processing based on two dimensional microscopy images. The sound absorption properties are measured using an impedance tube. Finally, the correlation of acoustic behavior, pore morphology, and porosity is outlined.

Hearing status among aircraft maintenance personnel in a commercial airline company

Directory of Open Access Journals (Sweden)

Greta Smedje

2011-01-01

Full Text Available The aim was to study subjective and objective hearing loss in a population of aircraft maintenance workers and identify predictors. A total of 327 aircraft maintenance personnel answered a self-administered work environment questionnaire (response rate 76% and underwent audiometric test. The mean values for the hearing threshold at 3, 4, and 6 kHz for the ear with the most hearing loss were compared with a Swedish population database of persons not occupationally exposed to noise. Equivalent noise exposure during a working day was measured. Relationships between subjective and objective hearing loss and possible predictors (age, years of employment, self-reported exposure to solvents, blood pressure, and psycho-social factors were analyzed by multiple logistic regression. At younger ages (<40 years, aircraft maintenance workers had higher hearing thresholds (1-3 dB compared to the reference group, but such a difference was not found in older employees. Relationships were found between age and objective hearing loss, and between exposure to solvents and reported subjective hearing loss. Equivalent noise exposure during working days were 70-91 dB(A with a maximal noise level of 119 dB(A. Aircraft maintenance workers are exposed to equivalent noise levels above the Swedish occupational standard, including some very high peak exposures. Younger employees have a higher age-matched hearing threshold level compared with a reference group. Thus, there is a need for further preventive measures.

Real-time terminal area trajectory planning for runway independent aircraft

Science.gov (United States)

Xue, Min

The increasing demand for commercial air transportation results in delays due to traffic queues that form bottlenecks along final approach and departure corridors. In urban areas, it is often infeasible to build new runways, and regardless of automation upgrades traffic must remain separated to avoid the wakes of previous aircraft. Vertical or short takeoff and landing aircraft as Runway Independent Aircraft (RIA) can increase passenger throughput at major urban airports via the use of vertiports or stub runways. The concept of simultaneous non-interfering (SNI) operations has been proposed to reduce traffic delays by creating approach and departure corridors that do not intersect existing fixed-wing routes. However, SNI trajectories open new routes that may overfly noise-sensitive areas, and RIA may generate more noise than traditional jet aircraft, particularly on approach. In this dissertation, we develop efficient SNI noise abatement procedures applicable to RIA. First, we introduce a methodology based on modified approximated cell-decomposition and Dijkstra's search algorithm to optimize longitudinal plane (2-D) RIA trajectories over a cost function that minimizes noise, time, and fuel use. Then, we extend the trajectory optimization model to 3-D with a k-ary tree as the discrete search space. We incorporate geography information system (GIS) data, specifically population, into our objective function, and focus on a practical case study: the design of SNI RIA approach procedures to Baltimore-Washington International airport. Because solutions were represented as trim state sequences, we incorporated smooth transition between segments to enable more realistic cost estimates. Due to the significant computational complexity, we investigated alternative more efficient optimization techniques applicable to our nonlinear, non-convex, heavily constrained, and discontinuous objective function. Comparing genetic algorithm (GA) and adaptive simulated annealing (ASA

A Method for Simulation of Rotorcraft Fly-In Noise for Human Response Studies

Science.gov (United States)

Rizzi, Stephen A.; Christian, Andrew

2015-01-01

The low frequency content of rotorcraft noise allows it to be heard over great distances. This factor contributes to the disruption of natural quiet in national parks and wilderness areas, and can lead to annoyance in populated areas. Further, it can result in detection at greater distances compared to higher altitude fixed wing aircraft operations. Human response studies conducted in the field are made difficult since test conditions are difficult to control. Specifically, compared to fixed wing aircraft, the source noise itself may significantly vary over time even for nominally steady flight conditions, and the propagation of that noise is more variable due to low altitude meteorological conditions. However, it is possible to create the salient features of rotorcraft fly-in noise in a more controlled laboratory setting through recent advancements made in source noise synthesis, propagation modeling and reproduction. This paper concentrates on the first two of these. In particular, the rotorcraft source noise pressure time history is generated using single blade passage signatures from the main and tail rotors. These may be obtained from either acoustic source noise predictions or back-propagation of ground-based measurements. Propagation effects include atmospheric absorption, spreading loss, Doppler shift, and ground plane reflections.

Evaluation of piezoceramic actuators for control of aircraft interior noise

Science.gov (United States)

Silcox, Richard J.; Lefebvre, Sylvie; Metcalf, Vern L.; Beyer, Todd B.; Fuller, Chris R.

1992-01-01

Results of an experiment to evaluate piezoceramic actuators as the control actuator for active control of interior noise in a large-scale fuselage model are presented. Control was demonstrated for tonal excitation using a time domain least mean squares algorithm. A maximum of four actuator channels and six error signals were used. The actuators were employed for control of noise at frequencies where interior cavity modes were the dominant response and for driven acoustic responses where a structure resonance was dominant. Global reductions of 9 to 12 dB were obtained for the cases examined. The most effective configuration of skin-mounted actuators was found to be a pure in-plane forcing function as opposed to a bending excitation. The frame-mounted actuators were found to be equally effective as the skin-mounted actuators. However, both configurations resulted in local regions of unacceptably high vibration response in the structure.

Does exposure to aircraft noise increase the mortality from cardiovascular disease in the population living in the vicinity of airports? Results of an ecological study in France

Directory of Open Access Journals (Sweden)

Anne-Sophie Evrard

2015-01-01

Full Text Available The impact of aircraft noise on health is of growing concern. We investigated the relationship between this exposure and mortality from cardiovascular disease, coronary heart disease, myocardial infarction, and stroke. We performed an ecological study on 161 communes (commune being the smallest administrative unit in France close to the following three major French airports: Paris-Charles de Gaulle, Lyon Saint-Exupéry, and Toulouse-Blagnac. The mortality data were provided by the French Center on Medical Causes of Death for the period 2007-2010. Based on the data provided by the French Civil Aviation Authority, a weighted average exposure to aircraft noise (L den AEI was computed at the commune level. A Poisson regression model with commune-specific random intercepts, adjusted for potential confounding factors including air pollution, was used to investigate the association between mortality rates and L den AEI. Positive associations were observed between L den AEI and mortality from cardiovascular disease [adjusted mortality rate ratio (MRR per 10 dB(A increase in L den AEI = 1.18; 95% confidence interval (CI: 1.11-1.25], coronary heart disease [MRR = 1.24 (1.12-1.36], and myocardial infarction [MRR = 1.28 (1.11-1.46]. Stroke mortality was more weakly associated with L den AEI [MRR = 1.08 (0.97-1.21]. These significant associations were not attenuated after the adjustment for air pollution. The present ecological study supports the hypothesis of an association between aircraft noise exposure and mortality from cardiovascular disease, coronary heart disease, and myocardial infarction. However, the potential for ecological bias and the possibility that this association could be due to residual confounding cannot be excluded.

14 CFR Appendix H to Part 36 - Noise Requirements For Helicopters Under Subpart H

Science.gov (United States)

2010-01-01

... Subpart H H Appendix H to Part 36 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Pt. 36, App. H Appendix H to Part 36—Noise Requirements For Helicopters Under Subpart H part a—reference conditions Sec. H36...

Study of double wall panels for use in propeller driven aircraft

Science.gov (United States)

Atwal, M.; Bernhard, R.

1984-05-01

Propeller driven aircraft have exhibited high levels of interior noise. Most absorption materials are not effective at low frequencies where maximum noise levels occur. Two panels separated by an air gap are suggested as an alternative means of noise attenuation. This design produces an impedance mismatch where a sound wave travels backwards to the source. The higher the impedance, the higher the reflected soundwave intensity. Two aluminum panels with helium in between and two panels with one being perforated were investigated. Helium increases the transmission loss because of a greater impedance mismatch than air. The transmission loss of the unperforated panel is higher throughout the frequency range tested.

Noise annoyance from wind turbines a review

International Nuclear Information System (INIS)

Pedersen, Eja

2003-08-01

This study summarises present knowledge on noise perception and annoyances from wind turbines in areas were people live or spend recreation time. There are two main types of noise from a wind turbine: mechanical noise and aerodynamic noise. The aerodynamic noise emits from the rotor blades passing the air. It has a swishing character with a modulation that makes it noticeable from the background noise. This part of the wind turbine noise was found to be the most annoying. Field studies performed among people living in the vicinity of wind turbines showed that there was a correlation between sound pressure level and noise annoyance, but annoyance was also influenced by visual factors such as the attitude to wind turbines' impact on the landscape. Noise annoyance was found at lower sound pressure levels than in studies of annoyance from traffic noise. There is no scientific evidence that noise at levels created by wind turbines could cause health problems other than annoyance. No studies on noise from wind turbines in wilderness areas have been found, but the reaction to other noise sources such as aircraft have been studied. In recreational areas, the expectation of quietness is high among visitors, but wind turbines are, in contrary to aircraft, stationary and could be avoided by recreationists. The visual impact of wind turbines might though be the dominant source of annoyance. Regulations on noise from wind turbines are based on different principles. Some states, e.g. Denmark, have a special legislation concerning wind turbines, while others, like Sweden, have used recommendations originally developed for a different noise source. The noise level could either be absolute, as in Germany, or related to the background noise level as in France. This background noise level could be standardised, measured or related to wind speed

Evaluation of noise pollution level based upon community exposure and response data

Science.gov (United States)

Edmiston, R. D.

1972-01-01

The results and procedures are reported from an evaluation of noise pollution level as a predictor of annoyance, based on aircraft noise exposure and community response data. The measures of noise exposure presented include composite noise rating, noise exposure forecast, noise and number index. A proposed measure as a universal noise exposure measure for noise pollution level (L sub NP) is discussed.

Aeroacoustic Validation of Installed Low Noise Propulsion for NASA's N+2 Supersonic Airliner

Science.gov (United States)

Bridges, James

2018-01-01

An aeroacoustic test was conducted at NASA Glenn Research Center on an integrated propulsion system designed to meet noise regulations of ICAO Chapter 4 with 10EPNdB cumulative margin. The test had two objectives: to demonstrate that the aircraft design did meet the noise goal, and to validate the acoustic design tools used in the design. Variations in the propulsion system design and its installation were tested and the results compared against predictions. Far-field arrays of microphones measured the acoustic spectral directivity, which was transformed to full scale as noise certification levels. Phased array measurements confirmed that the shielding of the installation model adequately simulated the full aircraft and provided data for validating RANS-based noise prediction tools. Particle image velocimetry confirmed that the flow field around the nozzle on the jet rig mimicked that of the full aircraft and produced flow data to validate the RANS solutions used in the noise predictions. The far-field acoustic measurements confirmed the empirical predictions for the noise. Results provided here detail the steps taken to ensure accuracy of the measurements and give insights into the physics of exhaust noise from installed propulsion systems in future supersonic vehicles.

Data Quality Assurance for Supersonic Jet Noise Measurements

Science.gov (United States)

Brown, Clifford A.; Henderson, Brenda S.; Bridges, James E.

2010-01-01

The noise created by a supersonic aircraft is a primary concern in the design of future high-speed planes. The jet noise reduction technologies required on these aircraft will be developed using scale-models mounted to experimental jet rigs designed to simulate the exhaust gases from a full-scale jet engine. The jet noise data collected in these experiments must accurately predict the noise levels produced by the full-scale hardware in order to be a useful development tool. A methodology has been adopted at the NASA Glenn Research Center s Aero-Acoustic Propulsion Laboratory to insure the quality of the supersonic jet noise data acquired from the facility s High Flow Jet Exit Rig so that it can be used to develop future nozzle technologies that reduce supersonic jet noise. The methodology relies on mitigating extraneous noise sources, examining the impact of measurement location on the acoustic results, and investigating the facility independence of the measurements. The methodology is documented here as a basis for validating future improvements and its limitations are noted so that they do not affect the data analysis. Maintaining a high quality jet noise laboratory is an ongoing process. By carefully examining the data produced and continually following this methodology, data quality can be maintained and improved over time.

The effects of railway noise on sleep medication intake: Results from the ALPNAP-study

Directory of Open Access Journals (Sweden)

P Lercher

2010-01-01

Full Text Available In the 1980s/90s, a number of socio-acoustic surveys and laboratory studies on railway noise effects have observed less reported disturbance/interference with sleep at the same exposure level compared with other modes of transportation. This lower grade of disturbance has received the label "railway bonus", was implemented in noise legislation in a number of European countries and was applied in planning and environmental impact assessments. However, majority of the studies investigating physiological outcomes did not find the bespoke difference. In a telephone survey (N=1643 we investigated the relationship between railway noise and sleep medication intake and the impact of railway noise events on motility parameters during night was assessed with contact-free high resolution actimetry devices. Multiple logistic regression analysis with cubic splines was applied to assess the probability of sleep medication use based on railway sound level and nine covariates. The non-linear exposure-response curve showed a statistically significant leveling off around 60 dB (A, Lden. Age, health status and trauma history were the most important covariates. The results were supported also by a similar analysis based on the indicator "night time noise annoyance". No railway bonus could be observed above 55 dB(A, Lden. In the actimetry study, the slope of rise of train noise events proved to be almost as important a predictor for motility reactions as was the maximum sound pressure level - an observation which confirms similar findings from laboratory experiments and field studies on aircraft noise and sleep disturbance. Legislation using a railway bonus will underestimate the noise impact by about 10 dB (A, Lden under the conditions comparable with those in the survey study. The choice of the noise calculation method may influence the threshold for guideline setting.

The effects of railway noise on sleep medication intake: results from the ALPNAP-study.

Science.gov (United States)

Lercher, P; Brink, M; Rudisser, J; Van Renterghem, T; Botteldooren, D; Baulac, M; Defrance, J

2010-01-01

In the 1980s/90s, a number of socio-acoustic surveys and laboratory studies on railway noise effects have observed less reported disturbance/interference with sleep at the same exposure level compared with other modes of transportation. This lower grade of disturbance has received the label "railway bonus", was implemented in noise legislation in a number of European countries and was applied in planning and environmental impact assessments. However, majority of the studies investigating physiological outcomes did not find the bespoke difference. In a telephone survey (N=1643) we investigated the relationship between railway noise and sleep medication intake and the impact of railway noise events on motility parameters during night was assessed with contact-free high resolution actimetry devices. Multiple logistic regression analysis with cubic splines was applied to assess the probability of sleep medication use based on railway sound level and nine covariates. The non-linear exposure-response curve showed a statistically significant leveling off around 60 dB (A), Lden. Age, health status and trauma history were the most important covariates. The results were supported also by a similar analysis based on the indicator "night time noise annoyance". No railway bonus could be observed above 55 dB(A), Lden. In the actimetry study, the slope of rise of train noise events proved to be almost as important a predictor for motility reactions as was the maximum sound pressure level - an observation which confirms similar findings from laboratory experiments and field studies on aircraft noise and sleep disturbance. Legislation using a railway bonus will underestimate the noise impact by about 10 dB (A), Lden under the conditions comparable with those in the survey study. The choice of the noise calculation method may influence the threshold for guideline setting.

Analysis of modeling aircraft noise with the Nord2000 noise model

Science.gov (United States)

2012-10-31

This report provides comparisons between AEDT/INM and the Nord 2000 Noise Models for the following parameters: ground type, simple terrain (downward slope, upward slope, hill), temperature and humidity, temperature gradients (positive and negative), ...

Modeling energy and reproductive costs in caribou exposed to low flying military jet aircraft

Directory of Open Access Journals (Sweden)

B.R. Luick

1996-01-01

Full Text Available We used simulation modeling to estimate the effect of low-flying military jet aircraft on the productivity of caribou. The base model (CARIBOU, CWS Whitehorse, Yukon Territory uses daily intake and expenditure of energy to assess the condition of female caribou throughout the annual cycle. The activity budget of the model caribou was adjusted based on field observations of responses to noise disturbance. A subroutine was added that predicted the likelihood of conception based on fall body fat weight. Caribou responses to overflights were evaluated by equipping free-ranging caribou with radio collars and activity sensors that could distinguish between resting and active periods. Collared animals were exposed to 110 overflights by A-10, F-15 and F- 16 jet aircraft during late-winter, post-calving and the insect season. Noise exposure levels for individual animals either were measured directly with collar-mounted dosimeters or were estimated based on the proximity of the caribou to the aircraft during the overflight. A Time-averaged Sound Level (LT was calculated from the total daily noise exposure for each animal and linear regression was used to evaluate the influence of daily noise exposure on daily hours spent resting. Results of these analyses then were used to modify the time budgets in the CARIBOU model. That is, if time spent resting declined, then time spent in the two rest classes (lying and standing were proportionately redistributed into the three active classes (foraging, walking and running. Model simulations indicated that caribou increased forage intake in response to increased noise exposure, but it also predicted that increased noise exposure would cause a reduced accumulation of body fat. Because body fat in fall has successfully been used to predict the probability of pregnancy (see Gerhart et al, 1993, this relationship was used in the model. Preliminary model simulations indicate that increased noise exposure decreases the

Noise, impulse noise, and other physical factors: combined effects on hearing.

Science.gov (United States)

Pekkarinen, J

1995-01-01

In most of the epidemiologic studies conducted during the last 20 years, impulse noise caused increased risk of hearing loss in comparison to continuous noise with the same acoustical energy. The interaction between noise exposure (broadband at 100 dB(A)) and hand-arm vibration (125 Hz at 2 ms-2 acceleration level) has been proven for people having vibration-induced white finger symptoms. This interaction is evidenced as a permanent hearing loss. However, why the interaction is seen only in people with VWF is not known. The mechanisms may be related to individual susceptibility, and hypotheses are given on the role of the autonomous nervous system regulating the peripheral vascular reaction. Whole-body vibration (2-10 Hz, at 10 ms-2 level) seems to increase the TTS when noise (broadband at 90 dB(A)) is present. This effect is more pronounced at higher temperatures. The hypothermia protects hearing against the effects of noise in animal studies. The interaction between noise and temperature decrease seems obvious in animal studies. Exercise has both increased and decreased the TTS during noise exposure. The effects have been successfully explained as the depression of the stapedius reflex. Thus, less protection against noise is provided for the inner ear in exercise conditions. The increase of the blood temperature also has been suggested to increase noise-induced TTS during exercise. Electromagnetic fields have been found to cause acoustical interactions in the inner ear. Animal studies and human studies have given contradictory results on the effects of magnetic coil devices on hearing. The MR imaging devices produce noise levels of 82-93 dB, which is not sufficient to produce the risk of permanent hearing loss when short exposure durations are taken into consideration. More systematic research is needed with accurately defined electromagnetic characteristics to reveal the potential interactions. The interactions seem to exist, but relatively high levels and

Improvement of Aircraft Crash Effective Areas for Koeberg Nuclear Power Plant

International Nuclear Information System (INIS)

Momoti, S.; Dongmo, G.B.; Combrink, Y.

2017-01-01

Probabilistic Safety Assessment (PSA): Tool for determining safe functioning of nuclear power plant to meet regulatory requirements; One of the inputs to the PSA are the frequency and consequences of an aircraft crash. Overview: Frequency of Aircraft Crash; Effective Area of an Aircraft Crashing into Koeberg - Aviation Categories, - Shielding of sensitive target buildings; Impact of refining the Effective AreaFrequency of Aircraft Crash

Broadband Shock Noise in Internally-Mixed Dual-Stream Jets

Science.gov (United States)

Bridges, James E.

2009-01-01

Broadband shock noise (BBSN) has been studied in some detail in single-flow jets and recently in dual-stream jets with separate flow exhaust systems. Shock noise is of great concern in these latter cases because of the noise created for the aircraft cabin by the underexpanded nozzle flow at cruise. Another case where shock noise is of concern is in the case of future supersonic aircraft that are expected to have bypass ratios small enough to justify internally mixed exhaust systems, and whose mission will push cycles to the point of imperfectly expanded flows. Dual-stream jets with internally mixed plume have some simplifying aspects relative to the separate flow jets, having a single shock structure given by the common nozzle pressure. This is used to separate the contribution of the turbulent shear layer to the broadband shock noise. Shock structure is held constant while the geometry and strength of the inner and merged shear layers are varying by changing splitter area ratio and core stream temperature. Flow and noise measurements are presented which document the efforts at separating the contribution of the inner shear layer to the broadband shock noise.

The effects of noise reduction technologies on the acceptance of background noise.

Science.gov (United States)

Lowery, Kristy Jones; Plyler, Patrick N

2013-09-01

Directional microphones (D-Mics) and digital noise reduction (DNR) algorithms are used in hearing aids to reduce the negative effects of background noise on performance. Directional microphones attenuate sounds arriving from anywhere other than the front of the listener while DNR attenuates sounds with physical characteristics of noise. Although both noise reduction technologies are currently available in hearing aids, it is unclear if the use of these technologies in isolation or together affects acceptance of noise and/or preference for the end user when used in various types of background noise. The purpose of the research was to determine the effects of D-Mic, DNR, or the combination of D-Mic and DNR on acceptance of noise and preference when listening in various types of background noise. An experimental study in which subjects were exposed to a repeated measures design was utilized. Thirty adult listeners with mild sloping to moderately severe sensorineural hearing loss participated (mean age 67 yr). Acceptable noise levels (ANLs) were obtained using no noise reduction technologies, D-Mic only, DNR only, and the combination of the two technologies (Combo) for three different background noises (single-talker speech, speech-shaped noise, and multitalker babble) for each listener. In addition, preference rankings of the noise reduction technologies were obtained within each background noise (1 = best, 3 = worst). ANL values were significantly better for each noise reduction technology than baseline; and benefit increased significantly from DNR to D-Mic to Combo. Listeners with higher (worse) baseline ANLs received more benefit from noise reduction technologies than listeners with lower (better) baseline ANLs. Neither ANL values nor ANL benefit values were significantly affected by background noise type; however, ANL benefit with D-Mic and Combo was similar when speech-like noise was present while ANL benefit was greatest for Combo when speech spectrum noise was

Partial and Total Annoyance Due to Road Traffic Noise Combined with Aircraft or Railway Noise: Structural Equation Analysis

OpenAIRE

Gille, Laure-Anne; Marquis-Favre, Catherine; Lam, Kin-Che

2017-01-01

Structural equation modeling was used to analyze partial and total in situ annoyance in combined transportation noise situations. A psychophysical total annoyance model and a perceptual total annoyance model were proposed. Results show a high contribution of Noise exposure and Noise sensitivity to Noise annoyance, as well as a causal relationship between noise annoyance and lower Dwelling satisfaction. Moreover, the Visibility of noise source may increase noise annoyance, even when the visibl...

Study of LH2 fueled subsonic passenger transport aircraft

Science.gov (United States)

Brewer, G. D.; Morris, R. E.

1976-01-01

The potential of using liquid hydrogen as fuel in subsonic transport aircraft was investigated to explore an expanded matrix of passenger aircraft sizes. Aircraft capable of carrying 130 passengers 2,780 km (1500 n.mi.); 200 passengers 5,560 km (3000 n.mi.); and 400 passengers on a 9,265 km (5000 n.mi.) radius mission, were designed parametrically. Both liquid hydrogen and conventionally fueled versions were generated for each payload/range in order that comparisons could be made. Aircraft in each mission category were compared on the basis of weight, size, cost, energy utilization, and noise.

Atmospheric/climatic effects of aircraft emissions

International Nuclear Information System (INIS)

Pueschel, R.F.

1996-01-01

Exhaust emissions from aircraft include oxides of nitrogen (NO x ), water vapor (H 2 O), sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), hydrocarbons (HC) and particles (soot and sulfates). These emissions are small compared to industrial/urban surface emissions. However, because (1) atmospheric residence times of exhaust constituents are longer at altitude, particularly in the stratosphere, than they are in the boundary layer, (2) their background concentrations at altitude are lower than those near the surface, (3) the radiation balance is the more sensitive to atmospheric trace constituents the colder the temperature aloft and (4) inter-hemispheric mixing of aircraft effluents is inhibited, aircraft emissions near and above the tropopause and polewards of 40 degrees latitude can be environmentally critical. That's why atmospheric/climatic effects of aircraft emissions have again received scientific, economic and political scrutiny in the last few years, motivated by growth of subsonic traffic at about 5% per year over the past two decades and the advent of a technologically feasible operation of a supersonic high speed commercial transport (HSCT) fleet

Noise measurements on proximity effect bridges

International Nuclear Information System (INIS)

Decker, S.K.; Mercereau, J.E.

1975-01-01

Audio frequency noise density measurements were performed on weakly superconducting proximity effect bridges on using a cooled transformer and room temperature low noise preamplifier. The noise temperature of the measuring system is approximately 4 0 K for a 0.9 Ω resistor. Noise density was measured as a function of bias current and temperature for the bridges. Excess noise above that expected from Johnson noise for a resistor equal to the dynamic resistance of the bridges was observed in the region near the critical current of the device. At high currents compared to the critical current, the noise density closely approaches that given by Johnson noise

Effect of noise on fractal structure

Energy Technology Data Exchange (ETDEWEB)

Serletis, Demitre [Division of Neurosurgery, Hospital for Sick Children, 1504-555 University Avenue, Toronto, Ont., M5G 1X8 (Canada)], E-mail: demitre.serletis@utoronto.ca

2008-11-15

In this paper, I investigate the effect of dynamical noise on the estimation of the Hurst exponent and the fractal dimension of time series. Recently, Serletis et al. [Serletis, Apostolos, Asghar Shahmoradi, Demitre Serletis. Effect of noise on estimation of Lyapunov exponents from a time series. Chaos, Solitons and Fractals, forthcoming] have shown that dynamical noise can make the detection of chaotic dynamics very difficult, and Serletis et al. [Serletis, Apostolos, Asghar Shahmoradi, Demitre Serletis. Effect of noise on the bifurcation behavior of dynamical systems. Chaos, Solitons and Fractals, forthcoming] have shown that dynamical noise can also shift bifurcation points and produce noise-induced transitions, making the determination of bifurcation boundaries difficult. Here I apply the detrending moving average (DMA) method, recently developed by Alessio et al. [Alessio E, Carbone A, Castelli G, Frappietro V. Second-order moving average and scaling of stochastic time series. The Eur Phys J B 2002;27:197-200] and Carbone et al. [Carbone A, Castelli G, Stanley HE. Time-dependent Hurst exponent in financial time series. Physica A 2004;344:267-71; Carbone A, Castelli G, Stanley HE. Analysis of clusters formed by the moving average of a long-range correlated time series. Phys Rev E 2004;69:026105], to estimate the Hurst exponent of a Brownian walk with a Hurst exponent of 0.5, coupled with low and high intensity noise, and show that dynamical noise has no effect on fractal structure.

Hybrid Wing Body Aircraft Acoustic Test Preparations and Facility Upgrades

Science.gov (United States)

Heath, Stephanie L.; Brooks, Thomas F.; Hutcheson, Florence V.; Doty, Michael J.; Haskin, Henry H.; Spalt, Taylor B.; Bahr, Christopher J.; Burley, Casey L.; Bartram, Scott M.; Humphreys, William M.;

Hybrid Prediction Method for Aircraft Interior Noise, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The goal of the project is research and development of methods for application of the Hybrid FE-SEA method to aircraft vibro-acoustic problems. This proposal...

A de-noising algorithm based on wavelet threshold-exponential adaptive window width-fitting for ground electrical source airborne transient electromagnetic signal

Science.gov (United States)

Ji, Yanju; Li, Dongsheng; Yu, Mingmei; Wang, Yuan; Wu, Qiong; Lin, Jun

2016-05-01

The ground electrical source airborne transient electromagnetic system (GREATEM) on an unmanned aircraft enjoys considerable prospecting depth, lateral resolution and detection efficiency, etc. In recent years it has become an important technical means of rapid resources exploration. However, GREATEM data are extremely vulnerable to stationary white noise and non-stationary electromagnetic noise (sferics noise, aircraft engine noise and other human electromagnetic noises). These noises will cause degradation of the imaging quality for data interpretation. Based on the characteristics of the GREATEM data and major noises, we propose a de-noising algorithm utilizing wavelet threshold method and exponential adaptive window width-fitting. Firstly, the white noise is filtered in the measured data using the wavelet threshold method. Then, the data are segmented using data window whose step length is even logarithmic intervals. The data polluted by electromagnetic noise are identified within each window based on the discriminating principle of energy detection, and the attenuation characteristics of the data slope are extracted. Eventually, an exponential fitting algorithm is adopted to fit the attenuation curve of each window, and the data polluted by non-stationary electromagnetic noise are replaced with their fitting results. Thus the non-stationary electromagnetic noise can be effectively removed. The proposed algorithm is verified by the synthetic and real GREATEM signals. The results show that in GREATEM signal, stationary white noise and non-stationary electromagnetic noise can be effectively filtered using the wavelet threshold-exponential adaptive window width-fitting algorithm, which enhances the imaging quality.

Core Noise: Overview of Upcoming LDI Combustor Test

Science.gov (United States)

Hultgren, Lennart S.

2012-01-01

This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Fixed Wing Project. The presentation covers: the emerging importance of core noise due to turbofan design trends and its relevance to the NASA N+3 noise-reduction goal; the core noise components and the rationale for the current emphasis on combustor noise; and the current and planned research activities in the combustor-noise area. Two NASA-sponsored research programs, with particular emphasis on indirect combustor noise, "Acoustic Database for Core Noise Sources", Honeywell Aerospace (NNC11TA40T) and "Measurement and Modeling of Entropic Noise Sources in a Single-Stage Low-Pressure Turbine", U. Illinois/U. Notre Dame (NNX11AI74A) are briefly described. Recent progress in the development of CMC-based acoustic liners for broadband noise reduction suitable for turbofan-core application is outlined. Combustor-design trends and the potential impacts on combustor acoustics are discussed. A NASA GRC developed nine-point lean-direct-injection (LDI) fuel injector is briefly described. The modification of an upcoming thermo-acoustic instability evaluation of the GRC injector in a combustor rig to also provide acoustic information relevant to community noise is presented. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. The Quiet Performance Research Theme of the Fixed Wing Project aims to develop concepts and technologies to dramatically reduce the perceived community noise attributable to aircraft with minimal impact on weight and performance.

The Effects of Noise on Health

National Research Council Canada - National Science Library

Harris, Charles

1997-01-01

.... This is followed by a discussion of noise induced physiological changes, noise as a stress, and on some specialized topics on the effects of impulsive acoustic stimuli, on effects on sleep, and on hearing and health effects of people living under military training routes.

Long-term exposure to transportation noise and air pollution in relation to incident diabetes in the SAPALDIA study.

Science.gov (United States)

Eze, Ikenna C; Foraster, Maria; Schaffner, Emmanuel; Vienneau, Danielle; Héritier, Harris; Rudzik, Franziska; Thiesse, Laurie; Pieren, Reto; Imboden, Medea; von Eckardstein, Arnold; Schindler, Christian; Brink, Mark; Cajochen, Christian; Wunderli, Jean-Marc; Röösli, Martin; Probst-Hensch, Nicole

2017-08-01

Epidemiological studies have inconsistently linked transportation noise and air pollution (AP) with diabetes risk. Most studies have considered single noise sources and/or AP, but none has investigated their mutually independent contributions to diabetes risk. We investigated 2631 participants of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA), without diabetes in 2002 and without change of residence between 2002 and 2011. Using questionnaire and biomarker data, incident diabetes cases were identified in 2011. Noise and AP exposures in 2001 were assigned to participants' residences (annual average road, railway or aircraft noise level during day-evening-night (Lden), total night number of noise events, intermittency ratio (temporal variation as proportion of event-based noise level over total noise level) and nitrogen dioxide (NO2) levels. We applied mixed Poisson regression to estimate the relative risk (RR) of diabetes and their 95% confidence intervals (CI) in mutually-adjusted models. Diabetes incidence was 4.2%. Median [interquartile range (IQR)] road, railway, aircraft noise and NO2 were 54 (10) dB, 32 (11) dB, 30 (12) dB and 21 (15) μg/m3, respectively. Lden road and aircraft were associated with incident diabetes (respective RR: 1.35; 95% CI: 1.02-1.78 and 1.86; 95% CI: 0.96-3.59 per IQR) independently of Lden railway and NO2 (which were not associated with diabetes risk) in mutually adjusted models. We observed stronger effects of Lden road among participants reporting poor sleep quality or sleeping with open windows. Transportation noise may be more relevant than AP in the development of diabetes, potentially acting through noise-induced sleep disturbances. © The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association

Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

The alignment accuracy of the strap-down inertial navigation system (SINS) of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

Aircraft Electric Propulsion Systems Applied Research at NASA

Science.gov (United States)

Clarke, Sean

2015-01-01

Researchers at NASA are investigating the potential for electric propulsion systems to revolutionize the design of aircraft from the small-scale general aviation sector to commuter and transport-class vehicles. Electric propulsion provides new degrees of design freedom that may enable opportunities for tightly coupled design and optimization of the propulsion system with the aircraft structure and control systems. This could lead to extraordinary reductions in ownership and operating costs, greenhouse gas emissions, and noise annoyance levels. We are building testbeds, high-fidelity aircraft simulations, and the first highly distributed electric inhabited flight test vehicle to begin to explore these opportunities.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Adverse Birth Outcomes.

Science.gov (United States)

Nieuwenhuijsen, Mark J; Ristovska, Gordana; Dadvand, Payam

2017-10-19

Introduction: Three recent systematic reviews suggested a relationship between noise exposure and adverse birth outcomes. The aim of this review was to evaluate the evidence for the World Health Organization (WHO) noise guidelines and conduct an updated systematic review of environmental noise, specifically aircraft and road traffic noise and birth outcomes, such as preterm birth, low birth weight, being small for gestational age and congenital malformations. Materials and methods : We reviewed again all the papers on environmental noise and birth outcomes included in the previous three systematic reviews and conducted a systematic search on noise and birth outcomes to update previous reviews. Web of Science, PubMed and Embase electronic databases were searched for papers published between June 2014 (end date of previous systematic review) and December 2016 using a list of specific search terms. Studies were also screened in the reference list of relevant reviews/articles. Further inclusion and exclusion criteria for the studies provided by the WHO expert group were applied. Risk of bias was assessed according to criteria from the Newcastle-Ottawa quality assessment scale for case-control and cohort studies. Finally, we applied the GRADE principles to our systematic review in a reproducible and appropriate way for judgment about quality of evidence. Results: In total, 14 studies are included in this review, six studies on aircraft noise and birth outcomes, five studies (two with more or less the same population) on road traffic noise and birth outcomes and three related studies on total ambient noise that is likely to be mostly traffic noise that met the criteria. The number of studies on environmental noise and birth outcomes is small and the quality of evidence generally ranges from very low to low, particularly in case of the older studies. The quality is better for the more recent traffic noise and birth outcomes studies. As there were too few studies, we did

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Adverse Birth Outcomes

Directory of Open Access Journals (Sweden)

Mark J. Nieuwenhuijsen

2017-10-01

Full Text Available Introduction: Three recent systematic reviews suggested a relationship between noise exposure and adverse birth outcomes. The aim of this review was to evaluate the evidence for the World Health Organization (WHO noise guidelines and conduct an updated systematic review of environmental noise, specifically aircraft and road traffic noise and birth outcomes, such as preterm birth, low birth weight, being small for gestational age and congenital malformations. Materials and methods: We reviewed again all the papers on environmental noise and birth outcomes included in the previous three systematic reviews and conducted a systematic search on noise and birth outcomes to update previous reviews. Web of Science, PubMed and Embase electronic databases were searched for papers published between June 2014 (end date of previous systematic review and December 2016 using a list of specific search terms. Studies were also screened in the reference list of relevant reviews/articles. Further inclusion and exclusion criteria for the studies provided by the WHO expert group were applied. Risk of bias was assessed according to criteria from the Newcastle-Ottawa quality assessment scale for case-control and cohort studies. Finally, we applied the GRADE principles to our systematic review in a reproducible and appropriate way for judgment about quality of evidence. Results: In total, 14 studies are included in this review, six studies on aircraft noise and birth outcomes, five studies (two with more or less the same population on road traffic noise and birth outcomes and three related studies on total ambient noise that is likely to be mostly traffic noise that met the criteria. The number of studies on environmental noise and birth outcomes is small and the quality of evidence generally ranges from very low to low, particularly in case of the older studies. The quality is better for the more recent traffic noise and birth outcomes studies. As there were too few

Jet Noise Modeling for Supersonic Business Jet Application

Science.gov (United States)

Stone, James R.; Krejsa, Eugene A.; Clark, Bruce J.

2004-01-01

This document describes the development of an improved predictive model for coannular jet noise, including noise suppression modifications applicable to small supersonic-cruise aircraft such as the Supersonic Business Jet (SBJ), for NASA Langley Research Center (LaRC). For such aircraft a wide range of propulsion and integration options are under consideration. Thus there is a need for very versatile design tools, including a noise prediction model. The approach used is similar to that used with great success by the Modern Technologies Corporation (MTC) in developing a noise prediction model for two-dimensional mixer ejector (2DME) nozzles under the High Speed Research Program and in developing a more recent model for coannular nozzles over a wide range of conditions. If highly suppressed configurations are ultimately required, the 2DME model is expected to provide reasonable prediction for these smaller scales, although this has not been demonstrated. It is considered likely that more modest suppression approaches, such as dual stream nozzles featuring chevron or chute suppressors, perhaps in conjunction with inverted velocity profiles (IVP), will be sufficient for the SBJ.

State Estimation for Landing Maneuver on High Performance Aircraft

Science.gov (United States)

Suresh, P. S.; Sura, Niranjan K.; Shankar, K.

2018-01-01

State estimation methods are popular means for validating aerodynamic database on aircraft flight maneuver performance characteristics. In this work, the state estimation method during landing maneuver is explored for the first of its kind, using upper diagonal adaptive extended Kalman filter (UD-AEKF) with fuzzy based adaptive tunning of process noise matrix. The mathematical model for symmetrical landing maneuver consists of non-linear flight mechanics equation representing Aircraft longitudinal dynamics. The UD-AEKF algorithm is implemented in MATLAB environment and the states with bias is considered to be the initial conditions just prior to the flare. The measurement data is obtained from a non-linear 6 DOF pilot in loop simulation using FORTRAN. These simulated measurement data is additively mixed with process and measurement noises, which are used as an input for UD-AEKF. Then, the governing states that dictate the landing loads at the instant of touch down are compared. The method is verified using flight data wherein, the vertical acceleration at the aircraft center of gravity (CG) is compared. Two possible outcome of purely relying on the aircraft measured data is highlighted. It is observed that, with the implementation of adaptive fuzzy logic based extended Kalman filter tuned to adapt for aircraft landing dynamics, the methodology improves the data quality of the states that are sourced from noisy measurements.

Reliability of laboratory tests of VSTOL and other long duration noises

Science.gov (United States)

Kryter, K. D.; Peeler, D. J.; Dobbs, M. E.; Lukas, J. S.

1974-01-01

Paired-comparison and magnitude estimations of the subjective noisiness or unacceptability of noise from fixed wing jet aircraft and simulated noise of VSTOL aircraft were obtained from groups of subjects given different instructions. These results suggest that VSTOL noises can be evaluated in terms of their noisiness or unwantedness to people with reasonable accuracy by units of the physical measures designated as PNdBM, with or without tone corrections, and dBD sub 2. Also, that consideration should be given to the use of D sub 2 as an overall frequency weighting function for sound level meters instead of the presently available A weighting. Two new units of noise measurement, PLdB and dB(E), used for predicting subjective noisiness, were found to be less accurate than PNdBM or dBD sub 2 in this regard.

[Effects of urban noise on mental health].

Science.gov (United States)

Belojević, G; Jakovljević, B; Kocijancić, R; Pjerotić, L; Dimitrijević, J

1995-01-01

The results of the latest studies on the effects of urban noise on mental health are presented in this paper. Numerous psychiatric symptoms have been frequently noticed in the population of the settlements with a high level of urban noise: fatigue, headaches, tension, anxiety, irritability, bad concentration, insomnia, whith a consequently high consumption of psychotropic medicines. Higher admission rates in psychiatric hospitals have been noticed from noisy areas in comparison with low noise regions. By use of diagnostic psychiatric interviews it has been shown as well, that in sensitive categories of population positive correlation can be expected between the number of persons with mental disorder and the level of environmental noise. Noise annoyance and sleep disturbance, namely shortening or absence of the sleep phase 4 and REM, are the basic negative psychological effects of noise, with an adverse effect on mental health in general.

How Effective Is Communication Training For Aircraft Crews

Science.gov (United States)

Linde, Charlotte; Goguen, Joseph; Devenish, Linda

1992-01-01

Report surveys communication training for aircraft crews. Intended to alleviate problems caused or worsened by poor communication and coordination among crewmembers. Focuses on two training methods: assertiveness training and grid-management training. Examines theoretical background of methods and attempts made to validate their effectiveness. Presents criteria for evaluating applicability to aviation environment. Concludes communication training appropriate for aircraft crews.

Superconducting and conventional electromagnetic launch system for civil aircraft assisted take-off

OpenAIRE

Bertola, Luca; Cox, Thomas; Wheeler, Patrick; Garvey, Seamus D.

2016-01-01

This paper compares three possible linear motor topologies for an electromagnetic launch system to assist civil aircraft take-off. Assisted launch of civil aircraft has the potential of reducing the required runway length, reducing noise and emissions near airports and improving overall aircraft efficiency through reducing engine thrust requirements. A comparison is made of practical designs of a linear induction motor, a linear permanent magnet synchronous motor and a superconducting linear ...

Measurement of speech levels in the presence of time varying background noise

Science.gov (United States)

Pearsons, K. S.; Horonjeff, R.

1982-01-01

Short-term speech level measurements which could be used to note changes in vocal effort in a time varying noise environment were studied. Knowing the changes in speech level would in turn allow prediction of intelligibility in the presence of aircraft flyover noise. Tests indicated that it is possible to use two second samples of speech to estimate long term root mean square speech levels. Other tests were also performed in which people read out loud during aircraft flyover noise. Results of these tests indicate that people do indeed raise their voice during flyovers at a rate of about 3-1/2 dB for each 10 dB increase in background level. This finding is in agreement with other tests of speech levels in the presence of steady state background noise.

PIV Measurements of Chevrons on F400-Series Tactical Aircraft Nozzle Model

Science.gov (United States)

Bridges, James; Wernet, Mark P.; Frate, Franco C.

2011-01-01

Reducing noise of tactical jet aircraft has taken on fresh urgency as core engine technologies allow higher specific-thrust engines and as society become more concerned for the health of its military workforce. Noise reduction on this application has lagged the commercial field as incentives for quieting military aircraft have not been as strong as in their civilian counterparts. And noise reduction strategies employed on civilian engines may not be directly applicable due to the differences in exhaust system architecture and mission. For instance, the noise reduction technology of chevrons, examined in this study, will need to be modified to take into account the special features of tactical aircraft nozzles. In practice, these nozzles have divergent slats that are tied to throttle position, and at take off the jet flow is highly overexpanded as the nozzle is optimized for cruise altitude rather than sea level. In simple oil flow visualization experiments conducted at the onset of the current test program flow barely stays attached at end of nozzle at takeoff conditions. This adds a new twist to the design of chevrons. Upon reaching the nozzle exit the flow shrinks inward radially, meaning that for a chevron to penetrate the flow it must extend much farther away from the baseline nozzle streamline. Another wrinkle is that with a variable divergence angle on the nozzle, the effective penetration will differ with throttle position and altitude. The final note of realism introduced in these experiments was to simulate the manner in which bypass flow is bled into the nozzle wall in real engines to cool the nozzle, which might cause very fat boundary layer at exit. These factors, along with several other issues specific to the application of chevrons to convergent-divergent nozzles have been explored with particle image velocimetry measurements and are presented in this paper.

Noise sensitivity, rather than noise level, predicts the non-auditory effects of noise in community samples: a population-based survey

Directory of Open Access Journals (Sweden)

Jangho Park

2017-04-01

Full Text Available Abstract Background Excessive noise affects human health and interferes with daily activities. Although environmental noise may not directly cause mental illness, it may accelerate and intensify the development of latent mental disorders. Noise sensitivity (NS is considered a moderator of non-auditory noise effects. In the present study, we aimed to assess whether NS is associated with non-auditory effects. Methods We recruited a community sample of 1836 residents residing in Ulsan and Seoul, South Korea. From July to November 2015, participants were interviewed regarding their demographic characteristics, socioeconomic status, medical history, and NS. The non-auditory effects of noise were assessed using the Center of Epidemiologic Studies Depression, Insomnia Severity index, State Trait Anxiety Inventory state subscale, and Stress Response Inventory-Modified Form. Individual noise levels were recorded from noise maps. A three-model multivariate logistic regression analysis was performed to identify factors that might affect psychiatric illnesses. Results Participants ranged in age from 19 to 91 years (mean: 47.0 ± 16.1 years, and 37.9% (n = 696 were male. Participants with high NS were more likely to have been diagnosed with diabetes and hyperlipidemia and to use psychiatric medication. The multivariable analysis indicated that even after adjusting for noise-related variables, sociodemographic factors, medical illness, and duration of residence, subjects in the high NS group were more than 2 times more likely to experience depression and insomnia and 1.9 times more likely to have anxiety, compared with those in the low NS group. Noise exposure level was not identified as an explanatory value. Conclusions NS increases the susceptibility and hence moderates there actions of individuals to noise. NS, rather than noise itself, is associated with an elevated susceptibility to non-auditory effects.

Communicating airport noise emission data to the general public.

Science.gov (United States)

Gasco, Luis; Asensio, Cesar; de Arcas, Guillermo

2017-05-15

Despite the efforts that the aviation industry has undertaken during the last few decades, noise annoyance remains high, partly because of the continuous transport demands of modern societies and partly because of changes in citizen expectations and their growing environmental concerns. Although modern aircraft are considerably quieter than their predecessors, the number of complaints has not decreased as much as expected. Therefore, the aeronautical sector has tried more sociological and/or psychological strategies to gain acceptance through awareness and community engagement. In this regard, noise communication to the public is crucial for managers and policy makers. Noise information is a difficult technical topic for non-experts, which is an issue that must first be addressed to take advantage of the new possibilities that have recently been opened by the internet and information and communication technologies. In this review paper, we have compiled the literature that shows the increasing importance of communicating noise information from aircraft and the variety of indicators used to communicate with the public. We also examined the methods of representing noise data, using visualization strategies, and new tools airports are currently using to address this communication problem. Copyright © 2017 Elsevier B.V. All rights reserved.

Embedded Acoustic Sensor Array for Engine Fan Noise Source Diagnostic Test: Feasibility of Noise Telemetry via Wireless Smart Sensors

Science.gov (United States)

Zaman, Afroz; Bauch, Matthew; Raible, Daniel

2011-01-01

Aircraft engines have evolved into a highly complex system to meet ever-increasing demands. The evolution of engine technologies has primarily been driven by fuel efficiency, reliability, as well as engine noise concerns. One of the sources of engine noise is pressure fluctuations that are induced on the stator vanes. These local pressure fluctuations, once produced, propagate and coalesce with the pressure waves originating elsewhere on the stator to form a spinning pressure pattern. Depending on the duct geometry, air flow, and frequency of fluctuations, these spinning pressure patterns are self-sustaining and result in noise which eventually radiate to the far-field from engine. To investigate the nature of vane pressure fluctuations and the resulting engine noise, unsteady pressure signatures from an array of embedded acoustic sensors are recorded as a part of vane noise source diagnostics. Output time signatures from these sensors are routed to a control and data processing station adding complexity to the system and cable loss to the measured signal. "Smart" wireless sensors have data processing capability at the sensor locations which further increases the potential of wireless sensors. Smart sensors can process measured data locally and transmit only the important information through wireless communication. The aim of this wireless noise telemetry task was to demonstrate a single acoustic sensor wireless link for unsteady pressure measurement, and thus, establish the feasibility of distributed smart sensors scheme for aircraft engine vane surface unsteady pressure data transmission and characterization.

Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

Science.gov (United States)

Hughes, Christoper E.; Gazzaniga, John A.

2013-01-01

A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

Loading Effect on Tire Noise Radiation

OpenAIRE

Cao, Rui; Bolton, J Stuart

2016-01-01

Noise radiated by tires is a prominent noise pollution source and it is affected by many different parameters. Here, the effect of static load on tire noise radiation in a laboratory environment was investigated. The measurement was conducted by using the Tire Pavement Testing Apparatus (TPTA), on which a loaded tire can be run at speeds up to 50 km/hr; the tire noise was measured using a nearfield microphone method. The tire loading was varied from 500 to 900 pounds, and several different co...

Effects of road traffic background noise on judgments of individual airplane noises. Ph.D. Thesis

Science.gov (United States)

Powell, C. A.

1979-01-01

Two laboratory experiments were conducted to investigate the effects of road-traffic background noise on judgments of individual airplane flyover noises. In the first experiment, 27 subjects judged a set of 16 airplane flyover noises in the presence of traffic-noise sessions of 30-min duration consisting of the combinations of 3 traffic-noise types and 3 noise levels. In the second experiment, 24 subjects judged the same airplane flyover noises in the presence of traffic-noise sessions of 10-min duration consisting of the combinations of 2 traffic-noise types and 4 noise levels. In both experiments the airplane noises were judged less annoying in the presence of high traffic-noise levels than in the presence of low traffic-noise levels.

Landing Gear Door Liners for Airframe Noise Reduction

Science.gov (United States)

Jones, Michael G. (Inventor); Howerton, Brian M. (Inventor); Van De Ven, Thomas (Inventor)

2014-01-01

A landing gear door for retractable landing gear of aircraft includes an acoustic liner. The acoustic liner includes one or more internal cavities or chambers having one or more openings that inhibit the generation of sound at the surface and/or absorb sound generated during operation of the aircraft. The landing gear door may include a plurality of internal chambers having different geometries to thereby absorb broadband noise.

Vienna international airport noise abatement

Directory of Open Access Journals (Sweden)

Heidelinde Jelinek-Nigitz

2016-03-01

Full Text Available Purpose: On the topic of sustainable aviation a study was carried out to measure the difference between the actual change in air traffic noise and the airport’s residents’ perception of the noise change at Vienna International Airport. Therefore, a questionnaire was developed in cooperation with the airport and an online survey was conducted. Design/methodology/approach: For the survey of the opinion of the affected population of the surrounding communities, a web based online questionnaire is created and distributed via various channels including e-mail, and online forums. After the basic structure of the questionnaire had been defined, the questions were developed in cooperation with employees form the environmental department of VIE, who had a sustainable influence on the questions’ order and formulation. As the survey was supposed to be answered by residents around VIE. Findings: Results of the online study show that only parts of the participants are affected by air traffic noise at VIE. Even less experienced a significant change over the last five years. About one third of the participants stated that they are affected by air traffic noise in one way or another. The majority of these people live in Lower Austria, the federal state in which the airport is located. The participants obviously judge air traffic noise during day time more importantly than air traffic noise at night. Research limitations/implications: Due to the low number of returns, no statistically relevant conclusions can be drawn, the results of the survey can be used to make some general statements. Originality/value: Economic growth and deregulation lead to growing aircraft operations. Vienna International Airport with its approximately 260,000 flight movements per year is the biggest airport in Austria and a major hub in Europe. The combination of constantly growing air transport and the resulting noise exposure, as well as the steadily increasing

Noise effects on reproduction— animal experiments

Science.gov (United States)

Takigawa, H.; Sakamoto, H.; Murata, M.; Matsumura, Y.

1988-12-01

Noise effects on fetal development were observed in animals. While the copulatory function was not affected, birth rate decreased when the animals were exposed to noise. An increased number of stunted fetuses was observed when the animals were intermittently exposed. However, malformations in the fetuses increased with exposure to both intermittent and continuous noise. Two phases of hormonal change were observed in connection with noise exposure. One is the initial response phase, characterized by the increment of 11-OHCS in the adrenal gland. The other is the end phenomena phase, characterized by a disorder in central control. It is discussed that the disturbance of fetal development by exposure to noise is related to these changes in the hormonal condition.

HF DBD plasma actuators for reduction of cylinder noise in flow

Science.gov (United States)

Kopiev, V. F.; Kazansky, P. N.; Kopiev, V. A.; Moralev, I. A.; Zaytsev, M. Yu

2017-11-01

Surface high frequency dielectric barrier discharge (HF DBD) was used to reduce flow-induced noise, radiated by circular cylinder in cross flow. Effect of HF DBD actuators is studied for flow velocity up to 80 m s-1 (Reynolds numbers up to 2.18 · 105), corresponding to the typical aircraft landing approach speed. Noise measurements were performed by microphone array in anechoic chamber; averaged flow parameters were studied by particle image velocimetry (PIV). Actuator was powered by high-frequency voltage in hundreds kHz range in steady or modulated mode with the modulation frequency of 0.3-20 kHz (Strouhal number St of 0.4 to 20). It is demonstrated that upstream directed plasma actuators are able to reduce the vortex noise of a cylinder by 10 dB. Noise reduction is accompanied by significant reorganization of the wake behind a cylinder, decreasing both wake width and turbulence level. The physical mechanism related to broadband noise control by HF DBD actuator is also discussed.

Evaluation of noise pollution in oil extracting region of Lavan and the effect of noise enclosure on noise abatement

Directory of Open Access Journals (Sweden)

F. Golbabaei

2007-09-01

Full Text Available Background and aims   Overexposure to industrial noise pollution induce hearing loss workers. Occupational hearing loss may cause interference whit oral communication, so it may  increase the risk of occupational accidents in workplace as well as affects whit social activities.  This study was conducted on Lavan Island, are of oil extracting regions in the south of Iran. The  object of this study was to evaluate noise pollution and determining the effect of noise enclosure  on noise abatement.   Methods   The noise sources were recognized and noise pressure level was measured by CEL- 440. Noise dose of the exposed workers in high level noise area were measured by CEL 272.   Results   Major noise sources were gas turbines, diesel generators, compressors, fans and gas containing pips, noise contour map revealers that noise level were higher than the recommended national exposure limit. The results of workers noise dose show that their noise exposure were  higher than the recommended value, (p<0.001. Finally, by using the results of noise frequency  analysis of different noise sources, the noise pressure level of each sources was determined in   terms of enclosing them.   Conclusion   By enclosing the noise sources, noise pressure levels can be lowered douse to  acceptable levels but limitation of applying enclosure should be regarded.  

Using happiness surveys to value intangibles: The case of airport noise

NARCIS (Netherlands)

van Praag, B.M.S.; Baarsma, B.E.

2005-01-01

We assess the monetary value of the noise damage, caused by aircraft noise nuisance around Amsterdam Airport, as the sum of hedonic house price differentials and a residual cost component. The residual costs are assessed from a survey, including an ordinal life satisfaction scale, on which

A Comparison of Three Random Number Generators for Aircraft Dynamic Modeling Applications

Science.gov (United States)

Grauer, Jared A.

2017-01-01

Three random number generators, which produce Gaussian white noise sequences, were compared to assess their suitability in aircraft dynamic modeling applications. The first generator considered was the MATLAB (registered) implementation of the Mersenne-Twister algorithm. The second generator was a website called Random.org, which processes atmospheric noise measured using radios to create the random numbers. The third generator was based on synthesis of the Fourier series, where the random number sequences are constructed from prescribed amplitude and phase spectra. A total of 200 sequences, each having 601 random numbers, for each generator were collected and analyzed in terms of the mean, variance, normality, autocorrelation, and power spectral density. These sequences were then applied to two problems in aircraft dynamic modeling, namely estimating stability and control derivatives from simulated onboard sensor data, and simulating flight in atmospheric turbulence. In general, each random number generator had good performance and is well-suited for aircraft dynamic modeling applications. Specific strengths and weaknesses of each generator are discussed. For Monte Carlo simulation, the Fourier synthesis method is recommended because it most accurately and consistently approximated Gaussian white noise and can be implemented with reasonable computational effort.

Internal additive noise effects in stochastic resonance using organic field effect transistor

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Yoshiharu; Asakawa, Naoki [Division of Molecular Science, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Matsubara, Kiyohiko [KOOROGI LLC, 6-1585-1-B Sakaino-cho, Kiryu, Gunma 376-0002 (Japan)

2016-08-29

Stochastic resonance phenomenon was observed in organic field effect transistor using poly(3-hexylthiophene), which enhances performance of signal transmission with application of noise. The enhancement of correlation coefficient between the input and output signals was low, and the variation of correlation coefficient was not remarkable with respect to the intensity of external noise, which was due to the existence of internal additive noise following the nonlinear threshold response. In other words, internal additive noise plays a positive role on the capability of approximately constant signal transmission regardless of noise intensity, which can be said “homeostatic” behavior or “noise robustness” against external noise. Furthermore, internal additive noise causes emergence of the stochastic resonance effect even on the threshold unit without internal additive noise on which the correlation coefficient usually decreases monotonically.

Study of noise inside the peshawar airport

International Nuclear Information System (INIS)

Khan, M.; Khan, A.R.; Shah, J.; Noor, S.; Aslam, T.

2007-01-01

The paper deals with the noise-study conducted at five different locations within the vicinity of International Airport, Peshawar (Pakistan). The sites selected for this study were Apron, Concourse Hall, Cargo Shed, Car Parking and Utility Block. Noise-levels were recorded during 'landing' and 'taking off' of aircrafts of six international, flights, operating from this Airport. The average noise levels at Apron, Concourse Hall, Cargo Shed, Car Parking and Utility Block were found to be in the range of 87.2-90.3, 77.7-82.0, 82.6-87.5, 0.1-84.5 and 85.0-85.8 dB (A) respectively. The results are discussed, with reference to permissible occupational noise-exposure limits. The health-impacts due to higher noise-level and their possible remedial measures have also been discussed. (author)

Dependence of Dynamic Modeling Accuracy on Sensor Measurements, Mass Properties, and Aircraft Geometry

Science.gov (United States)

Grauer, Jared A.; Morelli, Eugene A.

2013-01-01

The NASA Generic Transport Model (GTM) nonlinear simulation was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of identified parameters in mathematical models describing the flight dynamics and determined from flight data. Measurements from a typical flight condition and system identification maneuver were systematically and progressively deteriorated by introducing noise, resolution errors, and bias errors. The data were then used to estimate nondimensional stability and control derivatives within a Monte Carlo simulation. Based on these results, recommendations are provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using additional flight conditions and parameter estimation methods, as well as a nonlinear flight simulation of the General Dynamics F-16 aircraft, were compared with these recommendations

Noise annoyance caused by continuous descent approaches compared to regular descent procedures

NARCIS (Netherlands)

White, K.; Arntzen, M.; Walker, F.; Waiyaki, F.M.; Meeter, M.; Bronkhorst, A.W.

2017-01-01

During Continuous Descent Approaches (CDAs) aircraft glide towards the runway resulting in reduced noise and fuel usage. Here, we investigated whether such landings cause less noise annoyance than a regular stepwise approach. Both landing types were compared in a controlled laboratory setting with a

Effect of broadened-specification fuels on aircraft engines and fuel systems

Science.gov (United States)

Rudey, R. A.

1979-01-01

A wide variety of studies on the potential effects of broadened-specification fuels on future aircraft engines and fuel systems are summarized. The compositions and characteristics of aircraft fuels that may be derived from current and future crude-oil sources are described, and the most critical properties that may affect aircraft engines and fuel systems are identified and discussed. The problems that are most likely to be encountered because of changes in selected fuel properties are described; and the related effects on engine performance, component durability and maintenance, and aircraft fuel-system performance are discussed. The ability of current technology to accept possible future fuel-specification changes is discussed, and selected technological advances that can reduce the severity of the potential problems are illustrated.

Noise Effects on Human Performance: A Meta-Analytic Synthesis

Science.gov (United States)

Szalma, James L.; Hancock, Peter A.

2011-01-01

Noise is a pervasive and influential source of stress. Whether through the acute effects of impulse noise or the chronic influence of prolonged exposure, the challenge of noise confronts many who must accomplish vital performance duties in its presence. Although noise has diffuse effects, which are shared in common with many other chronic forms of…

Perm State University HPC-hardware and software services: capabilities for aircraft engine aeroacoustics problems solving

Science.gov (United States)

Demenev, A. G.

2018-02-01

The present work is devoted to analyze high-performance computing (HPC) infrastructure capabilities for aircraft engine aeroacoustics problems solving at Perm State University. We explore here the ability to develop new computational aeroacoustics methods/solvers for computer-aided engineering (CAE) systems to handle complicated industrial problems of engine noise prediction. Leading aircraft engine engineering company, including “UEC-Aviadvigatel” JSC (our industrial partners in Perm, Russia), require that methods/solvers to optimize geometry of aircraft engine for fan noise reduction. We analysed Perm State University HPC-hardware resources and software services to use efficiently. The performed results demonstrate that Perm State University HPC-infrastructure are mature enough to face out industrial-like problems of development CAE-system with HPC-method and CFD-solvers.

Noise-induced effects in population dynamics

Science.gov (United States)

Spagnolo, Bernardo; Cirone, Markus; La Barbera, Antonino; de Pasquale, Ferdinando

2002-03-01

We investigate the role of noise in the nonlinear relaxation of two ecosystems described by generalized Lotka-Volterra equations in the presence of multiplicative noise. Specifically we study two cases: (i) an ecosystem with two interacting species in the presence of periodic driving; (ii) an ecosystem with a great number of interacting species with random interaction matrix. We analyse the interplay between noise and periodic modulation for case (i) and the role of the noise in the transient dynamics of the ecosystem in the presence of an absorbing barrier in case (ii). We find that the presence of noise is responsible for the generation of temporal oscillations and for the appearance of spatial patterns in the first case. In the other case we obtain the asymptotic behaviour of the time average of the ith population and discuss the effect of the noise on the probability distributions of the population and of the local field.

Flap Edge Noise Reduction Fins

Science.gov (United States)

Khorrami, Mehdi R. (Inventor); Choudhan, Meelan M. (Inventor)

2015-01-01

A flap of the type that is movably connected to an aircraft wing to provide control of an aircraft in flight includes opposite ends, wherein at least a first opposite end includes a plurality of substantially rigid, laterally extending protrusions that are spaced apart to form a plurality of fluidly interconnected passageways. The passageways have openings adjacent to upper and lower sides of the flap, and the passageways include a plurality of bends such that high pressure fluid flows from a high pressure region to a low pressure region to provide a boundary condition that inhibits noise resulting from airflow around the end of the flap.

Aviation noise overload in the immediate proximity of the Warsaw-Okecie airport

Science.gov (United States)

Koszarny, Z.; Maziarka, S.

1981-01-01

The results are presented for investigations on noise overload around the Warszawa-Okecie airport on persons inhabiting the area where it exceeds 100 dB for a single aircraft flight. Of 256 subjects, 91.1 percent complained about aircraft noise overload. In the population studied considerable differences were noted respecting the subjective sensitivity scale. Statistical analysis showed numerous correlations between the individual noise sensitivity threshold and the subject's state of health, age, sex, type of work, etc. At the same time investigations demonstrated various forms and levels of disturbance in the organism for individual subjects and groups. The most frequent complaint was chronic fatigue (68.1 percent), followed by nervousness (36.6 percent), frequent headaches (36.2 percent), hearing disturbances (30.0 percent) and sleep disorders (23.9 percent).

Advanced transport aircraft technology

Energy Technology Data Exchange (ETDEWEB)

Winblade, R L

1980-06-01

Various elements of the NASA aircraft energy efficiency program are described. Regarding composite structures, the development of three secondary and three medium-primary components to validate structural and fabrication technology is discussed. In laminar flow control, the design of advanced airfoils having large regions of supercritical flow with features which simplify laminarization are considered. Emphasis is placed on engine performance improvement, directed at developing advanced components to reduce fuel consumption in current production engines, and engine diagnostics aimed at identifying the sources and causes of performance deterioration in high-bypass turbofan engines. In addition, the results of propeller aerodynamic and acoustic tests have substantiated the feasibility of achieving the propeller efficiency goal of 80% and confirmed that the effect of blade sweep on reducing propeller source noise was 5-6 dB.

Passive Techniques for Fan Noise Reduction in New Turbofan Engines: Review

Directory of Open Access Journals (Sweden)

M.Gorj-Bandpy

2013-03-01

Full Text Available Among the various environmental concerns, the aircraft noise item has been constantly growing in importance over the past years. Measures for its reduction at the source as well its mitigation around airports must take into account aspects of medicine and technical design as well as legal and land use planning aspects. Fan noise is one of the principal noise sources in turbofan aero-engines. In this paper a review of the main technologies employed for the reduction of fan noise turbofan engines is presented.

Effect of cigarette smoking on noise-induced hearing loss in workers exposed to occupational noise in China.

Science.gov (United States)

Tao, Liyuan; Davis, Robert; Heyer, Nicholas; Yang, Qiuling; Qiu, Wei; Zhu, Liangliang; Li, Nan; Zhang, Hua; Zeng, Lin; Zhao, Yiming

2013-01-01

Excessive exposure to high noise level environments has the potential to cause noise-induced hearing loss (NIHL), and cigarette smoking has also been shown to have a potential adverse effect on hearing. The aim of this study was to determine whether smoking interacts with noise in the development of hearing loss, and if so, the extent of the contribution from smoking on NIHL. A cross-sectional study was designed to assess the effect of smoking on NIHL in 517 male workers (non-smokers: N = 199; smokers: N = 318) exposed to a high-level industrial noise environment in China. Shift-long temporal waveforms of the noise that workers were exposed to for evaluation of noise exposures, and audiometric threshold measures were obtained on all selected subjects. The subjects used hearing protection devices only within the last 1-2 years. The results suggest that smoking has an adverse effect on NIHL in workers exposed to high level industrial noise, i.e., the median high frequency hearing thresholds were significantly greater in smokers than non-smokers exposed to noise for more than 10 years. This effect was observed at 4.0 and 6.0 kHz. Smoking did not have an adverse effect on NIHL in workers exposed to noise less than 10 years. Multivariate regression analysis revealed that the odds ratio (OR) for high frequency hearing loss (i.e., hearing threshold greater than 40 dB at 4.0 kHz) were 1.94 for smokers in comparison to non-smokers. The results suggest that: (1) smokers have a higher risk of developing high frequency hearing loss than non-smokers with a similar occupational noise exposure, and (2) the interaction between cigarette smoking and high-level noise exposure may be additive. There is a need to develop and analyze a larger database of workers with well-documented exposures and smoking histories for better understanding of the effect of smoking on NIHL incurred from high-level industrial noise exposures. A better understanding of the role of smoking may lead to its

Greenhouse effects of aircraft emissions

International Nuclear Information System (INIS)

Fortuin, J.P.F.; Wauben, W.M.F.; Dorland, R. van; Kelder, H.

1996-01-01

Ranges for direct and indirect greenhouse effects due to present day aircraft emissions are quantified for northern midlatitudes, using the concept of fixed temperature (FT) radiative forcing as calculated with a radiative transfer model. The direct greenhouse effects considered here are from emissions of carbon dioxide, water vapor, and nitrogen dioxide. To calculate the concentration increases of carbon dioxide and stratospheric water vapor, an analytical expression is developed based on a linear approximation of global fuel burn versus time. Unlike the expressions currently used in the literature, the authors' expression does not account for emission rates only, but also for a loss term--hence making it more suitable for shorter lived emittants. For midlatitude summer conditions, a total radiative forcing ranging from 0.04 to 0.09 Wm -2 is calculated for the direct greenhouse effects, whereas for midlatitude winter the range is 0.07 to 0.26 Wm -2 . The indirect greenhouse effects considered here are sulfate aerosol formation from sulfur dioxide emissions, contrail formation from emitted water vapor and condensation nuclei, and ozone formation from NO x emissions. The total radiative forcing coming from these indirect effects range from -0.67 to 0.25 Wm -2 in summer a/nd from -0.36 to 0.21 Wm -2 in winter. Further, the global distribution of NO x and ozone increases from aircraft emissions world-wide are simulated with a three-dimensional chemistry transport model for January and July. The geographical distribution of the radiative forcing associated with the simulated ozone increases is also calculated for these months

Noise Reduction Effect of Multiple-Sampling-Based Signal-Readout Circuits for Ultra-Low Noise CMOS Image Sensors

Directory of Open Access Journals (Sweden)

Shoji Kawahito

2016-11-01

Full Text Available This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs. This paper reveals how the column CMS circuits, together with a pixel having a high-conversion-gain charge detector and low-noise transistor, realizes deep sub-electron read noise levels based on the analysis of noise components in the signal readout chain from a pixel to the column analog-to-digital converter (ADC. The noise measurement results of experimental CISs are compared with the noise analysis and the effect of noise reduction to the sampling number is discussed at the deep sub-electron level. Images taken with three CMS gains of two, 16, and 128 show distinct advantage of image contrast for the gain of 128 (noise(median: 0.29 e−rms when compared with the CMS gain of two (2.4 e−rms, or 16 (1.1 e−rms.

HF DBD plasma actuators for reduction of cylinder noise in flow

International Nuclear Information System (INIS)

Kopiev, V F; Kopiev, V A; Zaytsev, M Yu; Kazansky, P N; Moralev, I A

2017-01-01

Surface high frequency dielectric barrier discharge (HF DBD) was used to reduce flow-induced noise, radiated by circular cylinder in cross flow. Effect of HF DBD actuators is studied for flow velocity up to 80 m s −1 (Reynolds numbers up to 2.18 · 10 5 ), corresponding to the typical aircraft landing approach speed. Noise measurements were performed by microphone array in anechoic chamber; averaged flow parameters were studied by particle image velocimetry (PIV). Actuator was powered by high-frequency voltage in hundreds kHz range in steady or modulated mode with the modulation frequency of 0.3–20 kHz (Strouhal number St of 0.4 to 20). It is demonstrated that upstream directed plasma actuators are able to reduce the vortex noise of a cylinder by 10 dB. Noise reduction is accompanied by significant reorganization of the wake behind a cylinder, decreasing both wake width and turbulence level. The physical mechanism related to broadband noise control by HF DBD actuator is also discussed. (paper)

76 FR 30231 - Civil Supersonic Aircraft Panel Discussion

Science.gov (United States)

2011-05-24

... awareness of the continuing technological advancements in supersonic aircraft technology aimed at reducing... Wednesday, April 21, 2010, as part of the joint meeting of the 159th Acoustical Society of America and NOISE... advances in supersonic technology, and for the FAA, the National Aeronautics and Space Administration (NASA...

Environmental Assessment for the Beddown of C-17 Aircraft at March Air Reserve Base, California

Science.gov (United States)

2003-02-01

chickens up to ten weeks were not affected by exposure to various sound intensities of reproduced jet aircraft noise (Manci et al. 1988). Pregnancy ...training areas proposed fo.r C-l7 aircraft uti lization include tbe Air Force Plant No. 42 (Palmdale) and Desert Center Zoue, which are located near

Noise enhanced stability effect in a metastable system with two different kinds of time delays and cross-correlated noises

International Nuclear Information System (INIS)

Jia Zhenglin; Mei Dongcheng

2011-01-01

We numerically investigate the influences of the time delay τ simultaneously existing in both the deterministic and fluctuating forces, the time delay τ r existing only in the fluctuating force and the cross-correlation strength λ on the enhancement of the mean first-passage time (MFPT) as a function of the additive D and the multiplicative α noise intensities in a metastable system. The results indicate that both the multiplicative and additive noises can induce the noise-enhanced stability (NES) effect. An increase of λ can enhance or weaken the NES effect induced by the additive noise, depending on the value of τ. However, it weakens the NES effect induced by the multiplicative noise with a suppression of the effect of λ caused by increasing τ. The τ-induced critical behavior on both NES effects can be observed, i.e. an increase of τ can enhance or restrain the NES effects induced by the two kinds of noises. With an increase of λ and τ, MFPT versus D shows a transition from one peak to two peaks and finally one peak, implying the multiple NES effect caused by λ and τ. An increase of τ r can enhance the NES effect induced by the additive noise and weaken the NES effect induced by the multiplicative noise.

Electromagnetic launch systems for civil aircraft assisted take-off

Directory of Open Access Journals (Sweden)

Bertola Luca

2015-12-01

Full Text Available This paper considers the feasibility of different technologies for an electromagnetic launcher to assist civil aircraft take-off. This method is investigated to reduce the power required from the engines during initial acceleration. Assisted launch has the potential of reducing the required runway length, reducing noise near airports and improving overall aircraft efficiency through reducing engine thrust requirements. The research compares two possible linear motor topologies which may be efficaciously used for this application. The comparison is made on results from both analytical and finite element analysis (FEA.

Influence of background noise on the performance in the odor sensitivity task: effects of noise type and extraversion.

Science.gov (United States)

Seo, Han-Seok; Hähner, Antje; Gudziol, Volker; Scheibe, Mandy; Hummel, Thomas

2012-10-01

Recent research demonstrated that background noise relative to silence impaired subjects' performance in a cognitively driven odor discrimination test. The current study aimed to investigate whether the background noise can also modulate performance in an odor sensitivity task that is less cognitively loaded. Previous studies have shown that the effect of background noise on task performance can be different in relation to degree of extraversion and/or type of noise. Accordingly, we wanted to examine whether the influence of background noise on the odor sensitivity task can be altered as a function of the type of background noise (i.e., nonverbal vs. verbal noise) and the degree of extraversion (i.e., introvert vs. extrovert group). Subjects were asked to conduct an odor sensitivity task in the presence of either nonverbal noise (e.g., party sound) or verbal noise (e.g., audio book), or silence. Overall, the subjects' mean performance in the odor sensitivity task was not significantly different across three auditory conditions. However, with regard to the odor sensitivity task, a significant interaction emerged between the type of background noise and the degree of extraversion. Specifically, verbal noise relative to silence significantly impaired or improved the performance of the odor sensitivity task in the introvert or extrovert group, respectively; the differential effect of introversion/extraversion was not observed in the nonverbal noise-induced task performance. In conclusion, our findings provide new empirical evidence that type of background noise and degree of extraversion play an important role in modulating the effect of background noise on subjects' performance in an odor sensitivity task.

Objective measures of listening effort: effects of background noise and noise reduction.

Science.gov (United States)

Sarampalis, Anastasios; Kalluri, Sridhar; Edwards, Brent; Hafter, Ervin

2009-10-01

This work is aimed at addressing a seeming contradiction related to the use of noise-reduction (NR) algorithms in hearing aids. The problem is that although some listeners claim a subjective improvement from NR, it has not been shown to improve speech intelligibility, often even making it worse. To address this, the hypothesis tested here is that the positive effects of NR might be to reduce cognitive effort directed toward speech reception, making it available for other tasks. Normal-hearing individuals participated in 2 dual-task experiments, in which 1 task was to report sentences or words in noise set to various signal-to-noise ratios. Secondary tasks involved either holding words in short-term memory or responding in a complex visual reaction-time task. At low values of signal-to-noise ratio, although NR had no positive effect on speech reception thresholds, it led to better performance on the word-memory task and quicker responses in visual reaction times. Results from both dual tasks support the hypothesis that NR reduces listening effort and frees up cognitive resources for other tasks. Future hearing aid research should incorporate objective measurements of cognitive benefits.

Auditory intensity processing: Effect of MRI background noise.

Science.gov (United States)

Angenstein, Nicole; Stadler, Jörg; Brechmann, André

2016-03-01

Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a rating procedure for low frequency noise : Results of measurements near runways

NARCIS (Netherlands)

Buikema, E.; Vercammen, M.; Ploeg, F. van der; Granneman, J.; Vos, J.

2010-01-01

Recent issues concerning low frequency aircraft noise around airports (groundnoise) and a legal verdict about the application of low frequency noise criteria in the Netherlands have been the motivation to start a research commissioned by the Dutch Ministry of Housing, Spatial Planning and the

Supersonics/Airport Noise Plan: An Evolutionary Roadmap

Science.gov (United States)

Bridges, James

2011-01-01

This presentation discusses the Plan for the Airport Noise Tech Challenge Area of the Supersonics Project. It is given in the context of strategic planning exercises being done in other Projects to show the strategic aspects of the Airport Noise plan rather than detailed task lists. The essence of this strategic view is the decomposition of the research plan by Concept and by Tools. Tools (computational, experimental) is the description of the plan that resources (such as researchers) most readily identify with, while Concepts (here noise reduction technologies or aircraft configurations) is the aspects that project management and outside reviewers most appreciate as deliverables and milestones. By carefully cross-linking these so that Concepts are addressed sequentially (roughly one after another) by researchers developing/applying their Tools simultaneously (in parallel with one another), the researchers can deliver milestones at a reasonable pace while doing the longer-term development that most Tools in the aeroacoustics science require. An example of this simultaneous application of tools was given for the Concept of High Aspect Ratio Nozzles. The presentation concluded with a few ideas on how this strategic view could be applied to the Subsonic Fixed Wing Project's Quiet Aircraft Tech Challenge Area as it works through its current roadmapping exercise.

ICBEN review of research on the biological effects of noise 2011-2014

Science.gov (United States)

Basner, Mathias; Brink, Mark; Bristow, Abigail; de Kluizenaar, Yvonne; Finegold, Lawrence; Hong, Jiyoung; Janssen, Sabine A; Klaeboe, Ronny; Leroux, Tony; Liebl, Andreas; Matsui, Toshihito; Schwela, Dieter; Sliwinska-Kowalska, Mariola; Sörqvist, Patrik

2015-01-01

The mandate of the International Commission on Biological Effects of Noise (ICBEN) is to promote a high level of scientific research concerning all aspects of noise-induced effects on human beings and animals. In this review, ICBEN team chairs and co-chairs summarize relevant findings, publications, developments, and policies related to the biological effects of noise, with a focus on the period 2011-2014 and for the following topics: Noise-induced hearing loss; nonauditory effects of noise; effects of noise on performance and behavior; effects of noise on sleep; community response to noise; and interactions with other agents and contextual factors. Occupational settings and transport have been identified as the most prominent sources of noise that affect health. These reviews demonstrate that noise is a prevalent and often underestimated threat for both auditory and nonauditory health and that strategies for the prevention of noise and its associated negative health consequences are needed to promote public health. PMID:25774609

Social-Ecological Soundscapes: Examining Aircraft-Harvester-Caribou Conflict in Arctic Alaska

Science.gov (United States)

Stinchcomb, Taylor R.

quantify interactions and provide baseline data that may foster mitigation discourses among stakeholders. In Chapter 2, I employed a soundscape-ecology approach to address concerns about aircraft activity expressed by the Alaska Native community of Nuiqsut. Nuiqsut faces the greatest volume of aircraft activity of any community in Arctic Alaska because of its proximity to intensive oil and gas activity. However, information on when and where these aircraft are flying is unavailable to residents, managers, and researchers. I worked closely with Nuiqsut residents to deploy acoustic monitoring systems along important caribou harvest corridors during the peak of caribou harvest, from early June through late August 2016. This method successfully captured aircraft sound and the community embraced my science for addressing local priorities. I found aircraft activity levels near Nuiqsut and surrounding oil developments (12 daily events) to be approximately six times greater than in areas over 30 km from the village (two daily events). Aircraft sound disturbance was 26 times lower in undeveloped areas (Noise Free Interval =13 hrs) than near human development (NFI = 0.5 hrs). My study provided baseline data on aircraft activity and noise levels. My research could be used by stakeholders and managers to develop conflict avoidance agreements and minimize interference with traditional harvest practices. Soundscape methods could be adapted to rural regions across Alaska that may be experiencing conflict with aircraft or other sources of noise that disrupt human-wildlife interactions. By quantifying aircraft activity using a soundscape approach, I demonstrated a novel application of an emerging field in ecology and provided the first scientific data on one dimension of a larger social-ecological system. Future soundscape studies should be integrated with research on both harvester and caribou behaviors to understand how the components within this system are interacting over space and

Nuisance levels of noise effects radiologists' performance

Science.gov (United States)

McEntee, Mark F.; Coffey, Amina; Ryan, John; O'Beirne, Aaron; Toomey, Rachel; Evanoff, Micheal; Manning, David; Brennan, Patrick C.

2010-02-01

This study aimed to measure the sound levels in Irish x-ray departments. The study then established whether these levels of noise have an impact on radiologists performance Noise levels were recorded 10 times within each of 14 environments in 4 hospitals, 11 of which were locations where radiologic images are judged. Thirty chest images were then presented to 26 senior radiologists, who were asked to detect up to three nodular lesions within 30 posteroanterior chest x-ray images in the absence and presence of noise at amplitude demonstrated in the clinical environment. The results demonstrated that noise amplitudes rarely exceeded that encountered with normal conversation with the maximum mean value for an image-viewing environment being 56.1 dB. This level of noise had no impact on the ability of radiologists to identify chest lesions with figure of merits of 0.68, 0.69, and 0.68 with noise and 0.65, 0.68, and 0.67 without noise for chest radiologists, non-chest radiologists, and all radiologists, respectively. the difference in their performance using the DBM MRMC method was significantly better with noise than in the absence of noise at the 90% confidence interval (p=0.077). Further studies are required to establish whether other aspects of diagnosis are impaired such as recall and attention and the effects of more unexpected noise on performance.

Symmetric airfoil geometry effects on leading edge noise.

Science.gov (United States)

Gill, James; Zhang, X; Joseph, P

2013-10-01

Computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. Single frequency harmonic gusts are interacted with various airfoil geometries at zero angle of attack. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and independently for the first time, at higher frequencies than previously used in computational methods. Increases in both leading edge radius and thickness are found to reduce the predicted noise. This noise reduction effect becomes greater with increasing frequency and Mach number. The dominant noise reduction mechanism for airfoils with real geometry is found to be related to the leading edge stagnation region. It is shown that accurate leading edge noise predictions can be made when assuming an inviscid meanflow, but that it is not valid to assume a uniform meanflow. Analytic flat plate predictions are found to over-predict the noise due to a NACA 0002 airfoil by up to 3 dB at high frequencies. The accuracy of analytic flat plate solutions can be expected to decrease with increasing airfoil thickness, leading edge radius, gust frequency, and Mach number.

Aerodynamic Noise An Introduction for Physicists and Engineers

CERN Document Server

Bose, Tarit

2013-01-01

Aerodynamic Noise extensively covers the theoretical basis and mathematical modeling of sound, especially the undesirable sounds produced by aircraft. This noise could come from an aircraft’s engine—propellers, fans, combustion chamber, jets—or the vehicle itself—external surfaces—or from sonic booms. The majority of the sound produced is due to the motion of air and its interaction with solid boundaries, and this is the main discussion of the book. With problem sets at the end of each chapter, Aerodynamic Noise is ideal for graduate students of mechanical and aerospace engineering. It may also be useful for designers of cars, trains, and wind turbines.

Acoustic Characterization and Prediction of Representative, Small-Scale Rotary-Wing Unmanned Aircraft System Components

Science.gov (United States)

Zawodny, Nikolas S.; Boyd, D. Douglas, Jr.; Burley, Casey L.

2016-01-01

In this study, hover performance and acoustic measurements are taken on two different isolated rotors representative of small-scale rotary-wing unmanned aircraft systems (UAS) for a range of rotation rates. Each rotor system consists of two fixed-pitch blades powered by a brushless motor. For nearly the same thrust condition, significant differences in overall sound pressure level (OASPL), up to 8 dB, and directivity were observed between the two rotor systems. Differences are shown to be in part attributed to different rotor tip speeds, along with increased broadband and motor noise levels. In addition to acoustic measurements, aeroacoustic predictions were implemented in order to better understand the noise content of the rotor systems. Numerical aerodynamic predictions were computed using the unsteady Reynoldsaveraged Navier Stokes code OVERFLOW2 on one of the isolated rotors, while analytical predictions were computed using the Propeller Analysis System of the Aircraft NOise Prediction Program (ANOPP-PAS) on the two rotor configurations. Preliminary semi-empirical frequency domain broadband noise predictions were also carried out based on airfoil self-noise theory in a rotational reference frame. The prediction techniques further supported trends identified in the experimental data analysis. The brushless motors were observed to be important noise contributors and warrant further investigation. It is believed that UAS acoustic prediction capabilities must consider both rotor and motor components as part of a combined noise-generating system.

Analysis of Turbofan Design Options for an Advanced Single-Aisle Transport Aircraft

Science.gov (United States)

Guynn, Mark D.; Berton, Jeffrey J.; Fisher, Kenneth L.; Haller, William J.; Tong, Michael T.; Thurman, Douglas R.

2009-01-01

The desire for higher engine efficiency has resulted in the evolution of aircraft gas turbine engines from turbojets, to low bypass ratio, first generation turbofans, to today's high bypass ratio turbofans. It is possible that future designs will continue this trend, leading to very-high or ultra-high bypass ratio (UHB) engines. Although increased bypass ratio has clear benefits in terms of propulsion system metrics such as specific fuel consumption, these benefits may not translate into aircraft system level benefits due to integration penalties. In this study, the design trade space for advanced turbofan engines applied to a single-aisle transport (737/A320 class aircraft) is explored. The benefits of increased bypass ratio and associated enabling technologies such as geared fan drive are found to depend on the primary metrics of interest. For example, bypass ratios at which fuel consumption is minimized may not require geared fan technology. However, geared fan drive does enable higher bypass ratio designs which result in lower noise. Regardless of the engine architecture chosen, the results of this study indicate the potential for the advanced aircraft to realize substantial improvements in fuel efficiency, emissions, and noise compared to the current vehicles in this size class.

THE RELATIONSHIP OF THE GENERAL REACTION SCORE WITH THE NATURAL KILLER CELLS ACTIVITY AMONG WOMEN WITH AIRCRAFT NOISE EXPOSURE IN THE AREA OF ADI SOEMARMO AIRPORT SOLO (Hubungan antara general reaction score dengan aktivitas sel NK pada wanita

Directory of Open Access Journals (Sweden)

Hartono Hartono

2011-07-01

performance. For other effects such as changes in the immune system and birth defects, the evidence is limited.The aims of the research is  to find out the correlation of the general reaction score with The Natural Killer cell activity among women with aircraft noise exposure in the area of Adi Sumarmo Airport Solo.The research findings are expected to contribute to the scientific knowledge development and to give benefits for local government and among people in the area of Adi Sumarmo Airport in preventing the effect of aircraft noise. The research design was an analytical survey with a cross sectional approach, taking place at the Dibal and Gagak Sipat Village, Ngemplak Sub district, Boyolali District. The research was conducted from July 2008 to June 2009. The number of respondens was 39. They were divided into 3 groups; group 1 was exposed to 92.29 dB of noise level (13 respondents; group 2 was exposed to 71.79 dB of noise level (13 respondents; and group 3 was exposed to 52.17 dB of noise level (13 respondents. The samples were taken using simple random sampling. The data were analyzed by Pearson Correlation and Anova followed by Post Hoc Test using LSD test completed with Homogenous Subsets. The Anova test showed that there was significant differences in the general reaction score among all groups (p = 0.000. The Pearson correlation test showed that there was a negative association between the general reaction score with the Natural Killer cells activity (r = - 0.613; p < 0.05.

Noise-Source Separation Using Internal and Far-Field Sensors for a Full-Scale Turbofan Engine

Science.gov (United States)

Hultgren, Lennart S.; Miles, Jeffrey H.

2009-01-01

Noise-source separation techniques for the extraction of the sub-dominant combustion noise from the total noise signatures obtained in static-engine tests are described. Three methods are applied to data from a static, full-scale engine test. Both 1/3-octave and narrow-band results are discussed. The results are used to assess the combustion-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP). A new additional phase-angle-based discriminator for the three-signal method is also introduced.

Advanced Propulsion System Studies for General Aviation Aircraft

Science.gov (United States)

Eisenberg, Joseph D. (Technical Monitor); German, Jon

2003-01-01

This final report addresses the following topics: Market Impact Analysis (1) assessment of general aviation, including commuter/regional, aircraft market impact due to incorporation of advanced technology propulsion system on acquisition and operating costs, job creation and/or manpower demand, and future fleet size; (2) selecting an aircraft and engine for the study by focusing on the next generation 19-passenger commuter and the Williams International FJ44 turbofan engine growth. Propulsion System Analysis Conducted mission analysis studies and engine cycle analysis to define a new commuter mission and required engine performance, define acquisition and operating costs and, select engine configuration and initiated preliminary design for hardware modifications required. Propulsion System Benefits (1) assessed and defined engine emissions improvements, (2) assessed and defined noise reduction potential and, (3) conducted a cost analysis impact study. Review of Relevant NASA Programs Conducted literature searches using NERAC and NASA RECON services for related technology in the emissions and acoustics area. Preliminary Technology Development Plans Defined plan to incorporate technology improvements for an FJ44-2 growth engine in performance, emissions, and noise suppression.

The impact of different background noises on the Production Effect.

Science.gov (United States)

Mama, Yaniv; Fostick, Leah; Icht, Michal

2018-04-01

The presence of background noise has been previously shown to disrupt cognitive performance, especially memory. The amount of interference is derived from the acoustic characteristics of the noise; energetic vs. informational, steady-state vs. fluctuating. However, the literature is inconsistent concerning the effects of different types of noise on long-term memory free recall. In the present study, we tested the impact of different noises on recall of items that were learned under two conditions - silent or aloud reading, a Production Effect (PE) paradigm. As the PE represents enhanced memory for words read aloud relative to words read silently during study, we focused on the effect of noise on this robust memory phenomenon. The results showed that (a) steady-state energetic noise did not affect memory, with a recall advantage for aloud words (PE), comparable to a no-noise condition, (b) fluctuating-energetic noise and fluctuating-informational (eight-talkers babble) noise eliminated the PE, with similar recall for aloud and silent items. These results are discussed in light of their theoretical implications, stressing the role of attention in the PE. Ecological implications regarding studying in noisy environments are suggested. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of industrial noise on wildlife : issues and challenges in Alberta

Energy Technology Data Exchange (ETDEWEB)

Burke, D.; Lapka, S. [Alberta Energy and Utilities Board, Calgary, AB (Canada)

2007-07-01

The effects of noise from industrial activities on wildlife was examined with particular reference to the potential impacts of noise on caribou and grizzly bears from the Mackenzie Gas pipeline project. In Alberta, environmental noise requirements for oil and gas production facilities are outlined in the Alberta Energy and Utilities Board (EUB) Noise Control Directive 038. The requirements provide protection for human receptors, but not for wildlife. In order to ensure accurate assessments of the effects that industrial noise is having on wildlife, appropriate study methods must be developed to identify, quantify, and assess wildlife responses to noise. Without this knowledge, noise level thresholds for wildlife species cannot be established. A literature review was presented to demonstrate the range of published information on noise effects on wildlife and to highlight information that is relevant for the development of noise criteria for wildlife. It was concluded that wildlife noise thresholds are unknown, evidence for habituation to industrial facilities is limited, and long-term effects are generally unknown. Preliminary studies do not show any clear indication that observed reactions of wild animals are in response to noise. As such, development of regulatory criteria for wildlife noise control is not recommended at this time. The EUB will continue to keep up to date in wildlife related noise issues and will maintain the existing philosophy to limit noise to 5dB above ambient and to control dBA levels at 1500 m from facility fence lines. 57 refs., 1 fig.

Random effects model for the reliability management of modules of a fighter aircraft

Energy Technology Data Exchange (ETDEWEB)

Sohn, So Young [Department of Computer Science and Industrial Systems Engineering, Yonsei University, Shinchondong 134, Seoul 120-749 (Korea, Republic of)]. E-mail: sohns@yonsei.ac.kr; Yoon, Kyung Bok [Department of Computer Science and Industrial Systems Engineering, Yonsei University, Shinchondong 134, Seoul 120-749 (Korea, Republic of)]. E-mail: ykb@yonsei.ac.kr; Chang, In Sang [Department of Computer Science and Industrial Systems Engineering, Yonsei University, Shinchondong 134, Seoul 120-749 (Korea, Republic of)]. E-mail: isjang@yonsei.ac.kr

2006-04-15

The operational availability of fighter aircrafts plays an important role in the national defense. Low operational availability of fighter aircrafts can cause many problems and ROKA (Republic of Korea Airforce) needs proper strategies to improve the current practice of reliability management by accurately forecasting both MTBF (mean time between failure) and MTTR (mean time to repair). In this paper, we develop a random effects model to forecast both MTBF and MTTR of installed modules of fighter aircrafts based on their characteristics and operational conditions. Advantage of using such a random effects model is the ability of accommodating not only the individual characteristics of each module and operational conditions but also the uncertainty caused by random error that cannot be explained by them. Our study is expected to contribute to ROKA in improving operational availability of fighter aircrafts and establishing effective logistics management.

Detection of aeroacoustic sound sources on aircraft and wind turbines

NARCIS (Netherlands)

Oerlemans, Stefan

2009-01-01

This thesis deals with the detection of aeroacoustic sound sources on aircraft and wind turbines using phased microphone arrays. First, the reliability of the array technique is assessed using airframe noise measurements in open and closed wind tunnels. It is demonstrated that quantitative acoustic

Effect of Correlated Noises in a Genetic Model

International Nuclear Information System (INIS)

Li, Zhang; Li, Cao

2010-01-01

The Stratonovich stochastic differential equation is used to analyze genotype selection in the presence of correlated Gaussian white noises. We study the steady state properties of the genotype selection and discuss the effects of the correlated noises. It is found that the degree of correlation of the noises can be used to select one type of genes from another type of mixing genes. The strong selection of genes caused by a large value of multiplicative noise intensity can be weakened by the intensive negative correlation. (general)

Noise pollution has limited effects on nocturnal vigilance in peahens

Directory of Open Access Journals (Sweden)

Jessica L. Yorzinski

2016-09-01

Full Text Available Natural environments are increasingly exposed to high levels of noise pollution. Noise pollution can alter the behavior of animals but we know little about its effects on antipredator behavior. We therefore investigated the impact of noise pollution on vigilance behavior and roost selection in an avian species, peafowl (Pavo cristatus, that inhabits urban environments. Captive peahens were exposed to noise pollution at night and their vigilance levels and roost selections were monitored. The vigilance levels of peahens were unaffected by exposure to noise pollution within trials. Furthermore, the peahens exhibited no preference for roosting farther or closer to noise pollution. Interestingly, predators often avoided the experimental area during nights with noise pollution, which could explain why vigilance rates were higher overall during control compared to noise trials. The results suggest that peahens’ perception of risk is not drastically impacted by noise pollution but longer-term studies will be necessary to assess any chronic effects.

Noise pollution has limited effects on nocturnal vigilance in peahens.

Science.gov (United States)

Yorzinski, Jessica L; Hermann, Fredrick S

2016-01-01

Natural environments are increasingly exposed to high levels of noise pollution. Noise pollution can alter the behavior of animals but we know little about its effects on antipredator behavior. We therefore investigated the impact of noise pollution on vigilance behavior and roost selection in an avian species, peafowl ( Pavo cristatus ), that inhabits urban environments. Captive peahens were exposed to noise pollution at night and their vigilance levels and roost selections were monitored. The vigilance levels of peahens were unaffected by exposure to noise pollution within trials. Furthermore, the peahens exhibited no preference for roosting farther or closer to noise pollution. Interestingly, predators often avoided the experimental area during nights with noise pollution, which could explain why vigilance rates were higher overall during control compared to noise trials. The results suggest that peahens' perception of risk is not drastically impacted by noise pollution but longer-term studies will be necessary to assess any chronic effects.

Effects of cosmic radiation on devices and embedded systems in aircrafts

Energy Technology Data Exchange (ETDEWEB)

Prado, Adriane C.M.; Federico, Claudio A.; Pereira Junior, Evaldo C.F.; Goncalez, Odair L., E-mail: claudiofederico@ieav.cta.br, E-mail: odairlelisgoncalez@gmail.com, E-mail: adriane.acm@hotmail.com, E-mail: evaldocarlosjr@gmail.com [Instituto de Estudos Avancados (IEAV/DCTA), Sao Jose dos Campos, SP (Brazil)

2013-07-01

Modern avionics systems use new electronic technologies devices that, due to their high degree of sophistication and miniaturization, are more susceptible to the effects of ionizing radiation, particularly the effect called 'Single Event Effect' (SEE) produced by neutron. Studies regarding the effects of radiation on electronic systems for space applications, such as satellites and orbital stations, have already been in progress for several years. However, tolerance requirements and specific studies, focusing on testing dedicated to avionics, have caused concern and gained importance in the last decade as a result of the accidents attributed to SEE in aircraft. Due to the development of a higher ceiling, an increase in airflow and a greater autonomy of certain aircrafts, the problem regarding the control of ionizing radiation dose received by the pilots, the crew and sensitive equipment became important in the areas of occupational health, radiation protection and flight safety. This paper presents an overview of the effects of ionizing radiation on devices and embedded systems in aircrafts, identifying and classifying these effects in relation to their potential risks in each device class. The assessment of these effects in avionics is a very important and emerging issue nowadays, which is being discussed by groups of the international scientific community; however, in South America, groups working in this area are still unknown. Consequently, this work is a great contribution and significantly valuable to the area of aeronautical engineering and flight safety associated to the effects of radiation on electronic components embedded in aircraft. (author)

Effects of cosmic radiation on devices and embedded systems in aircrafts

International Nuclear Information System (INIS)

Prado, Adriane C.M.; Federico, Claudio A.; Pereira Junior, Evaldo C.F.; Goncalez, Odair L.

2013-01-01

Modern avionics systems use new electronic technologies devices that, due to their high degree of sophistication and miniaturization, are more susceptible to the effects of ionizing radiation, particularly the effect called 'Single Event Effect' (SEE) produced by neutron. Studies regarding the effects of radiation on electronic systems for space applications, such as satellites and orbital stations, have already been in progress for several years. However, tolerance requirements and specific studies, focusing on testing dedicated to avionics, have caused concern and gained importance in the last decade as a result of the accidents attributed to SEE in aircraft. Due to the development of a higher ceiling, an increase in airflow and a greater autonomy of certain aircrafts, the problem regarding the control of ionizing radiation dose received by the pilots, the crew and sensitive equipment became important in the areas of occupational health, radiation protection and flight safety. This paper presents an overview of the effects of ionizing radiation on devices and embedded systems in aircrafts, identifying and classifying these effects in relation to their potential risks in each device class. The assessment of these effects in avionics is a very important and emerging issue nowadays, which is being discussed by groups of the international scientific community; however, in South America, groups working in this area are still unknown. Consequently, this work is a great contribution and significantly valuable to the area of aeronautical engineering and flight safety associated to the effects of radiation on electronic components embedded in aircraft. (author)

Aircraft Engine Technology for Green Aviation to Reduce Fuel Burn

Science.gov (United States)

Hughes, Christopher E.; VanZante, Dale E.; Heidmann, James D.

2013-01-01

The NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project and Integrated Systems Research Program Environmentally Responsible Aviation Project in the Aeronautics Research Mission Directorate are conducting research on advanced aircraft technology to address the environmental goals of reducing fuel burn, noise and NOx emissions for aircraft in 2020 and beyond. Both Projects, in collaborative partnerships with U.S. Industry, Academia, and other Government Agencies, have made significant progress toward reaching the N+2 (2020) and N+3 (beyond 2025) installed fuel burn goals by fundamental aircraft engine technology development, subscale component experimental investigations, full scale integrated systems validation testing, and development validation of state of the art computation design and analysis codes. Specific areas of propulsion technology research are discussed and progress to date.

Effect of flow parameters on flare stack generator noise

International Nuclear Information System (INIS)

Dinn, T.S.

1998-01-01

The SoundPLAN Computer Noise Model was used to determine the general effect of flare noise in a community adjacent to a petrochemical plant. Tests were conducted to determine the effect of process flow conditions and the pulsating flame on the flare stack generator noise from both a refinery flare and process flare. Flaring under normal plant operations, the flaring of fuel gas and the flaring of hydrogen were the three conditions that were tested. It was shown that the steam flow rate was the determining factor in the flare stack generated noise. Variations in the water seal level in the flare line surge tank increased or decreased the gas flowrate, which resulted in a pulsating flame. The period and amplitude of the pulsating noise from the flare stacks was determined by measuring several parameters. Flare stack noise oscillations were found to be greater for the process flare than for the refinery flare stack. It was suggested that minimizing the amount of steam fed to the flare and improving the burner design would minimize noise. 2 tabs., 6 figs

Detection of aeroacoustic sound sources on aircraft and wind turbines

International Nuclear Information System (INIS)

Oerlemans, S.

2009-01-01

This thesis deals with the detection of aeroacoustic sound sources on aircraft and wind turbines using phased microphone arrays. First, the reliability of the array technique is assessed using airframe noise measurements in open and closed wind tunnels. It is demonstrated that quantitative acoustic measurements are possible in both wind tunnels. Then, the array technique is applied to characterize the noise sources on two modern large wind turbines. It is shown that practically all noise emitted to the ground is produced by the outer part of the blades during their downward movement. This asymmetric source pattern, which causes the typical swishing noise during the passage of the blades, can be explained by trailing edge noise directivity and convective amplification. Next, a semi-empirical prediction method is developed for the noise from large wind turbines. The prediction code is successfully validated against the experimental results, not only with regard to sound levels, spectra, and directivity, but also with regard to the noise source distribution in the rotor plane and the temporal variation in sound level (swish). The validated prediction method is then applied to calculate wind turbine noise footprints, which show that large swish amplitudes can occur even at large distance. The influence of airfoil shape on blade noise is investigated through acoustic wind tunnel tests on a series of wind turbine airfoils. Measurements are carried out at various wind speeds and angles of attack, with and without upstream turbulence and boundary layer tripping. The speed dependence, directivity, and tonal behaviour are determined for both trailing edge noise and inflow turbulence noise. Finally, two noise reduction concepts are tested on a large wind turbine: acoustically optimized airfoils and trailing edge serrations. Both blade modifications yield a significant trailing edge noise reduction at low frequencies, but also cause increased tip noise at high frequencies

Reduction of Background Noise in the NASA Ames 40- by 80-Foot Wind Tunnel

Science.gov (United States)

Jaeger, Stephen M.; Allen, Christopher S.; Soderman, Paul T.; Olson, Larry E. (Technical Monitor)

1995-01-01

Background noise in both open-jet and closed wind tunnels adversely affects the signal-to-noise ratio of acoustic measurements. To measure the noise of increasingly quieter aircraft models, the background noise will have to be reduced by physical means or through signal processing. In a closed wind tunnel, such as the NASA Ames 40- by 80- Foot Wind Tunnel, the principle background noise sources can be classified as: (1) fan drive noise; (2) microphone self-noise; (3) aerodynamically induced noise from test-dependent hardware such as model struts and junctions; and (4) noise from the test section walls and vane set. This paper describes the steps taken to minimize the influence of each of these background noise sources in the 40 x 80.

Active Structural Acoustic Control in an Original A400M Aircraft Structure

International Nuclear Information System (INIS)

Koehne, C; Sachau, D; Renger, K

2016-01-01

Low frequency noise has always been a challenge in propeller driven aircraft. At low frequencies passive noise treatments are not as efficient as active noise reduction systems. The Helmut-Schmidt-University has built up a full-scale test rig with an original A400M aircraft structure. This provides a good opportunity to develop and test active noise reduction systems in a realistic environment. The currently installed system consists of mechanical actuators and acoustical sensors. The actuators are called TVAs (Tuneable Vibration Absorber) and contain two spring-mass systems whose natural frequencies are adjusted to the BPFs (Blade Passage Frequency) of the propellers. The TVAs are mounted to the frames and the force direction is normal to the skin. The sensors are condenser microphones which are attached to the primary structure of the airframe. The TVAs are equipped with signal processing devices. These components carry out Fourier transforms and signal amplification for the sensor data and actuator signals. The communication between the TVAs and the central control unit is implemented by the CAN Bus protocol and mainly consists of complex coefficients for the sensor and actuator data. This paper describes the basic structure of the system, the hardware set-up and function tests of the controller. (paper)

Active Structural Acoustic Control in an Original A400M Aircraft Structure

Science.gov (United States)

Koehne, C.; Sachau, D.; Renger, K.

2016-09-01

Low frequency noise has always been a challenge in propeller driven aircraft. At low frequencies passive noise treatments are not as efficient as active noise reduction systems. The Helmut-Schmidt-University has built up a full-scale test rig with an original A400M aircraft structure. This provides a good opportunity to develop and test active noise reduction systems in a realistic environment. The currently installed system consists of mechanical actuators and acoustical sensors. The actuators are called TVAs (Tuneable Vibration Absorber) and contain two spring-mass systems whose natural frequencies are adjusted to the BPFs (Blade Passage Frequency) of the propellers. The TVAs are mounted to the frames and the force direction is normal to the skin. The sensors are condenser microphones which are attached to the primary structure of the airframe. The TVAs are equipped with signal processing devices. These components carry out Fourier transforms and signal amplification for the sensor data and actuator signals. The communication between the TVAs and the central control unit is implemented by the CAN Bus protocol and mainly consists of complex coefficients for the sensor and actuator data. This paper describes the basic structure of the system, the hardware set-up and function tests of the controller.

Numerical Investigation on Vortex-Structure Interaction Generating Aerodynamic Noises for Rod-Airfoil Models

Directory of Open Access Journals (Sweden)

FeiFei Liu

2017-01-01

Full Text Available In past several decades, vortex-structure interaction generated aerodynamic noise became one of the main concerns in aircraft design. In order to understand the mechanism, the acoustic analogy method combined with the RANS-based nonlinear acoustics solver (NLAS is investigated. The numerical method is firstly evaluated by the experiment data of the classic rod-airfoil model. Compared with the traditional analogy methods, the RANS/NLAS can capture the nonlinear aerodynamic noise more accurately with lower gird requirements. Then different rod-airfoil configurations were simulated to investigate the aeroacoustic interaction effects. The numerical results are in good agreement with those of the earlier experimental research. It is found that the vortex-shedding crash to the airfoil is the main reason for the noise generation which is dependent on the configurations, distance, and flow conditions.

Differential effects of white noise in cognitive and perceptual tasks

Directory of Open Access Journals (Sweden)

Nora Alicia Herweg

2015-11-01

Full Text Available Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy when presented during the maintenance period (experiment 1-3. In a reward based long-term memory task, white noise accelerated perceptual judgments for scene images during encoding but left subsequent recognition memory unaffected (experiment 4. In a modified Posner task (experiment 5, the benefit due to white noise in attentional orienting correlated weakly with reward dependence, a personality trait that has been associated with the dopaminergic system. These results suggest that white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation.

Differential effects of white noise in cognitive and perceptual tasks.

Science.gov (United States)

Herweg, Nora A; Bunzeck, Nico

2015-01-01

Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy when presented during the maintenance period (Experiments 1-3). In a reward based long-term memory task, white noise accelerated perceptual judgments for scene images during encoding but left subsequent recognition memory unaffected (Experiment 4). In a modified Posner task (Experiment 5), the benefit due to white noise in attentional orienting correlated weakly with reward dependence, a personality trait that has been associated with the dopaminergic system. These results suggest that white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation.

Cardiovascular effects of environmental noise: Research in Austria

Directory of Open Access Journals (Sweden)

Peter Lercher

2011-01-01

Full Text Available Cardiovascular effects of noise rank second in terms of disability-adjusted life year (DALYs after annoyance. Although research during the past decade has consolidated the available data base, the most recent meta-analysis still shows wide confidence intervals - indicating imprecise information for public health risk assessment. The alpine area of Tyrol in the Austrian part of the Alps has experienced a massive increase in car and heavy goods traffic (road and rail during the last 35 years. Over the past 25 years small-, middle-, and large-sized epidemiological health surveys have been conducted - mostly within the framework of environmental health impact assessments. By design, these studies have emphasized a contextually driven environmental stress perspective, where the adverse health effects on account of noise are studied in a broader framework of environmental health, susceptibility, and coping. Furthermore, innovative exposure assessment strategies have been implemented. This article reviews the existing knowledge from these studies over time, and presents the exposure-response curves, with and without interaction assessment, based on standardized re-analyses and discusses it in the light of past and current cardiovascular noise effects research. The findings support relevant moderation by age, gender, and family history in nearly all studies and suggest a strong need for consideration of non-linearity in the exposure-response analyses. On the other hand, air pollution has not played a relevant role as a moderator in the noise-hypertension or the noise-angina pectoris relationship. Finally, different noise modeling procedures can introduce variations in the exposure response curves, with substantive consequences for public health risk assessment of noise exposure.

Enhanced Fan Noise Modeling for Turbofan Engines

Science.gov (United States)

Krejsa, Eugene A.; Stone, James R.

2014-01-01

This report describes work by consultants to Diversitech Inc. for the NASA Glenn Research Center (GRC) to revise the fan noise prediction procedure based on fan noise data obtained in the 9- by 15 Foot Low-Speed Wind Tunnel at GRC. The purpose of this task is to begin development of an enhanced, analytical, more physics-based, fan noise prediction method applicable to commercial turbofan propulsion systems. The method is to be suitable for programming into a computational model for eventual incorporation into NASA's current aircraft system noise prediction computer codes. The scope of this task is in alignment with the mission of the Propulsion 21 research effort conducted by the coalition of NASA, state government, industry, and academia to develop aeropropulsion technologies. A model for fan noise prediction was developed based on measured noise levels for the R4 rotor with several outlet guide vane variations and three fan exhaust areas. The model predicts the complete fan noise spectrum, including broadband noise, tones, and for supersonic tip speeds, combination tones. Both spectra and directivity are predicted. Good agreement with data was achieved for all fan geometries. Comparisons with data from a second fan, the ADP fan, also showed good agreement.

Effects of Colored Noise on Stochastic Resonance in Sensory Neurons

International Nuclear Information System (INIS)

Nozaki, D.; Mar, D.J.; Collins, J.J.; Grigg, P.

1999-01-01

Noise can assist neurons in the detection of weak signals via a mechanism known as stochastic resonance (SR). We demonstrate experimentally that SR-type effects can be obtained in rat sensory neurons with white noise, 1/f noise, or 1/f 2 noise. For low-frequency input noise, we show that the optimal noise intensity is the lowest and the output signal-to-noise ratio the highest for conventional white noise. We also show that under certain circumstances, 1/f noise can be better than white noise for enhancing the response of a neuron to a weak signal. We present a theory to account for these results and discuss the biological implications of 1/f noise. copyright 1999 The American Physical Society

Fundamental and applied research on core engine/combustion noise of aircraft engines

Science.gov (United States)

Plett, E. G.; Leshner, M. D.; Summerfield, M.

1974-01-01

Some results of a study of the importance of geometrical features of the combustor to combustion roughness and resulting noise are presented. Comparison is made among a perforated can flame holder, a plane slotted flame holder and a plane slotted flame holder which introduces two counter swirling streams. The latter is found to permit the most stable, quiet combustion. Crosscorrelations between the time derivative of chamber pressure fluctuations and far field noise are found to be stronger than between the far field noise and the direct chamber pressure signal. Temperature fluctuations in the combustor nozzle are also found to have a reasonably strong crosscorrelation with far field sound.

Effect of noise on humans; Effet du bruit sur l'homme

Energy Technology Data Exchange (ETDEWEB)

Jouhaneau, J. [Conservatoire National des Arts et Metiers, CNAM, 75 - Paris (France)

2001-07-01

Noise remains one of the most badly known pollution source with respect to its effects on mankind and to its economical and social impacts. This bad knowledge is the consequence of the difficulty to measure the real short, average and long-term consequences of the noise aggression on living organisms which can adapt and hide some part of these effects. Also, noise comprises several subjective components and can be felt differently from one person to the other with different reactions sometimes contradictory or ambiguous. Content: 1 - definitions of noise; 2 - auditive effects of noise (discomfort, loss of audition); 3 - non-auditive effects (physiological stress, physiological disturbances); 4 - other disturbances (effects on sleep, effects on performance); 5 - theories about the mechanisms of noise action. (J.S.)

Reduction of broadband noise in vehicles by means of active feedforward control

OpenAIRE

Misol, Malte; Haase, Thomas; Monner, Hans Peter

2015-01-01

Broadband noise in a vehicle’s interior is an important issue because of its negative impact on the passengersʼ comfort and wellbeing. The perception of this broadband noise can increase due to the use of new, less noisy drive concepts and the accompanying loss of masking noise compo-nents. This contribution focuses on the reduction of the transmission of external broadband distur-bances through lightweight panel structures (e.g. a car’s roof liner or an aircraft sidewall panel) by means of a...

Neurally based measurement and evaluation of environmental noise

CERN Document Server

Soeta, Yoshiharu

2015-01-01

This book deals with methods of measurement and evaluation of environmental noise based on an auditory neural and brain-oriented model. The model consists of the autocorrelation function (ACF) and the interaural cross-correlation function (IACF) mechanisms for signals arriving at the two ear entrances. Even when the sound pressure level of a noise is only about 35 dBA, people may feel annoyed due to the aspects of sound quality. These aspects can be formulated by the factors extracted from the ACF and IACF. Several examples of measuring environmental noise—from outdoor noise such as that of aircraft, traffic, and trains, and indoor noise such as caused by floor impact, toilets, and air-conditioning—are demonstrated. According to the noise measurement and evaluation, applications for sound design are discussed. This book provides an excellent resource for students, researchers, and practitioners in a wide range of fields, such as the automotive, railway, and electronics industries, and soundscape, architec...

[Noise Effects on Mental Health: a review of literature].

Science.gov (United States)

Makopa Kenda, Israel; Agoub, Mohamed; Ahami, A O T

2014-01-01

Any human activity generates noise. It is considered as a risk factor for people's health. The present review of literature has assessed the impact of noise on mental health; it is summarized into four points: objective, methods, results and conclusion. The main objective of this study is to expose the actual knowledge state of noise effects on mental health after overview and critical analysis of literature to identify the acquired and shortcomings, to reflect on research direction in terms of noise pollution in the future. The literature review was conducted based on: research of keys words in articles published, research of the number of quotations of articles in Journal Citation Reports (JCR), published in web of science, research of impact factor of journals. One hundred articles were selected, after analyzing contents, items were classified into: fundamental studies (25%), experimental studies (50%), and epidemiological studies (25%). The fundamental studies have verified the hypothesis according to which noise generates stress. Researchers have dosed hormones of stress in plasma, urine and saliva in individuals exposed to noise of different decibels. The results found were unanimous: The rates of stress hormones found, were significantly high in three liquids. This means that noise causes stress. For experimental studies, researchers have experienced the role of noise on memory, attention and performance. Human subjects were exposed to different decibels to assess level of disruption to their memory, attention, and performance. The results revealed that noise disturbs memory, distracts attention and decreases performance. Experimental studies are the most abundant and constitute 50% of the current literature review.The epidemiological studies have evaluated the intellectual performance of students in schools located in noisy environments and residents in areas surrounding airports, railways and highways. RESULTS have revealed that students in schools located

Beam-beam effects under the influence of external noise

International Nuclear Information System (INIS)

Ohmi, K

2014-01-01

Fast external noise, which gives fluctuation into the beam orbit, is discussed in connection with beam-beam effects. Phase noise from crab cavities and detection devices (position monitor) and kicker noise from the bunch by bunch feedback system are the sources. Beam-beam collisions with fast orbit fluctuations with turn by turn or multi-turn correlations, cause emittance growth and luminosity degradation. We discuss the tolerance of the noise amplitude for LHC and HL-LHC

Health effects related to wind turbine noise exposure: a systematic review.

Science.gov (United States)

Schmidt, Jesper Hvass; Klokker, Mads

2014-01-01

Wind turbine noise exposure and suspected health-related effects thereof have attracted substantial attention. Various symptoms such as sleep-related problems, headache, tinnitus and vertigo have been described by subjects suspected of having been exposed to wind turbine noise. This review was conducted systematically with the purpose of identifying any reported associations between wind turbine noise exposure and suspected health-related effects. A search of the scientific literature concerning the health-related effects of wind turbine noise was conducted on PubMed, Web of Science, Google Scholar and various other Internet sources. All studies investigating suspected health-related outcomes associated with wind turbine noise exposure were included. Wind turbines emit noise, including low-frequency noise, which decreases incrementally with increases in distance from the wind turbines. Likewise, evidence of a dose-response relationship between wind turbine noise linked to noise annoyance, sleep disturbance and possibly even psychological distress was present in the literature. Currently, there is no further existing statistically-significant evidence indicating any association between wind turbine noise exposure and tinnitus, hearing loss, vertigo or headache. Selection bias and information bias of differing magnitudes were found to be present in all current studies investigating wind turbine noise exposure and adverse health effects. Only articles published in English, German or Scandinavian languages were reviewed. Exposure to wind turbines does seem to increase the risk of annoyance and self-reported sleep disturbance in a dose-response relationship. There appears, though, to be a tolerable level of around LAeq of 35 dB. Of the many other claimed health effects of wind turbine noise exposure reported in the literature, however, no conclusive evidence could be found. Future studies should focus on investigations aimed at objectively demonstrating whether or not

Effects of Aircraft Noise and Sonic Booms on Domestic Animals and Wildlife: A Literature Synthesis

Science.gov (United States)

1988-06-01

auditory thresholds of Suffolk ewe lambs (Ames and Arehart 1972; Ames 1978) and cattle (Ames 1974). The threshold curve of the lambs declined...in castrated male pigs exposed to 93-dB (un- specified frequency) continuous noise over several days (Dufour 1980). Excess aldosterone may be induced...34 intake, and behavioral activity of ponies and beef cattle . Pages 170-175 in Proc. Int. Livest. Environ. Symp., University of Nebraska, Lincoln. Am. Soc

NASA Electric Aircraft Test Bed (NEAT) Development Plan - Design, Fabrication, Installation

Science.gov (United States)

Dyson, Rodger W.

2016-01-01

As large airline companies compete to reduce emissions, fuel, noise, and maintenance costs, it is expected that more of their aircraft systems will shift from using turbofan propulsion, pneumatic bleed power, and hydraulic actuation, to instead using electrical motor propulsion, generator power, and electrical actuation. This requires new flight-weight and flight-efficient powertrain components, fault tolerant power management, and electromagnetic interference mitigation technologies. Moreover, initial studies indicate some combination of ambient and cryogenic thermal management and relatively high bus voltages when compared to state of practice will be required to achieve a net system benefit. Developing all these powertrain technologies within a realistic aircraft architectural geometry and under realistic operational conditions requires a unique electric aircraft testbed. This report will summarize existing testbed capabilities located in the U.S. and details the development of a unique complementary testbed that industry and government can utilize to further mature electric aircraft technologies.

Acoustic effects of oil-production activities on bowhead and white whales visible during spring migration near Pt. Barrow, Alaska-1990 phase: sound propagation and whale responses to playbacks of continuous drilling noise from an ice platform, as studied in pack ice conditions. Final report

International Nuclear Information System (INIS)

Richardson, W.J.; Greene, C.R.; Koski, W.R.; Smultea, M.A.; Cameron, G.

1991-10-01

The report concerns the effects of underwater noise from simulated oil production operations on the movements and behavior of bowhead and white whales migrating around northern Alaska in spring. An underwater sound projector suspended from pack ice was used to introduce recorded drilling noise and other test sounds into leads through the pack ice. These sounds were received and measured at various distances to determine the rate of sound attenuation with distance and frequency. The movements and behavior of bowhead and white whales approaching the operating projector were studied by aircraft- and ice-based observers. Some individuals of both species were observed to approach well within the ensonified area. However, behavioral changes and avoidance reactions were evident when the received sound level became sufficiently high. Reactions to aircraft are also discussed

Understanding noise suppression in heterojunction field-effect transistors

International Nuclear Information System (INIS)

Green, F.

1996-01-01

Full text: The enhanced transport properties displayed by quantum-well-confined, two-dimensional, electron systems underpin the success of heterojunction, field-effect transistors. At cryogenic temperatures, these devices exhibit impressive mobilities and, as a result, high signal gain and low noise. Conventional wisdom has it that the same favourable conditions also hold for normal room-temperature operation. In that case, however, high mobilities are precluded by abundant electron-phonon scattering. Our recent study of nonequilibrium current noise shows that quantum confinement, not high mobility, is the principal source of noise in these devices; this opens up new and exciting opportunities in low-noise transistor design. As trends in millimetre-wave technology push frequencies beyond 100 GHz, it is essential to develop a genuine understanding of noise processes in heterojunction devices

Field-Deployable Acoustic Digital Systems for Noise Measurement

Science.gov (United States)

Shams, Qamar A.; Wright, Kenneth D.; Lunsford, Charles B.; Smith, Charlie D.

2000-01-01

Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.

Concorde noise-induced building vibrations: International Airport Dulles. [studies by Langley Research Center

Science.gov (United States)

Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Finley, T. D.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

1977-01-01

A series of studies were conducted to assess the noise-induced building vibrations associated with Concorde operations. The vibration levels of windows, walls, and floors were measured along with the associated noise levels of Concorde, subsonic aircraft and some nonaircraft events. Test sites included Sully Plantation which is adjacent to Dulles International Airport and three residential homes located in Montgomery County, Maryland. The measured vibration response levels due to Concorde operations were found to be: (1) higher than the levels due to other aircraft, (2) less than the levels due to certain household events which involve direct impulsive loading such as door and window closing, (3) less than criteria levels for building damage, and (4) comparable to levels which are perceptible to people.

Subsonic Ultra Green Aircraft Research

Science.gov (United States)

Bradley, Marty K.; Droney, Christopher K.

2011-01-01

This Final Report summarizes the work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team in Phase 1, which includes the time period of October 2008 through March 2010. The team consisted of Boeing Research and Technology, Boeing Commercial Airplanes, General Electric, and Georgia Tech. The team completed the development of a comprehensive future scenario for world-wide commercial aviation, selected baseline and advanced configurations for detailed study, generated technology suites for each configuration, conducted detailed performance analysis, calculated noise and emissions, assessed technology risks, and developed technology roadmaps. Five concepts were evaluated in detail: 2008 baseline, N+3 reference, N+3 high span strut braced wing, N+3 gas turbine battery electric concept, and N+3 hybrid wing body. A wide portfolio of technologies was identified to address the NASA N+3 goals. Significant improvements in air traffic management, aerodynamics, materials and structures, aircraft systems, propulsion, and acoustics are needed. Recommendations for Phase 2 concept and technology projects have been identified.

Active Control of Fan Noise-Feasibility Study. Volume 2: Canceling Noise Source-Design of an Acoustic Plate Radiator Using Piezoceramic Actuators

Science.gov (United States)

Pla, F. G.; Rajiyah, H.

1995-01-01

The feasibility of using acoustic plate radiators powered by piezoceramic thin sheets as canceling sources for active control of aircraft engine fan noise is demonstrated. Analytical and numerical models of actuated beams and plates are developed and validated. An optimization study is performed to identify the optimum combination of design parameters that maximizes the plate volume velocity for a given resonance frequency. Fifteen plates with various plate and actuator sizes, thicknesses, and bonding layers were fabricated and tested using results from the optimization study. A maximum equivalent piston displacement of 0.39 mm was achieved with the optimized plate samples tested with only one actuator powered, corresponding to a plate deflection at the center of over 1 millimeter. This is very close to the deflection required for a full size engine application and represents a 160-fold improvement over previous work. Experimental results further show that performance is limited by the critical stress of the piezoceramic actuator and bonding layer rather than by the maximum moment available from the actuator. Design enhancements are described in detail that will lead to a flight-worthy acoustic plate radiator by minimizing actuator tensile stresses and reducing nonlinear effects. Finally, several adaptive tuning methods designed to increase the bandwidth of acoustic plate radiators are analyzed including passive, active, and semi-active approaches. The back chamber pressurization and volume variation methods are investigated experimentally and shown to be simple and effective ways to obtain substantial control over the resonance frequency of a plate radiator. This study shows that piezoceramic-based plate radiators can be a viable acoustic source for active control of aircraft engine fan noise.

Health Effects Related to Wind Turbine Noise Exposure

DEFF Research Database (Denmark)

Schmidt, Jesper Hvass; Klokker, Mads

2014-01-01

BACKGROUND: Wind turbine noise exposure and suspected health-related effects thereof have attracted substantial attention. Various symptoms such as sleep-related problems, headache, tinnitus and vertigo have been described by subjects suspected of having been exposed to wind turbine noise...... existing statistically-significant evidence indicating any association between wind turbine noise exposure and tinnitus, hearing loss, vertigo or headache. LIMITATIONS: Selection bias and information bias of differing magnitudes were found to be present in all current studies investigating wind turbine...

A Fiber-Optic Aircraft Lightning Current Measurement Sensor

Science.gov (United States)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2013-01-01

A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

A Method to Estimate Students’ Exposure to Road Traffic Noise Events

Directory of Open Access Journals (Sweden)

Simone Secchi

2018-03-01

Full Text Available The correlation between exposure to traffic noise and students’ performance and annoyance has been investigated in literature mainly considering the relationship between indoor equivalent A-weighted sound pressure level (LAeq and students’ cognitive impairment. Annoyance is frequently related to the effect of short-duration noise events characterized by high sound pressure levels, such as those due to aircraft fly-over and pass-by of buses, heavy trucks, motorcycles, or street sweepers. These noise events are often described, over specific measurement periods, in terms of maximum A-weighted sound pressure level, LAmax, or statistical levels, such as LA1 or LA10. This aspect is not considered in the noise maps drawn in accordance with the European Environmental Noise Directive, as they provide the LAeq only, determined over day, evening, and night periods. In this paper, students’ exposure to road traffic noise is analyzed by means of regression equations obtained by the authors between LAeq and A-weighted maximum and statistical levels due to road traffic noise. The traffic noise of 28 urban streets was monitored during the opening period of Italian schools. A method is described to estimate students’ exposure to noise from data made available on noise maps by the municipalities of metropolitan areas. The application of this method to the case study of Florence shows that almost 60% of students from municipal primary and lower secondary schools could be exposed to the maximum sound pressure level (SPL inside the classroom greater than 55 dB(A every hour, probably exceeding the typical background noise in classrooms by more than 10 dB.

Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports

Science.gov (United States)

Jansen, Ralph H.; Bowman, Cheryl; Jankovsky, Amy; Dyson, Rodger; Felder, James L.

2017-01-01

NASA is investing in Electrified Aircraft Propulsion (EAP) research as part of the portfolio to improve the fuel efficiency, emissions, and noise levels in commercial transport aircraft. Turboelectric, partially turboelectric, and hybrid electric propulsion systems are the primary EAP configurations being evaluated for regional jet and larger aircraft. The goal is to show that one or more viable EAP concepts exist for narrow body aircraft and mature tall-pole technologies related to those concepts. A summary of the aircraft system studies, technology development, and facility development is provided. The leading concept for mid-term (2035) introduction of EAP for a single aisle aircraft is a tube and wing, partially turbo electric configuration (STARC-ABL), however other viable configurations exist. Investments are being made to raise the TRL level of light weight, high efficiency motors, generators, and electrical power distribution systems as well as to define the optimal turbine and boundary layer ingestion systems for a mid-term tube and wing configuration. An electric aircraft power system test facility (NEAT) is under construction at NASA Glenn and an electric aircraft control system test facility (HEIST) is under construction at NASA Armstrong. The correct building blocks are in place to have a viable, large plane EAP configuration tested by 2025 leading to entry into service in 2035 if the community chooses to pursue that goal.

A study of the cost-effective markets for new technology agricultural aircraft

Science.gov (United States)

Hazelrigg, G. A., Jr.; Clyne, F.

1979-01-01

A previously developed data base was used to estimate the regional and total U.S. cost-effective markets for a new technology agricultural aircraft as incorporating features which could result from NASA-sponsored aerial applications research. The results show that the long-term market penetration of a new technology aircraft would be near 3,000 aircraft. This market penetration would be attained in approximately 20 years. Annual sales would be about 200 aircraft after 5 to 6 years of introduction. The net present value of cost savings benefit which this aircraft would yield (measured on an infinite horizon basis) would be about $35 million counted at a 10 percent discount rate and $120 million at a 5 percent discount rate. At both discount rates the present value of cost savings exceeds the present value of research and development (R&D) costs estimated for the development of the technology base needed for the proposed aircraft. These results are quite conservative as they have been derived neglecting future growth in the agricultural aviation industry, which has been averaging about 12 percent per year over the past several years.

Effect of external classroom noise on schoolchildren's reading and mathematics performance: correlation of noise levels and gender.

Science.gov (United States)

Papanikolaou, M; Skenteris, N; Piperakis, S M

2015-02-01

The present study investigated the effect of low, medium, and high traffic road noise as well as irrelevant background speech noise on primary school children's reading and mathematical performance. A total of 676 participants (324 boys, 47.9% and 352 girls, 52.1%) of the 4th and 5th elementary classes participated in the project. The participants were enrolled in public primary schools from urban areas and had ages ranging from 9 to 10 years and from. Schools were selected on the basis of increasing levels of exposure to road traffic noise and then classified into three categories (Low noise: 55-66 dB, Medium noise: 67-77 dB, and High noise: 72-80 dB). We measured reading comprehension and mathematical skills in accordance with the national guidelines for elementary education, using a test designed specifically for the purpose of this study. On the one hand, children in low-level noise schools showed statistically significant differences from children in medium- and high-level noise schools in reading performance (plevel noise schools differed significantly from children in high-level noise schools but only in mathematics performance (p=0.001). Girls in general did better in reading score than boys, especially in schools with medium- and high-level noise. Finally the levels of noise and gender were found to be two independent factors.

Turbofan Noise Studied in Unique Model Research Program in NASA Glenn's 9- by 15-Foot Low-Speed Wind Tunnel

Science.gov (United States)

Hughes, Christopher E.

2001-01-01

A comprehensive aeroacoustic research program called the Source Diagnostic Test was recently concluded in NASA Glenn Research Center's 9- by 15-Foot Low Speed Wind Tunnel. The testing involved representatives from Glenn, NASA Langley Research Center, GE Aircraft Engines, and the Boeing Company. The technical objectives of this research were to identify the different source mechanisms of noise in a modern, high-bypass turbofan aircraft engine through scale-model testing and to make detailed acoustic and aerodynamic measurements to more fully understand the physics of how turbofan noise is generated.

Flow and Noise Control: Review and Assessment of Future Directions

Science.gov (United States)

Thomas, Russell H.; Choudhari, Meelan M.; Joslin, Ronald D.

2002-01-01

Technologies for developing radically new aerovehicles that would combine quantum leaps in cost, safety, and performance benefits with environmental friendliness have appeared on the horizon. This report provides both an assessment of the current state-of-the-art in flow and noise control and a vision for the potential gains to be made, in terms of performance benefit for civil and military aircraft and a unique potential for noise reduction, via future advances in flow and noise technologies. This report outlines specific areas of research that will enable the breakthroughs necessary to bring this vision to reality. Recent developments in many topics within flow and noise control are reviewed. The flow control overview provides succinct summaries of various approaches for drag reduction and improved maneuvering. Both exterior and interior noise problems are examined, including dominant noise sources, physics of noise generation and propagation, and both established and proposed concepts for noise reduction. Synergy between flow and noise control is a focus and, more broadly, the need to pursue research in a more concurrent approach involving multiple disciplines. Also discussed are emerging technologies such as nanotechnology that may have a significant impact on the progress of flow and noise control.

The Effect of Age and Type of Noise on Speech Perception under Conditions of Changing Context and Noise Levels.

Science.gov (United States)

Taitelbaum-Swead, Riki; Fostick, Leah

2016-01-01

Everyday life includes fluctuating noise levels, resulting in continuously changing speech intelligibility. The study aims were: (1) to quantify the amount of decrease in age-related speech perception, as a result of increasing noise level, and (2) to test the effect of age on context usage at the word level (smaller amount of contextual cues). A total of 24 young adults (age 20-30 years) and 20 older adults (age 60-75 years) were tested. Meaningful and nonsense one-syllable consonant-vowel-consonant words were presented with the background noise types of speech noise (SpN), babble noise (BN), and white noise (WN), with a signal-to-noise ratio (SNR) of 0 and -5 dB. Older adults had lower accuracy in SNR = 0, with WN being the most difficult condition for all participants. Measuring the change in speech perception when SNR decreased showed a reduction of 18.6-61.5% in intelligibility, with age effect only for BN. Both young and older adults used less phonemic context with WN, as compared to other conditions. Older adults are more affected by an increasing noise level of fluctuating informational noise as compared to steady-state noise. They also use less contextual cues when perceiving monosyllabic words. Further studies should take into consideration that when presenting the stimulus differently (change in noise level, less contextual cues), other perceptual and cognitive processes are involved. © 2016 S. Karger AG, Basel.

Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows

Science.gov (United States)

Aloufi, Badr; Behdinan, Kamran; Zu, Jean

2016-06-01

In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.

Intrinsic noise in aggressively scaled field-effect transistors

International Nuclear Information System (INIS)

Albareda, G; Jiménez, D; Oriols, X

2009-01-01

According to roadmap projections, nanoscale field-effect transistors (FETs) with channel lengths below 30 nm and several gates (for improving their gate control over the source–drain conductance) will come to the market in the next few years. However, few studies deal with the noise performance of these aggressively scaled FETs. In this work, a study of the effect of the intrinsic (thermal and shot) noise of such FETs on the performance of an analog amplifier and a digital inverter is carried out by means of numerical simulations with a powerful Monte Carlo (quantum) simulator. The numerical data indicate important drawbacks in the noise performance of aggressively scaled FETs that could invalidate roadmap projections as regards analog and digital applications

Effects of noise on convergent game-learning dynamics

International Nuclear Information System (INIS)

Sanders, James B T; Galla, Tobias; Shapiro, Jonathan L

2012-01-01

We study stochastic effects on the lagging anchor dynamics, a reinforcement learning algorithm used to learn successful strategies in iterated games, which is known to converge to Nash points in the absence of noise. The dynamics is stochastic when players only have limited information about their opponents’ strategic propensities. The effects of this noise are studied analytically in the case where it is small but finite, and we show that the statistics and correlation properties of fluctuations can be computed to a high accuracy. We find that the system can exhibit quasicycles, driven by intrinsic noise. If players are asymmetric and use different parameters for their learning, a net payoff advantage can be achieved due to these stochastic oscillations around the deterministic equilibrium. (paper)

The effect of total noise on two-dimension OCDMA codes

Science.gov (United States)

Dulaimi, Layth A. Khalil Al; Badlishah Ahmed, R.; Yaakob, Naimah; Aljunid, Syed A.; Matem, Rima

2017-11-01

In this research, we evaluate the performance of total noise effect on two dimension (2-D) optical code-division multiple access (OCDMA) performance systems using 2-D Modified Double Weight MDW under various link parameters. The impact of the multi-access interference (MAI) and other noise effect on the system performance. The 2-D MDW is compared mathematically with other codes which use similar techniques. We analyzed and optimized the data rate and effective receive power. The performance and optimization of MDW code in OCDMA system are reported, the bit error rate (BER) can be significantly improved when the 2-D MDW code desired parameters are selected especially the cross correlation properties. It reduces the MAI in the system compensate BER and phase-induced intensity noise (PIIN) in incoherent OCDMA The analysis permits a thorough understanding of PIIN, shot and thermal noises impact on 2-D MDW OCDMA system performance. PIIN is the main noise factor in the OCDMA network.

The effect of total noise on two-dimension OCDMA codes

Directory of Open Access Journals (Sweden)

Khalil Al Dulaimi Layth A.

2017-01-01

Full Text Available In this research, we evaluate the performance of total noise effect on two dimension (2-D optical code-division multiple access (OCDMA performance systems using 2-D Modified Double Weight MDW under various link parameters. The impact of the multi-access interference (MAI and other noise effect on the system performance. The 2-D MDW is compared mathematically with other codes which use similar techniques. We analyzed and optimized the data rate and effective receive power. The performance and optimization of MDW code in OCDMA system are reported, the bit error rate (BER can be significantly improved when the 2-D MDW code desired parameters are selected especially the cross correlation properties. It reduces the MAI in the system compensate BER and phase-induced intensity noise (PIIN in incoherent OCDMA The analysis permits a thorough understanding of PIIN, shot and thermal noises impact on 2-D MDW OCDMA system performance. PIIN is the main noise factor in the OCDMA network.

Assessment and Mitigation of the Effects of Noise on Habitability in Deep Space Environments: Report on Non-Auditory Effects of Noise

Science.gov (United States)

Begault, Durand R.

2018-01-01

This document reviews non-auditory effects of noise relevant to habitable volume requirements in cislunar space. The non-auditory effects of noise in future long-term space habitats are likely to be impactful on team and individual performance, sleep, and cognitive well-being. This report has provided several recommendations for future standards and procedures for long-term space flight habitats, along with recommendations for NASA's Human Research Program in support of DST mission success.

The effects of noise-bandwidth, noise-fringe duration, and temporal signal location on the binaural masking-level difference.

Science.gov (United States)

Yasin, Ifat; Henning, G Bruce

2012-07-01

The effects of forward and backward noise fringes on binaural signal detectability were investigated. Masked thresholds for a 12-ms, 250-Hz, sinusoidal signal masked by Gaussian noise, centered at 250 Hz, with bandwidths from 3 to 201 Hz, were obtained in N(0)S(0) and N(0)S(π) configurations. The signal was (a) temporally centered in a 12-ms noise burst (no fringe), (b) presented at the start of a 600-ms noise burst (backward fringe), or (c) temporally centered in a 600-ms noise burst (forward-plus-backward fringe). For noise bandwidths between 3 and 75 Hz, detection in N(0)S(0) improved with the addition of a backward fringe, improving further with an additional forward fringe; there was little improvement in N(0)S(π). The binaural masking-level difference (BMLD) increased from 0 to 8 dB with a forward-plus-backward fringe as noise bandwidths increased to 100 Hz, increasing slightly to 10 dB at 201 Hz. This two-stage increase was less pronounced with a backward fringe. With no fringe, the BMLD was about 10-14 dB at all bandwidths. Performance appears to result from the interaction of across-time and across-frequency listening strategies and the possible effects of gain reduction and suppression, which combine in complex ways. Current binaural models are, as yet, unable to account fully for these effects.

14 CFR Appendix G to Part 36 - Takeoff Noise Requirements for Propeller-Driven Small Airplane and Propeller-Driven, Commuter...

Science.gov (United States)

2010-01-01

... OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Pt. 36, App... conforming to the specifications in section G36.105 of this appendix must be reported. (c) The type of... determined by an approved method independent of normal flight instrumentation, such as radar tracking...

Recent advances in research on non-auditory effects of community noise

Directory of Open Access Journals (Sweden)

Belojević Goran

2016-01-01

Full Text Available Non-auditory effects of noise on humans have been intensively studied in the last four decades. The International Commission on Biological Effects of Noise has been following scientific advances in this field by organizing international congresses from the first one in 1968 in Washington, DC, to the 11th congress in Nara, Japan, in 2014. There is already a large scientific body of evidence on the effects of noise on annoyance, communication, performance and behavior, mental health, sleep, and cardiovascular functions including relationship with hypertension and ischemic heart disease. In the last five years new issues in this field have been tackled. Large epidemiological studies on community noise have reported its relationship with breast cancer, stroke, type 2 diabetes, and obesity. It seems that noise-induced sleep disturbance may be one of the mediating factors in these effects. Given a large public health importance of the above-mentioned diseases, future studies should more thoroughly address the mechanisms underlying the reported association with community noise exposure. [Projekat Ministarstva nauke Republike Srbije, br. 175078

Toward Active Control of Noise from Hot Supersonic Jets

Science.gov (United States)

2012-11-15

et al. (2011a), the Mach number chosen for this study is not typical of commercial or military aircraft engines, and bears little relevance to most...CHRISTOPHER K. W., VISWANATHAN, K., AHUJA, K. K. & PANDA , J. 2008 The sources of jet noise: experimental evidence. J. Fluid Mech. 615, 253-292. TANNA, H. K

Extraction of Lateral-Directional Stability and Control Derivatives for the Basic F-18 Aircraft at High Angles of Attack

Science.gov (United States)

Iliff, Kenneth W.; Wang, Kon-Sheng Charles

1997-01-01

The results of parameter identification to determine the lateral-directional stability and control derivatives of an F-18 research aircraft in its basic hardware and software configuration are presented. The derivatives are estimated from dynamic flight data using a specialized identification program developed at NASA Dryden Flight Research Center. The formulation uses the linearized aircraft equations of motions in their continuous/discrete form and a maximum likelihood estimator that accounts for both state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics, such as separated and vortical flows, over the aircraft. The derivatives are plotted as functions of angle of attack between 3 deg and 47 deg and compared with wind-tunnel predictions. The quality of the derivative estimates obtained by parameter identification is somewhat degraded because the maneuvers were flown with the aircraft's control augmentation system engaged, which introduced relatively high correlations between the control variables and response variables as a result of control motions from the feedback control system.

Effect of power system technology and mission requirements on high altitude long endurance aircraft

Science.gov (United States)

Colozza, Anthony J.

1994-01-01

An analysis was performed to determine how various power system components and mission requirements affect the sizing of a solar powered long endurance aircraft. The aircraft power system consists of photovoltaic cells and a regenerative fuel cell. Various characteristics of these components, such as PV cell type, PV cell mass, PV cell efficiency, fuel cell efficiency, and fuel cell specific mass, were varied to determine what effect they had on the aircraft sizing for a given mission. Mission parameters, such as time of year, flight altitude, flight latitude, and payload mass and power, were also altered to determine how mission constraints affect the aircraft sizing. An aircraft analysis method which determines the aircraft configuration, aspect ratio, wing area, and total mass, for maximum endurance or minimum required power based on the stated power system and mission parameters is presented. The results indicate that, for the power system, the greatest benefit can be gained by increasing the fuel cell specific energy. Mission requirements also substantially affect the aircraft size. By limiting the time of year the aircraft is required to fly at high northern or southern latitudes, a significant reduction in aircraft size or increase in payload capacity can be achieved.

The Effect of Noise on Human Performance: A Clinical Trial

Directory of Open Access Journals (Sweden)

P Nassiri

2013-04-01

Full Text Available Background: Noise is defined as unwanted or meaningless sound that apart from auditory adverse health effects may distract attention from cues that are important for task performance. Human performance is influenced by many job-related factors and workplace conditions including noise level. Objective: To study the effect of noise on human performance. Methods: The participants included 40 healthy male university students. The experimental design consisted of 3 (sound pressure level x 3 (noise schedule x 2 (noise type factors. To investigate occupational skill performance, some specific test batteries were used: 1 steadiness test, 2 Minnesota manual dexterity test, 3 hand tool dexterity test, and 4 two-arm coordination test. Time duration of test completion was measured as speed response; to determine error response, the time taken during committing an error by participants while performing a task was measured. Results: Speed response obtained from the 4 tests in combined conditions of noise schedule, harmonic index, and sound pressure level was highest for (intermittent, treble, 95 dB, (continuous, treble, 95 dB, (continuous, treble, 85 dB and (intermittent, treble, 95 dB, respectively. Conclusion: Treble noise was found significant in reducing human performance; also, intermittent noise, especially at high pressure levels, was responsible for worsening environmental conditions during performing a task.

14 CFR Appendix B to Part 150 - Noise Compatibility Programs

Science.gov (United States)

2010-01-01

...) The implementation of any restriction on the use of airport by any type or class of aircraft based on... purpose. (a) This appendix prescribes the content and the methods for developing noise compatibility... identify existing and future noncompatible land uses, based on airport operation and off-airport land uses...

Measurements of effective noise temperature in fused silica fiber violin modes

Energy Technology Data Exchange (ETDEWEB)

Bilenko, I.A.; Lourie, S.L

2002-11-25

The results of measurements of the effective noise temperature in fused silica fiber violin modes are presented. In these measurements the fibers were stressed and value of the effective noise temperature was obtained by direct observation of oscillations in the fundamental violin modes of several samples. Measured values indicate that effective noise temperature does not exceed the room temperature significantly. This result is important for the design of the advanced gravitational wave antennae.

Making Aircraft Vortices Visible to Radar by Spraying Water into the Wake

Science.gov (United States)

Shariff, Karim

2016-01-01

Aircraft trailing vortices pose a danger to following aircraft during take-off and landing. This necessitates spacing rules, based on aircraft type, to be enforced during approach in IFR (Instrument Flight Regulations) conditions; this can limit airport capacity. To help choose aircraft spacing based on the actual location and strength of the wake, it is proposed that wake vortices can be detected using conventional precipitation and cloud radars. This is enabled by spraying a small quantity water into the wake from near the wing. The vortex strength is revealed by the doppler velocity of the droplets. In the present work, droplet size distributions produced by nozzles used for aerial spraying are considered. Droplet trajectory and evaporation in the flow-field is numerically calculated for a heavy aircraft, followed by an evaluation of radar reflectivity at 6 nautical miles behind the aircraft. Small droplets evaporate away while larger droplets fall out of the wake. In the humid conditions that typically prevail during IFR, a sufficient number of droplets remain in the wake and give good signal-to-noise ratios (SNR). For conditions of average humidity, higher frequency radars combined with spectral processing gives good SNR.

Noise effect in metabolic networks

International Nuclear Information System (INIS)

Zheng-Yan, Li; Zheng-Wei, Xie; Tong, Chen; Qi, Ouyang

2009-01-01

Constraint-based models such as flux balance analysis (FBA) are a powerful tool to study biological metabolic networks. Under the hypothesis that cells operate at an optimal growth rate as the result of evolution and natural selection, this model successfully predicts most cellular behaviours in growth rate. However, the model ignores the fact that cells can change their cellular metabolic states during evolution, leaving optimal metabolic states unstable. Here, we consider all the cellular processes that change metabolic states into a single term 'noise', and assume that cells change metabolic states by randomly walking in feasible solution space. By simulating a state of a cell randomly walking in the constrained solution space of metabolic networks, we found that in a noisy environment cells in optimal states tend to travel away from these points. On considering the competition between the noise effect and the growth effect in cell evolution, we found that there exists a trade-off between these two effects. As a result, the population of the cells contains different cellular metabolic states, and the population growth rate is at suboptimal states. (cross-disciplinary physics and related areas of science and technology)

Effects on Performance and Work Quality due to Low Frequency Ventilation Noise

Science.gov (United States)

Persson Waye, K.; Rylander, R.; Benton, S.; Leventhall, H. G.

1997-08-01

A pilot study was carried out to assess method evaluating effects of low frequency noise on performance. Of special interest was to study objective and subjective effects over time. Two ventilation noises were used, one of a predominantly mid frequency character and the other of a predominantly low frequency character. Both had an NC value of 35. For the study, 50 students were recruited and 30 selected on the basis of subjective reports of pressure on the eardrum after exposure to a low frequency noise. Of these, 14 randomly selected subjects aged 21 and 34 took part. The subjects performed three computerized cognitive tests in the mid frequency or the low frequency noise condition alternatively. Tests I and II were performed together with a secondary task.Questionnaires were used to evaluate subjective symptoms, effects on mood and estimated interference with the test results due to temperature, light and noise. The results showed that the subjective estimations of noise interference with performance were higher for the low frequency noise (psocial orientation (pstudied. The results further indicate that the NC curves do not fully assess the negative effects of low frequency noise on work performance.

Noise pollution has limited effects on nocturnal vigilance in peahens

OpenAIRE

Yorzinski, Jessica L.; Hermann, Fredrick S.

2016-01-01

Natural environments are increasingly exposed to high levels of noise pollution. Noise pollution can alter the behavior of animals but we know little about its effects on antipredator behavior. We therefore investigated the impact of noise pollution on vigilance behavior and roost selection in an avian species, peafowl (Pavo cristatus), that inhabits urban environments. Captive peahens were exposed to noise pollution at night and their vigilance levels and roost selections were monitored. The...

Study of V/STOL aircraft implementation. Volume 1: Summary

Science.gov (United States)

Portenier, W. J.; Webb, H. M.

1973-01-01

A high density short haul air market which by 1980 is large enough to support the introduction of an independent short haul air transportation system is discussed. This system will complement the existing air transportation system and will provide relief of noise and congestion problems at conventional airports. The study has found that new aircraft, exploiting V/STOL and quiet engine technology, can be available for implementing these new services, and they can operate from existing reliever and general aviation airports. The study has also found that the major funding requirements for implementing new short haul services could be borne by private capital, and that the government funding requirement would be minimal and/or recovered through the airline ticket tax. In addition, a suitable new short haul aircraft would have a market potential for $3.5 billion in foreign sales. The long lead times needed for aircraft and engine technology development will require timely actions by federal agencies.

Effects of Colored Noise on Periodic Orbits in a One-Dimensional Map

Science.gov (United States)

Li, Feng-Guo; Ai, Bao-Quan

2011-06-01

Noise can induce inverse period-doubling transition and chaos. The effects of the colored noise on periodic orbits, of the different periodic sequences in the logistic map, are investigated. It is found that the dynamical behaviors of the orbits, induced by an exponentially correlated colored noise, are different in the mergence of transition, and the effects of the noise intensity on their dynamical behaviors are different from the effects of the correlation time of noise. Remarkably, the noise can induce new periodic orbits, namely, two new orbits emerge in the period-four sequence at the bifurcation parameter value μ = 3.5, four new orbits in the period-eight sequence at μ = 3.55, and three new orbits in the period-six sequence at μ = 3.846, respectively. Moreover, the dynamical behaviors of the new orbits clearly show the resonancelike response to the colored noise.

Effects of Colored Noise on Periodic Orbits in a One-Dimensional Map

International Nuclear Information System (INIS)

Li Fengguo; Ai Baoquan

2011-01-01

Noise can induce inverse period-doubling transition and chaos. The effects of the colored noise on periodic orbits, of the different periodic sequences in the logistic map, are investigated. It is found that the dynamical behaviors of the orbits, induced by an exponentially correlated colored noise, are different in the mergence of transition, and the effects of the noise intensity on their dynamical behaviors are different from the effects of the correlation time of noise. Remarkably, the noise can induce new periodic orbits, namely, two new orbits emerge in the period-four sequence at the bifurcation parameter value μ = 3.5, four new orbits in the period-eight sequence at μ = 3.55, and three new orbits in the period-six sequence at μ = 3.846, respectively. Moreover, the dynamical behaviors of the new orbits clearly show the resonancelike response to the colored noise. (general)

Effects of noise overexposure on distortion product otoacoustic emissions

DEFF Research Database (Denmark)

de Toro, Miguel Angel Aranda

are assumed to be equally hazardous for our hearing. Nevertheless, the standard allows adding a +5dB penalty to impulsive and tonal noises based on the presumption that they might pose a higher risk of hearing loss. This PhD thesis investigates the effect of different occupational noise exposures......The risk of noise-induced hearing loss (NIHL) at the workplace can be predicted according to the International Standard ISO 1999:1990. The standard is applicable to all types of noise and it is based on measurements of the total acoustic energy (LEX,8ℎ). Therefore, noises with equal energy...... may be more appropriate for tonal exposures. This presentation will also address methodological aspects of DPOAE measurements that might improve hearing diagnosis and detection of hearing loss....

Effect of noise on the standard mapping

International Nuclear Information System (INIS)

Karney, C.F.F.; Rechester, A.B.; White, R.B.

1981-03-01

The effect of a small amount of noise on the standard mapping is considered. Whenever the standard mapping possesses accelerator models (where the action increases approximately linearly with time), the diffusion coefficient contains a term proportional to the reciprocal of the variance of the noise term. At large values of the stochasticity parameter, the accelerator modes exhibit a universal behavior. As a result the dependence of the diffusion coefficient on stochasticity parameter also shows some universal behavior

Knowledge on the Effects and Perceived Health Problems of Noise ...

African Journals Online (AJOL)

There is a growing concern on the increase of noise induced hearing impairment in developing nations. Academic settings have been reported to be plagued by noise levels that affect cognitive activities. However, there is paucity of information on the level of knowledge on the effects of noise and the reported health ...

On the Connection Between Flap Side-Edge Noise and Tip Vortex Dynamics

Science.gov (United States)

Casalino, D.; Hazir, A.; Fares, E.; Duda, B.; Khorrami, M. R.

2015-01-01

The goal of the present work is to investigate how the dynamics of the vortical flow about the flap side edge of an aircraft determine the acoustic radiation. A validated lattice- Boltzmann CFD solution of the unsteady flow about a detailed business jet configuration in approach conditions is used for the present analysis. Evidence of the connection between the noise generated by several segments of the inboard flap tip and the aerodynamic forces acting on the same segments is given, proving that the noise generation mechanism has a spatially coherent and acoustically compact character on the scale of the flap chord, and that the edge-scattering effects are of secondary importance. Subsequently, evidence of the connection between the kinematics of the tip vortex system and the aerodynamic force is provided. The kinematics of the dual vortex system are investigated via a core detection technique. Emphasis is placed on the mutual induction effects between the two main vortices rolling up from the pressure and suction sides of the flap edge. A simple heuristic formula that relates the far-field noise spectrum and the cross-spectrum of the unsteady vortical positions is developed.

41 CFR 301-70.903 - What are our responsibilities for ensuring that Government aircraft are the most cost-effective...

Science.gov (United States)

2010-07-01

... responsibilities for ensuring that Government aircraft are the most cost-effective alternative for travel? 301-70... our responsibilities for ensuring that Government aircraft are the most cost-effective alternative for travel? To help ensure that Government aircraft are the most cost-effective alternative for travel, your...

Effect of noise in computed tomographic reconstructions on detectability

International Nuclear Information System (INIS)

Hanson, K.M.

1982-01-01

The detectability of features in an image is ultimately limited by the random fluctuations in density or noise present in that image. The noise in CT reconstructions arising from the statistical fluctuations in the one-dimensional input projection measurements has an unusual character owing to the reconstruction procedure. Such CT image noise differs from the white noise normally found in images in its lack of low-frequency components. The noise power spectrum of CT reconstructions can be related to the effective density of x-ray quanta detected in the projection measurements, designated as NEQ (noise-equivalent quanta). The detectability of objects that are somewhat larger than the spatial resolution is directly related to NEQ. Since contrast resolution may be defined in terms of the ability to detect large, low-contrast objects, the measurement of a CT scanner's NEQ may be used to characterize its contrast sensitivity

Investigating potential correlations between jet engine noise and plume dynamics in the hypertemporal infrared domain

Science.gov (United States)

Cunio, Phillip M.; Weber, Reed; Knobel, Kimberly; Wager, Jason; Lopez, Gerardo

2014-09-01

Jet engine noise can be a hazard and environmental pollutant, affecting personnel working in close proximity to jet engines. Mitigating the effects of jet engine noise could reduce the potential for hearing loss in runway workers, but engine noise is not yet sufficiently well-characterized that it can easily be mitigated for new engine designs. That is, there exists a very complex relationship between jet engine design parameters, operating conditions, and resultant noise power levels. In this paper, we propose to evaluate the utility of high-speed imaging (also called hypertemporal imaging) in correlating the infrared signatures of jet aircraft engines with acoustic noise from the jet engines. This paper will focus on a theoretical analysis of jet engine infrared signatures, and will define potentially-detectable characteristics of such signatures in the hypertemporal domain. A systematic test campaign to determine whether such signatures actually exist and can be correlated with acoustic jet engine characteristics will be proposed. The detection of any hypertemporal signatures in association with acoustic signatures of jet engines will enable the use of a new domain in characterizing jet engine noise. This may in turn enable new methods of predicting or mitigating jet engine noise, which could lead to benefits for operators of large numbers of jet engines.

Noise annoys: effects of noise on breeding great tits depend on personality but not on noise characteristics

NARCIS (Netherlands)

Naguib, M.; Van Oers, K.; Braakhuis, A.; Griffioen, M.; De Goede, P.; Waas, J.R.

2013-01-01

Anthropogenic noise can have serious implications for animals, especially when they communicate acoustically. Yet, the impacts of noise may depend not only on noise characteristics but also on an individual's coping style or personality. We tested whether noise is more disturbing if it masks

An examination of the parametric properties of four noise sensitivity measures

DEFF Research Database (Denmark)

van Kamp, Irene; Ellermeier, Wolfgang; Lopez-Barrio, Isabel

2006-01-01

Noise sensitivity (NS) is a personality trait with a strong influence on reactions to noise. Studies of reaction should include a standard measure of NS that is founded on a theoretically justified definition of NS, and examination of existing NS measures' parametric properties (internal consiste......, demographics and lifestyle). A standard NS measure should demonstrate high reliability, and should predict responses to noise. Discussion is welcomed and will focus on validation strategies and optimizing the study design.......Noise sensitivity (NS) is a personality trait with a strong influence on reactions to noise. Studies of reaction should include a standard measure of NS that is founded on a theoretically justified definition of NS, and examination of existing NS measures' parametric properties (internal...... consistency; stability; convergent and predictive validity). At each of 6 laboratory centres (Aalborg; London; Sydney; Dortmund; Madrid, Amsterdam), participants will complete four NS measures on each of two occasions. In one occasion, participants will complete a task while exposed to recorded aircraft noise...

Review of Design Aspects and Challenges of Efficient and Quiet Amphibious Aircraft

Science.gov (United States)

D, Rhea P. Liem Ph.

2018-04-01

Apart from the commercial and military aviation sectors, the general aviation (GA) sector is expected to experience a rapid growth, especially in Asia. The increasing economic activities in the region would demand for more efficient and convenient transportation, which would open door to more GA services. This development would require sufficient infrastructure supports, including airports. However, insufficient land area has often imposed limitations in airport development. As such, some areas (e.g., remote islands) are not easily accessible by air. One implication is that travels can only be done via land or water, which might prolong the travel time. This applies to business travels, with the significant increase in business and economic activities, which in turns demands for more efficient and faster mobility. In other cases, this involves some rural areas where the infrastructures are not very well-developed, and where the geographical terrains are too challenging to build a pad for vertical takeoff and landing (VTOL) air vehicles. Under such circumstances, it would be imperative to enable air travels to carry critical logistics such as medical supplies, food, and even sick patients. In this regard, we propose to develop a low-payload, low-altitude amphibious aircraft, which can takeoff and land on both water and land. Aircraft design process is a complex procedure and multidisciplinary in nature, and for amphibious aircraft design we need to consider the two takeoff and landing modes, which imposes further challenges to the design. In this paper we present two preliminary design projects, for two-seater and ten-seater aircraft. To design an efficient and quiet amphibious aircraft, we conduct some experiments on noise shielding mechanisms to reduce the propeller noise. The challenges and resulting designs are briefly discussed in this paper. Amphibious aircraft development will be very relevant to Indonesia, which is the world’s largest archipelago with

Sensorineural hearing loss associated with occupational noise exposure: effects of age-corrections.

Science.gov (United States)

Krishnamurti, Sridhar

2009-03-01

Noise-induced permanent threshold shifts (NIPTS) were computed from retrospective audiometric analyses by subtracting aging effects on hearing sensitivity in sixty-eight patients with bilateral sensorineural hearing loss who reported significant occupational noise exposure histories. There were significant effects of age on NIPTS but no significant gender- or ear- differences in terms of NIPTS. The NIPTS at 2,000 Hz was found to be significantly greater than NIPTS at frequencies 500 Hz, 1,000 Hz, 4,000 Hz, and 8,000 Hz. Defined noise notches were seen in the audiograms of 38/136 (27%) ears with SNHL. Results support models that suggest interactive effects of aging and noise on sensorineural hearing loss in ears with occupational noise exposure.

Effects of Tidal Turbine Noise on Fish Task 2.1.3.2: Effects on Aquatic Organisms: Acoustics/Noise - Fiscal Year 2011 - Progress Report - Environmental Effects of Marine and Hydrokinetic Energy

Energy Technology Data Exchange (ETDEWEB)

Halvorsen, Michele B.; Carlson, Thomas J.; Copping, Andrea E.

2011-09-30

Naturally spawning stocks of Chinook salmon (Oncorhynchus tshawytscha) that utilize Puget Sound are listed as threatened (http://www.nwr.noaa.gov/ESA-Salmon-Listings/Salmon-Populations/ Chinook/CKPUG.cfm). Plans exist for prototype tidal turbines to be deployed into their habitat. Noise is known to affect fish in many ways, such as causing a threshold shift in auditory sensitivity or tissue damage. The characteristics of noise, its spectra and level, are important factors that influence the potential for the noise to injure fish. For example, the frequency range of the tidal turbine noise includes the audiogram (frequency range of hearing) of most fish. This study (Effects on Aquatic Organisms, Subtask 2.1.3.2: Acoustics) was performed during FY 2011 to determine if noise generated by a 6-m-diameter open-hydro turbine might affect juvenile Chinook salmon hearing or cause barotrauma. After they were exposed to simulated tidal turbine noise, the hearing of juvenile Chinook salmon was measured and necropsies performed to check for tissue damage. Experimental groups were (1) noise exposed, (2) control (the same handling as treatment fish but without exposure to tidal turbine noise), and (3) baseline (never handled). Preliminary results indicate that low levels of tissue damage may have occurred but that there were no effects of noise exposure on the auditory systems of the test fish.

Effects of ocular aberrations on contrast detection in noise.

Science.gov (United States)

Liang, Bo; Liu, Rong; Dai, Yun; Zhou, Jiawei; Zhou, Yifeng; Zhang, Yudong

2012-08-06

We use adaptive optics (AO) techniques to manipulate the ocular aberrations and elucidate the effects of these ocular aberrations on contrast detection in a noisy background. The detectability of sine wave gratings at frequencies of 4, 8, and 16 circles per degree (cpd) was measured in a standard two-interval force-choice staircase procedure against backgrounds of various levels of white noise. The observer's ocular aberrations were either corrected with AO or left uncorrected. In low levels of external noise, contrast detection thresholds are always lowered by AO correction, whereas in high levels of external noise, they are generally elevated by AO correction. Higher levels of external noise are required to make this threshold elevation observable when signal spatial frequencies increase from 4 to 16 cpd. The linear-amplifier-model fit shows that mostly sampling efficiency and equivalent noise both decrease with AO correction. Our findings indicate that ocular aberrations could be beneficial for contrast detection in high-level noises. The implications of these findings are discussed.

Energy conservation aircraft design and operational procedures

Energy Technology Data Exchange (ETDEWEB)

Poisson-Quinton, P.

1978-01-01

The paper reviews studies associated with improved fuel efficiency. Several aircraft design concepts are described including: (1) increases in aerodynamic efficiency through decreased friction drag, parasitic drag, and drag due to lift, (2) structural efficiency and the implementation of composite materials, (3) active control technology, (4) the optimization of airframe-engine integration, and (5) VTOL and STOL concepts. Consideration is also given to operational procedures associated with flight management, terminal-area operations, and the influence of environmental noise constraints on fuel economy.

The effectiveness of environmental strategies on noise reduction in a pediatric intensive care unit: creation of single-patient bedrooms and reducing noise sources.

Science.gov (United States)

Kol, Emine; Aydın, Perihan; Dursun, Oguz

2015-07-01

Noise is a substantial problem for both patients and healthcare workers in hospitals. This study aimed to determine the effectiveness of environmental strategies (creating single-patient rooms and reducing noise sources) in noise reduction in a pediatric intensive care unit. Noise measurement in the unit was conducted in two phases. In the first phase, measurements aimed at determining the unit's present level of noise were performed over 4 weeks in December 2013. During the month following the first measurement phase, the intensive care unit (ICU) was moved to a new location and noise-reducing strategies were implemented. The second phase, in May 2014, measured noise levels in the newly constructed environment. The noise levels before and after environmental changes were statistically significant at 72.6 dB-A and 56 dB-A, respectively (p noise-reducing strategies can be effective in controlling environmental noise in the ICU. © 2015, Wiley Periodicals, Inc.

Long Range Aircraft Trajectory Prediction

OpenAIRE

Magister, Tone

2009-01-01

The subject of the paper is the improvement of the aircraft future trajectory prediction accuracy for long-range airborne separation assurance. The strategic planning of safe aircraft flights and effective conflict avoidance tactics demand timely and accurate conflict detection based upon future four–dimensional airborne traffic situation prediction which is as accurate as each aircraft flight trajectory prediction. The improved kinematics model of aircraft relative flight considering flight ...

Effect of external noise on the current response in superlattices

International Nuclear Information System (INIS)

Suqing Duan; Wu Binyi; Wang Zhigang; Zhao Xiangeng

2004-01-01

Within the single-band model and the nearest-neighbor approximation we investigate the effect of external noise on the current response driven by dc-ac field which has a fluctuating component. We find the external noise can destroy the current resonant peaks. When the strength of the external noise becomes enough large, all the current resonant peaks will completely disappear

Living in a noisy world: indirect effects of noise on animal communication

NARCIS (Netherlands)

Naguib, M.

2013-01-01

Noise is a ubiquitous feature in natural as well as in urban habitats. The presence of noise can have multiple direct and indirect effects on communication. Noise can directly mask signals leading to reduced detection and recognition. Noise also affects internal physiological processes which can

Sensorineural Hearing Loss Associated with Occupational Noise Exposure: Effects of Age-Corrections

Directory of Open Access Journals (Sweden)

2009-02-01

Full Text Available Noise-induced permanent threshold shifts (NIPTS were computed from retrospective audiometric analyses by subtracting aging effects on hearing sensitivity in sixty-eight patients with bilateral sensorineural hearing loss who reported significant occupational noise exposure histories. There were significant effects of age on NIPTS but no significant gender- or ear- differences in terms of NIPTS. The NIPTS at 2,000 Hz was found to be significantly greater than NIPTS at frequencies 500 Hz, 1,000 Hz, 4,000 Hz, and 8,000 Hz. Defined noise notches were seen in the audiograms of 38/136 (27% ears with SNHL. Results support models that suggest interactive effects of aging and noise on sensorineural hearing loss in ears with occupational noise exposure.

An artificial neural network approach for aerodynamic performance retention in airframe noise reduction design of a 3D swept wing model

Directory of Open Access Journals (Sweden)

Tao Jun

2016-10-01

Full Text Available With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Thus, reducing airframe noise makes a great contribution to the overall noise reduction of a civil aircraft. However, reducing airframe noise often leads to aerodynamic performance loss in the meantime. In this case, an approach based on artificial neural network is introduced. An established database serves as a basis and the training sample of a back propagation (BP artificial neural network, which uses confidence coefficient reasoning method for optimization later on. Then the most satisfactory configuration is selected for validating computations through the trained BP network. On the basis of the artificial neural network approach, an optimization process of slat cove filler (SCF for high lift devices (HLD on the Trap Wing is presented. Aerodynamic performance of both the baseline and optimized configurations is investigated through unsteady detached eddy simulations (DES, and a hybrid method, which combines unsteady DES method with acoustic analogy theory, is employed to validate the noise reduction effect. The numerical results indicate not merely a significant airframe noise reduction effect but also excellent aerodynamic performance retention simultaneously.

Cartesian Mesh Linearized Euler Equations Solver for Aeroacoustic Problems around Full Aircraft

Directory of Open Access Journals (Sweden)

Yuma Fukushima

2015-01-01

Full Text Available The linearized Euler equations (LEEs solver for aeroacoustic problems has been developed on block-structured Cartesian mesh to address complex geometry. Taking advantage of the benefits of Cartesian mesh, we employ high-order schemes for spatial derivatives and for time integration. On the other hand, the difficulty of accommodating curved wall boundaries is addressed by the immersed boundary method. The resulting LEEs solver is robust to complex geometry and numerically efficient in a parallel environment. The accuracy and effectiveness of the present solver are validated by one-dimensional and three-dimensional test cases. Acoustic scattering around a sphere and noise propagation from the JT15D nacelle are computed. The results show good agreement with analytical, computational, and experimental results. Finally, noise propagation around fuselage-wing-nacelle configurations is computed as a practical example. The results show that the sound pressure level below the over-the-wing nacelle (OWN configuration is much lower than that of the conventional DLR-F6 aircraft configuration due to the shielding effect of the OWN configuration.

Low-frequency noise in planar Hall effect bridge sensors

DEFF Research Database (Denmark)

Persson, Anders; Bejhedb, R.S.; Bejhed, R.S.

2011-01-01

The low-frequency characteristics of planar Hall effect bridge sensors are investigated as function of the sensor bias current and the applied magnetic field. The noise spectra reveal a Johnson-like spectrum at high frequencies, and a 1/f-like excess noise spectrum at lower frequencies, with a kn...

Unstructured, High-Order Scheme Module with Low Dissipation Flux Difference Splitting for Noise Prediction, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Thorough understanding of aircraft airframe and engine noise mechanisms and the subsequent acoustic propagation to the farfield is necessary to develop and evaluate...

Unmanned Aircraft Systems: The Road to Effective Integration

National Research Council Canada - National Science Library

Petrock, Christopher T; Huizenga, Thomas D

2006-01-01

...) sharing airspace with manned assets. There have been at least two recent collisions between unmanned and rotary-wing aircraft at lower altitudes in Iraq, as well as numerous near misses with fixed-wing aircraft at higher altitudes...

A Health-Based Metric for Evaluating the Effectiveness of Noise Barrier Mitigation Associated With Transport Infrastructure Noise

Directory of Open Access Journals (Sweden)

Geoffrey P Prendergast

2017-01-01

Full Text Available Introduction: This study examines the use of the number of night-time sleep disturbances as a health-based metric to assess the cost effectiveness of rail noise mitigation strategies for situations, wherein high-intensity noises dominate such as freight train pass-bys and wheel squeal. Materials and Methods: Twenty residential properties adjacent to the existing and proposed rail tracks in a noise catchment area of the Epping to Thornleigh Third Track project were used as a case study. Awakening probabilities were calculated for individual’s awakening 1, 3 and 5 times a night when subjected to 10 independent freight train pass-by noise events using internal maximum sound pressure levels (LAFmax. Results: Awakenings were predicted using a random intercept multivariate logistic regression model. With source mitigation in place, the majority of the residents were still predicted to be awoken at least once per night (median 88.0%, although substantial reductions in the median probabilities of awakening three and five times per night from 50.9 to 29.4% and 9.2 to 2.7%, respectively, were predicted. This resulted in a cost-effective estimate of 7.6–8.8 less people being awoken at least three times per night per A$1 million spent on noise barriers. Conclusion: The study demonstrates that an easily understood metric can be readily used to assist making decisions related to noise mitigation for large-scale transport projects.

Development of composite aircraft components in INCDT COMOTI, Bucharest

Directory of Open Access Journals (Sweden)

Raluca VOICU

2012-12-01

Full Text Available This paper presents the recent research activities within INCDT COMOTI, in the composite materials field. The author makes a short introduction of this field and presents an example of application developed within the composite materials laboratory from INCDT COMOTI, targeting the aeronautic field. The aircraft component is a stator blade made of CFRP composites, integrating new active noise reduction technologies and manufactured by means of the autoclave technology.

Magnetic disturbance effects in noise thermometry

International Nuclear Information System (INIS)

Fischer, M.

1992-01-01

Due to the very small measurement signals, a compensation process is used, which presupposes undisturbed signals of the measurement resistance and a compensation resistance as necessary conditions. There is a two-channel control for the measurement and compensation circuit, so that parasitic noise voltages from the incoming leads and the electronics can be eliminated by cross-correlation. The sensor which is designed as a combined thermocouple/noise thermometer sensor, permits continuous measurement of temperature by measuring the thermal voltages and the in situ calibration of the thermocouples at all times, which may have considerable drift of the thermal voltages, depending on environmental effects. Leads designed as thermocouples use ferromagnetic materials, in part. (orig./DG) [de

Long-term effect of noise exposure during military service in South Korea.

Science.gov (United States)

Kim, SungHee; Lim, Eun Jung; Kim, Tae Hoon; Park, Jun Ho

2017-02-01

Most Korean men spend at least two years in the military service usually in their early twenties. The aim of this study was to identify the long-term effect of exposure to military noise during military service by comparing two regressions of age-related hearing loss between groups with and without exposure to military noise. Cross-sectional observational study. Finally, 4079 subjects were included, among 10,286 data of men's audiogram from January 2004 to April 2010. We excluded repeated testers and any subjects who had other known external causes or had an asymmetric audiogram. We grouped subjects with exposure to military noise (N = 3163) and those without as the control group (N = 916). There was a significant effect of exposure to military noise at 4 and 8 kHz after controlling for the effect of age. The annual threshold deterioration rates were faster in the military noise exposed group than in the control group at 1, 2 and 4 kHz (p effect of exposure to military noise on age-related hearing loss showed an adding effect at 8 kHz and an accelerating effect in the frequency region from 1 to 4 kHz.

Degradation of natural habitats by roads: Comparing land-take and noise effect zone

International Nuclear Information System (INIS)

Madadi, Hossein; Moradi, Hossein; Soffianian, Alireza; Salmanmahiny, Abdolrassoul; Senn, Josef; Geneletti, Davide

2017-01-01

Roads may act as barriers, negatively influencing the movement of animals, thereby causing disruption in landscapes. Roads cause habitat loss and fragmentation not only through their physical occupation, but also through traffic noise. The aim of this study is to provide a method to quantify the habitat degradation including habitat loss and fragmentation due to road traffic noise and to compare it with those of road land-take. Two types of fragmentation effects are determined: structural fragmentation (based on road land-take only), and functional fragmentation (noise effect zone fragmentation, buffer using a threshold of 40 dB). Noise propagation for roads with a traffic volume of more than 1000 vehicles per day was simulated by Calculation of Road Traffic Noise (CRTN) model. Habitat loss and fragmentation through land-take and noise effect zone were calculated and compared in Zagros Mountains in western Iran. The study area is characterized by three main habitat types (oak forest, scattered woodland and temperate grassland) which host endangered and protected wildlife species. Due to topographic conditions, land cover type, and the traffic volume in the region, the noise effect zone ranged from 50 to 2000 m which covers 18.3% (i.e. 516,929.95 ha) of the total study area. The results showed that the habitat loss due to noise effect zone is dramatically higher than that due to road land-take only (35% versus 1.04% of the total area). Temperate grasslands lost the highest proportion of the original area by both land-take and noise effect zone, but most area was lost in scattered woodland as compared to the other two habitat types. The results showed that considering the noise effect zone for habitat fragmentation resulted in an increase of 25.8% of the area affected (316,810 ha) as compared to using the land-take only (555,874 ha vs. 239,064 ha, respectively). The results revealed that the degree of habitat fragmentation is increasing by considering the noise

Differential effects of white noise in cognitive and perceptual tasks

OpenAIRE

Herweg, Nora A.; Bunzeck, Nico

2015-01-01

Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy whe...

Noise pollution resources compendium

Science.gov (United States)

1973-01-01

Abstracts of reports concerning noise pollution are presented. The abstracts are grouped in the following areas of activity: (1) sources of noise, (2) noise detection and measurement, (3) noise abatement and control, (4) physical effects of noise and (5) social effects of noise.

Environmental noise pollution in the United States: developing an effective public health response.

Science.gov (United States)

Hammer, Monica S; Swinburn, Tracy K; Neitzel, Richard L

2014-02-01

Tens of millions of Americans suffer from a range of adverse health outcomes due to noise exposure, including heart disease and hearing loss. Reducing environmental noise pollution is achievable and consistent with national prevention goals, yet there is no national plan to reduce environmental noise pollution. We aimed to describe some of the most serious health effects associated with noise, summarize exposures from several highly prevalent noise sources based on published estimates as well as extrapolations made using these estimates, and lay out proven mechanisms and strategies to reduce noise by incorporating scientific insight and technological innovations into existing public health infrastructure. We estimated that 104 million individuals had annual LEQ(24) levels > 70 dBA (equivalent to a continuous average exposure level of >70 dBA over 24 hr) in 2013 and were at risk of noise-induced hearing loss. Tens of millions more may be at risk of heart disease, and other noise-related health effects. Direct regulation, altering the informational environment, and altering the built environment are the least costly, most logistically feasible, and most effective noise reduction interventions. Significant public health benefit can be achieved by integrating interventions that reduce environmental noise levels and exposures into the federal public health agenda.

Effects of occupational noise exposure on changes in blood pressure of workers

Directory of Open Access Journals (Sweden)

Hossein Ali Yousefi Rizi

2013-01-01

Full Text Available    BACKGROUND: In most industries, workers are exposed to loud noise. Noise is considered as a nonspecific biological stressor that have adverse effects on human physiology. It is associated with hypertension which is in turn one of the most important preventable risk factors of cardiovascular disorders. This study aimed to evaluate the effects of noise on changes of workers' blood pressure.    METHODS: This cross-sectional study was performed on 90 individuals who were exposed to noise at one of the industries in Isfahan, Iran. Noise levels (in dBA were measured by means of a sound level meter. Data was collected using a demographic questionnaire and physical examination. Blood pressure was measured by a sphygmomanometer at workplace. The collected data was analyzed by t-tests.    RESULTS: The workers aged 31.5 ± 5.2 years and were exposed to mean noise level of 97.5 ± 10.1 dBA which was significantly above the standard level (85 dBA.The relationships between blood pressure, heart rate, and noise level were not significant. However, Pearson’s correlation indicated systolic blood pressure to have significant correlations with age (correlation coefficient = 0.302 and work experience (correlation coefficient = 0.299.    CONCLUSION: Workers exposed to noise levels above the standard, especially in the metal industry but their blood pressures haven’t any associated with noise. it mention that any changes in blood pressure resulting from occupational noise are likely to be small, careful controls, large sample sizes, and long time exposure to noise would be take to identify significant effects.       Keywords: Noise Exposure, Blood Pressure, Young Workers, Cardiovascular Disease, Metal Industries

Combined Effects of High-Speed Railway Noise and Ground Vibrations on Annoyance.

Science.gov (United States)

Yokoshima, Shigenori; Morihara, Takashi; Sato, Tetsumi; Yano, Takashi

2017-07-27

The Shinkansen super-express railway system in Japan has greatly increased its capacity and has expanded nationwide. However, many inhabitants in areas along the railways have been disturbed by noise and ground vibration from the trains. Additionally, the Shinkansen railway emits a higher level of ground vibration than conventional railways at the same noise level. These findings imply that building vibrations affect living environments as significantly as the associated noise. Therefore, it is imperative to quantify the effects of noise and vibration exposures on each annoyance under simultaneous exposure. We performed a secondary analysis using individual datasets of exposure and community response associated with Shinkansen railway noise and vibration. The data consisted of six socio-acoustic surveys, which were conducted separately over the last 20 years in Japan. Applying a logistic regression analysis to the datasets, we confirmed the combined effects of vibration/noise exposure on noise/vibration annoyance. Moreover, we proposed a representative relationship between noise and vibration exposures, and the prevalence of each annoyance associated with the Shinkansen railway.