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Noise Notes

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ISSN (Print) 1475-4738
Published by Multiscience

[31 journals]

Noise characteristics of twin-square slot jets
- Abstract: Acoustic measurements have been undertaken on two different twin square jet topologies. OASPL, spectra, directivity measurement and shock-cell visualization have been conducted to evaluate twin square jets in different edge-vertex orientations. The results indicate that twin square jets effectively suppress noise up to 4 dB in terms of OASPL and 6 dB in terms of screech tonal SPL compared to an equivalent single circular jet. The study promises that twin-jet topology could serve as an effective tool for noise suppression.
  Content Type Journal Article
  Category Research Article
  Pages 47-64
  
  DOI 10.1260/1475-4738.12.1.47
  
  Authors
  V. Boopathi Sabareesh, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India
  K. Srinivasan, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India
  T. Sundararajan, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 12
  Journal Issue Volume 12, Number 1 / March 2013
  PubDate: Tue, 14 May 2013 15:35:43 GMT
From the Ministries
- Abstract: From the Ministries
  Content Type Journal Article
  Category Research Article
  Pages 65-68
  
  DOI 10.1260/1475-4738.12.1.65
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 12
  Journal Issue Volume 12, Number 1 / March 2013
  PubDate: Tue, 14 May 2013 15:35:43 GMT
A Consolidated Theory for Predicting Rain Noise
- Abstract: This paper presents a theory for rain noise prediction, consolidating discussions of drop impact on a plate and resulting work on rain noise predictions that is found in the literature. An objective of the consolidated theory is a robust engineering model which does not rely on complex computational techniques or lengthy computer simulation. The model described is compared to measured data to establish accuracy and reliability.
  Content Type Journal Article
  Category Research Article
  Pages 3-26
  
  DOI 10.1260/1475-4738.12.1.3
  
  Authors
  Daniel Griffin, Marshall Day Acoustics, PO Box 5811 Wellesley Street, Auckland 1141, New Zealand
  Keith Ballagh, Marshall Day Acoustics, PO Box 5811 Wellesley Street, Auckland 1141, New Zealand
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 12
  Journal Issue Volume 12, Number 1 / March 2013
  PubDate: Tue, 14 May 2013 15:35:42 GMT
Comprehensive measurement in whole-body vibration
- Abstract: Accurate measurements of human response to whole-body vibration are essential to any conclusions about the health risks, discomfort, and assessment of suspension systems in vibration environments. While accelerometers are traditionally considered the main measurement tools in whole-body vibration studies, their measurements become questionable when they are attached to inclined surfaces or when the motion has coupled components in multiple directions. Current measurement correction methodologies are subjective and limited to simple cases. A comprehensive correction methodology using inertial sensors was used in this work to quantify human response under single fore-aft, single-vertical, and multiple-axis whole-body vibration of twelve seated subjects with supported-backrest and unsupported-backrest upright posture. Vibration files of white noise random signals with frequency content of 0.5-12 Hz and vibration magnitude of 1.8 m/s2 RMS were used in the testing. The results have shown considerable differences in the transmissibility measurements without proper correction. The work presented has the potential to standardize experimentation in whole-body vibration and make measurements more accurate and defined across labs.
  Content Type Journal Article
  Category Research Article
  Pages 27-38
  
  DOI 10.1260/1475-4738.12.1.27
  
  Authors
  Jonathan DeShaw, Department of Civil and Environmental Engineering, College of Engineering, The University of Iowa, Iowa City, IA 52242, USA
  Salam Rahmatalla, Department of Civil and Environmental Engineering, College of Engineering, The University of Iowa, Iowa City, IA 52242, USA
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 12
  Journal Issue Volume 12, Number 1 / March 2013
  PubDate: Tue, 14 May 2013 15:35:42 GMT
Environmental noise impact on school students' academic achievements
- Abstract: The aim of this paper is to investigate the relationships between environmental noise levels of schools and a set of academic achievement factors and also, to determine the noise exposure of schools. Secondary schools in Greater London were studied. Four academic achievement indicators were considered and five noise indicators were obtained after processing noise map data. The results show that in the studied schools, the environmental noise levels have almost no significant relationships with those academic achievement indicators. As expected, the secondary schools in Inner London are noisier than those in Outer London, with an average difference of 2dBA.
  Content Type Journal Article
  Category Research Article
  Pages 39-46
  
  DOI 10.1260/1475-4738.12.1.39
  
  Authors
  Hui Xie, School of Architecture, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
  Jian Kang, School of Architecture, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 12
  Journal Issue Volume 12, Number 1 / March 2013
  PubDate: Tue, 14 May 2013 15:35:42 GMT
Microphone array wind tunnel measurements of Reynolds number effects in high-speed train aeroacoustics
- Abstract: The present study focuses on the Reynolds number dependence of high-speed train aeroacoustic sound sources. To cover a wide range of Reynolds numbers the experimental investigations are carried out on a 1: 25 scale-model of the high-speed train Inter City Express 3 by conducting microphone array measurements in two wind tunnels. The latter are the Aeroacoustic Wind tunnel (AWB) of the German Aerospace Center (DLR) in Brunswick, providing nearly perfect acoustical conditions, and the Cryogenic wind tunnel (DNW-KKK) of the DNW (German - Dutch wind tunnels) in Cologne, allowing measurements at higher Reynolds numbers. Two types of sound sources with different characteristics at Reynolds numbers of up to Re = 0.46 × 106 have been identified by measurements in the AWB. It was found, that the aeroacoustic noise from the bogie section is dominant for frequencies f < 5 kHz and can be characterised by cavity mode excitation. Further, the pantograph is the dominant sound source above f = 5 kHz with an Aeolian tone characteristic. Additional aeroacoustic measurements have been conducted in the cryogenic wind tunnel DNW-KKK in order to analyse the Reynolds number dependence of the noise generated at the first bogie, for higher Reynolds numbers of up to Re = 3.70 × 106. The DNW-KKK admits varying the Mach and Reynolds numbers independently. These measurements reveal only a weak Reynolds number dependence of the noise source generated at the first bogie.
  Content Type Journal Article
  Category Research Article
  Pages 35-62
  
  DOI 10.1260/1475-4738.11.4.35
  
  Authors
  Andreas Lauterbach, German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology Bunsenstrasse, 10, 37073 Göttingen, Germany
  Klaus Ehrenfried, German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology Bunsenstrasse, 10, 37073 Göttingen, Germany
  Sigfried Loose, German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology Bunsenstrasse, 10, 37073 Göttingen, Germany
  Claus Wagner, German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology Bunsenstrasse, 10, 37073 Göttingen, Germany
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 4 / December 2012
  PubDate: Tue, 19 Mar 2013 18:36:13 GMT
Questionnaire about Low Frequency Noise measurements in rooms
- Abstract: Room modes at low frequencies generate large sound pressure level differences within enclosures. The resulting sound field is complicated and the sound pressure level measurements become very uncertain. Consequently, the measurements of environmental noise in dwellings, of occupational noise exposure, and of sound insulation of façades, are not accurate at low frequencies. A special measurement methodology exists in a few countries. Measurement methods aim to be accurate and reliable, but they can not determine, at the same time, both the existing and the experienced sound field. A questionnaire was created to gather opinions on how measurements should be performed from several experts with experience in low frequency noise measurements in rooms. Twenty-three experts took part in this survey. The results from the questionnaire are presented in this paper. Most participants considered it necessary to standardize a reliable measurement method, but there was no unanimity about what the method should be. The most controversial points of discussion were the locations where the measurements should be taken, and how the measured data should be analyzed. A brief discussion of these points is presented.
  Content Type Journal Article
  Category Research Article
  Pages 3-12
  
  DOI 10.1260/1475-4738.11.4.3
  
  Authors
  David Oliva, Finnish Institute of Occupational Health, Lemminkäisenkatu 14-18B, 20520, Turku, Finland
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 4 / December 2012
  PubDate: Tue, 19 Mar 2013 18:36:13 GMT
Airport noise insulation programs: The Spanish case
- Abstract: Noise pollution around airports is one of the most important problems in environmental acoustics. The incessant development of modern societies is continuously increasing the demand for air transport, and airports have to grow to adapt their operational capacity to the new requirements. On the other hand, the economic activity related to airports is closely linked to the expansion of built-up areas around them. Consequently, two completely incompatible land uses are forced to coexist, causing airport capacity to remain limited while the inhabitants do not cease to be annoyed by aircraft noise. Although there are several international initiatives setting the focus on the reduction of noise at the source, people living in residential areas around airports need urgent solutions. Among others, the implementation of sound insulation programs is one of the most widely-adopted solutions worldwide, as it allows a reduction of sound levels in the interior of dwellings, while the operational capacity of the airport remains unaffected. The definition and application of a sound insulation program is a very complex process that needs to manage several opposing factors: health, annoyance, airport capacity, economic costs of insulation measures … In this paper we describe the case of Spanish airport insulation programs. We set the focus on a concise description of the full process, from the creation of noise maps, to the checking of installed soundproofing measures, as carried out by the Spanish administration. As a result of this process, thousands of dwellings and houses have been acoustically insulated to meet indoor noise comfort criteria in Madrid, Mallorca and Malaga airports, among others.
  Content Type Journal Article
  Category Research Article
  Pages 25-34
  
  DOI 10.1260/1475-4738.11.4.25
  
  Authors
  C. Asensio, Universidad Politécnica de Madrid (CAEND), c/ Serrano, 144 - 28006 Madrid - Spain
  I. Pavón, Universidad Politécnica de Madrid (CAEND), c/ Serrano, 144 - 28006 Madrid - Spain
  M. Recuero, Universidad Politécnica de Madrid (CAEND), c/ Serrano, 144 - 28006 Madrid - Spain
  M. Ausejo, Universidad Politécnica de Madrid (CAEND), c/ Serrano, 144 - 28006 Madrid - Spain
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 4 / December 2012
  PubDate: Tue, 19 Mar 2013 18:36:13 GMT
Sound Pressure Levels in Rooms: A Study of Steady State Intensity, Total Sound Level, Reverberation Distance, a New Discussion of Steady State Intensity and Other Experimental Formulae
- Abstract: In this publication we include all, or almost all, the valid formulas of sound levels in different types of rooms. We will explain all the theoretical basis of each of them, starting with reflected intensity, both classical and revised theories, the total sound level and its uses in concert venues. We will also deal with empirical formulas mainly for classrooms, churches and religious buildings and industrial use. However, the main significance of this work is not only the wide range of formulas exposed but also that we have found the explanation of why the reverberation radius, or distance radius, cannot exist in the revised theory. This finding can help that the revised theory of M. Barron be slightly modified to apply it to any room for several uses, other than concerts
  Content Type Journal Article
  Category Research Article
  Pages 13-24
  
  DOI 10.1260/1475-4738.11.4.13
  
  Authors
  Higini Arau-Puchades, Arauacustica, C/Travessera de Dalt 118, 08024 Barcelona, Spain
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 4 / December 2012
  PubDate: Tue, 19 Mar 2013 18:36:13 GMT
From the Ministries
- Abstract: From the Ministries
  Content Type Journal Article
  Category Research Article
  Pages 63-68
  
  DOI 10.1260/1475-4738.11.4.63
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 4 / December 2012
  PubDate: Tue, 19 Mar 2013 18:36:13 GMT
From the Ministries
- Abstract: From the Ministries
  Content Type Journal Article
  Category Research Article
  Pages 71-74
  
  DOI 10.1260/1475-4738.11.1.71
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 1 / April 2012
  PubDate: Thu, 24 May 2012 20:33:00 GMT
Train Passengers Comfort with regard to Whole-Body Vibration
- Abstract: A case study was conducted to evaluate passengers' comfort on the Tehran-Andimeshk train in Iran. Hence, based on a=0.05, 91 passengers were selected. Whole-body vibration transmitted to the passengers was measured according to ISO 2631-1-1997. The crest factors in the the majority of wagons were below the 19 dB according to ISO 2631-1-1997 hence, the equal acceleration levels of the wagons were taken into consideration. The statistical relationships between 15 psychological and physiological disorders with age, gender, number of the trips and Aeq (equivalent acceleration level) were studied based on the questionnaires. The results revealed no statistical relationships between the health symptoms and age. Conversely, there was a significant statistical relationship between fatigue and gender. Also, sleeplessness and hearing disorders bother the passengers during the trips based on statistical analysis. Moreover, there were statistical relationships between studying with headache and nausea with eating. In addition, despite all 15 symptoms bothering the passengers during the trips, there was only a significant statistical relationship between Aeq (equivalent acceleration level) and anger. Hence, more factors must be taken into consideration to find the other reasons of passengers discomfort during the trips.
  Content Type Journal Article
  Category Research Article
  Pages 49-60
  
  DOI 10.1260/1475-4738.11.1.49
  
  Authors
  P. Nassiri, Department of Occupational Health, The School of Public Health, Tehran University of Medical Sciences, P.O Box 6446-14155, Tehran, Iran
  A. R. Koohpaei, Department of Occupational Health, The School of Public Health, Tehran University of Medical Sciences, P.O Box 6446-14155, Tehran, Iran
  H. Zeraati, Department of Epidemiology and Biostatistics, The School of Public Health, Tehran University of Medical Sciences, Iran
  P. Jafari Shalkouhi, Department of Environmental Engineering, Graduate School of the Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 1 / April 2012
  PubDate: Thu, 24 May 2012 20:33:00 GMT
Quantifying whole body vibration exposures in metropolitan bus drivers: an evaluation of three seats
- Abstract: The objective of this study was to evaluate three seats amongst a population of metropolitan bus drivers as they drove a standardized test route including city streets, old and new freeways, and a street segment containing ten large speed humps. Three comparisons were made: 1) comparing seats made by different manufactures (Seat 1 and Seat 2), 2) comparing seats with a standard foam (Seat 2) and silicone foam (Seat 3) seat pans, and 3) comparing WBV exposures based on road types. Whole body vibration (WBV) exposures were measured using a tri-axial seat pan accelerometer and the attenuation capabilities of each seat were evaluated by comparing the vibrations measured at the floor and seat of the bus. There were significant WBV exposure differences between the various street types, which were shown across all seat types. The city street and older freeway segments had the highest WBV exposures with both segments producing WBV exposures slightly above the action limit for Vibration Dose Value (VDV(8)). Relative to Seat 2, Seat 1 performed better at attenuating impulsive and shock related WBV exposures, however, neither seat performed significantly better when Average Vibration (Aw(8)) and VDV(8) WBV exposures were compared. In addition, no performance differences were seen between the standard foam (Seat 2) and silicone foam (Seat 3) seat pans. This study provided a unique opportunity to explore WBV exposures among bus drivers and potential ergonomic interventions in the way of seat options to reduce WBV exposures and potentially reduce workplace injuries.
  Content Type Journal Article
  Category Research Article
  Pages 61-70
  
  DOI 10.1260/1475-4738.11.1.61
  
  Authors
  Ryan P. Blood, School of Public Health, Department of Environmental and Occupational Health Sciences, Ergonomics Research Laboratory, University of Washington, Seattle, WA 98105, USA
  Peter W. Johnson, School of Public Health, Department of Environmental and Occupational Health Sciences, Ergonomics Research Laboratory, University of Washington, Seattle, WA 98105, USA
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 1 / April 2012
  PubDate: Thu, 24 May 2012 20:33:00 GMT
Acoustics for Symphony Orchestras; Status After Three Decades of Experimental Research
- Abstract: In 1978, one particular paper in JASA by Harold Marshall, D. Gottlob and H. Alrutz titled: "Acoustical conditions preferred for ensemble" inspired the author and other researchers to investigate the acoustic conditions experienced by musicians on concert hall stages. The research carried out since then has involved subjective assessment by musicians playing in simulated sound fields as well as in real halls; but also purely objective investigations have been reported. After one third of a century, it seems appropriate to summarize what we have learned and where we still need more knowledge. The paper will summarize major contributions to the field, discuss the differences in opinion in view of the limitations associated with different experimental approaches, and finally address the challenges related to meeting working environment requirements recently enforced by law in Europe for limiting the sound exposure levels of musicians.
  Content Type Journal Article
  Category Research Article
  Pages 3-26
  
  DOI 10.1260/1475-4738.11.1.3
  
  Authors
  Anders Christian Gade, Gade & Mortensen Akustik A/S, Copenhagen, Denmark
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 1 / April 2012
  PubDate: Thu, 24 May 2012 20:32:59 GMT
Evolution from ‘tabs’ to ‘chevron technology’ - a review
- Abstract: ‘Chevrons’, a sawtooth pattern on the trailing edge of exhaust nozzles, are being implemented on modern jet engines. The technology reduces jet noise for ‘separate-flow’ nozzles used on newer jet aircraft engines. The purpose of this paper is to describe the development of this technology, starting with studies of ‘tabs’ in the 1980's and 1990's. The tabs, essentially chevrons with more aggressive penetration, were studied in those early years with a focus on mixing enhancement in jets. Observations from experimentalists in connection with mixing enhancement and plume signature reduction suggested that there might also be a noise benefit. In the mid-nineties, these devices, with mild penetration to minimize thrust loss, were first seriously explored for aircraft engine noise reduction purposes. Prompted by a strong need for jet noise reduction, the study became a joint NASA/industry effort that ultimately matured the chevron technology to production by mid-2000's. The process is an example of how fundamental studies over decades eventually migrate to application but often take a concerted effort.
  Content Type Journal Article
  Category Research Article
  Pages 27-48
  
  DOI 10.1260/1475-4738.11.1.27
  
  Authors
  K. B. M. Q. Zaman, NASA Glenn Research Center, Cleveland, OH 44135, USA
  J. E. Bridges, NASA Glenn Research Center, Cleveland, OH 44135, USA
  D. L. Huff, NASA Glenn Research Center, Cleveland, OH 44135, USA
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 11
  Journal Issue Volume 11, Number 1 / April 2012
  PubDate: Thu, 24 May 2012 20:32:59 GMT
From the Ministries
- Abstract: From the Ministries
  Content Type Journal Article
  Category Research Article
  Pages 51-54
  
  DOI 10.1260/1475-4738.10.4.51
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 10
  Journal Issue Volume 10, Number 4 / December 2011
  PubDate: Tue, 03 Apr 2012 16:35:30 GMT
The Potential for Phononic Sound Diffusers (PSD)
- Abstract: Although periodic structures theory gave rise to sound diffusers almost 40 years ago, it has been only in recent years when several authors regarded the possible application of a particular kind of periodic structure, phononic crystals, in the field on room acoustics. This paper explores the possible application of periodic structures used as sound diffusers in rooms. Preliminary simulations, carried out with FDTD, shows that due to the inherent time spreading provided by a periodic structure, they can be used to reduce, or even to eliminate, pernicious effects associated with the low frequency modes of the room.
  Content Type Journal Article
  Category Research Article
  Pages 3-10
  
  DOI 10.1260/1475-4738.10.4.3
  
  Authors
  J. Redondo, Institut d'Investigació per a la Gestió Integrada de Zones Costaneres, Universitat Politècnica de València, C/Paranimf 1, 46730 Grau de Gandia, Spain
  Víctor Sánchez-Morcillo, Institut d'Investigació per a la Gestió Integrada de Zones Costaneres, Universitat Politècnica de València, C/Paranimf 1, 46730 Grau de Gandia, Spain
  Rubén Picó, Institut d'Investigació per a la Gestió Integrada de Zones Costaneres, Universitat Politècnica de València, C/Paranimf 1, 46730 Grau de Gandia, Spain
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 10
  Journal Issue Volume 10, Number 4 / December 2011
  PubDate: Tue, 03 Apr 2012 16:35:30 GMT
Hearing thresholds for low-frequency complex tones of less than 150 Hz
- Abstract: Hearing thresholds for low-frequency complex tones were measured to investigate effects of intensity and frequency differences between components and effects of the number of components on the detection of complexes. Complex tones comprised two tones, geometrically centered at 60 Hz, with frequency differences of 30, 60, 90, or 120 Hz. Sound pressure levels of the two tones were set to equal intensity or to equal sensation level. Additional threshold measurements were conducted for complex tones comprising 2-6 components at 25-145 Hz. A complex signal with multiple tones was detectable even if the levels of individual components were below the threshold. The improvement of complex signal detection varied greatly with the level difference and number of tones. Threshold levels for complex tones (in terms of level per component) decreased as the number of tones increased. Complex tones whose components have mutually similar frequencies were more detectable than those with separated components.
  Content Type Journal Article
  Category Research Article
  Pages 29-40
  
  DOI 10.1260/1475-4738.10.4.29
  
  Authors
  Jongkwan Ryu, National Institute of Advanced Industrial Science and Technology (AIST), Chuo 6-11, AIST Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
  Hiroshi Sato, National Institute of Advanced Industrial Science and Technology (AIST), Chuo 6-11, AIST Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
  Kenji Kurakata, National Institute of Advanced Industrial Science and Technology (AIST), Chuo 6-11, AIST Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
  Yukio Inukai, National Institute of Advanced Industrial Science and Technology (AIST), Chuo 6-11, AIST Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 10
  Journal Issue Volume 10, Number 4 / December 2011
  PubDate: Tue, 03 Apr 2012 16:35:30 GMT
Noise exposure of physical education and music teachers
- Abstract: For teachers, as well as for many other non-industrial categories of workers, noise exposure was for a long time considered a negligible risk. In the last decade, however, many researchers have investigated the problem. These have underlined that physical education and music teachers can subsist not only uncomfortable, but also unacceptable and risky noise exposures which can induce hearing problems and stress. The noise exposure levels are nevertheless very variable both for physical education teachers and for music teachers and depend on many factors. In this article an analysis of the noise exposure levels on 75 physical education teachers of 18 schools and of 9 music teachers of an academy of music are presented. The results show that a percentage of 20-25% PE teachers can reach a weekly noise exposure higher than 80 dB(A) while for 7 of the 9 music teachers the noise exposure during a normal working week can exceed the limit value of 87 dB(A).
  Content Type Journal Article
  Category Research Article
  Pages 41-50
  
  DOI 10.1260/1475-4738.10.4.41
  
  Authors
  Luigi Maffei, Built Environment Control Laboratory Ri.A.S., Second University of Naples, Abbazia di San Lorenzo ad Septimum, borgo San Lorenzo, 81031 Aversa (CE), ITALY
  Gino Iannace, Built Environment Control Laboratory Ri.A.S., Second University of Naples, Abbazia di San Lorenzo ad Septimum, borgo San Lorenzo, 81031 Aversa (CE), ITALY
  Massimiliano Masullo, Built Environment Control Laboratory Ri.A.S., Second University of Naples, Abbazia di San Lorenzo ad Septimum, borgo San Lorenzo, 81031 Aversa (CE), ITALY
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 10
  Journal Issue Volume 10, Number 4 / December 2011
  PubDate: Tue, 03 Apr 2012 16:35:30 GMT
Computation of bio-fluid sounds
- Abstract: A hybrid method is proposed for prediction of bio-fluid sounds at very low Mach numbers. The unsteady hydrodynamic flow field is computed by the incompressible Navier-Stokes equations (INS), while the sound field is obtained by solving the linearized perturbed compressible equations (LPCE) with sound sources represented by a total derivative of the hydrodyanmic pressure, DP/Dt. With the present INS/LPCE hybrid method, the vocal sound in human larynx and the buzz sound of bumblebee are computed with more clear understanding on the sound generation processes associated with their characteristic motions such as the self-sustained oscillatory motions of the vocal folds and the figure-eight motion of the flapping wings.
  Content Type Journal Article
  Category Research Article
  Pages 11-28
  
  DOI 10.1260/1475-4738.10.4.11
  
  Authors
  Youngmin Bae, Department of Mechanical Engineering, Korea University, Seoul, 136-701, Korea
  Young J. Moon, Department of Mechanical Engineering, Korea University, Seoul, 136-701, Korea
  Journal Noise Notes
  
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  ISSN 1475-4738
  Journal Volume Volume 10
  Journal Issue Volume 10, Number 4 / December 2011
  PubDate: Tue, 03 Apr 2012 16:35:30 GMT