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Distinguished Lecture 1

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Binaural Hearing Mechanisms

Prof. Dr. H. Steven Colburn

Department of Biomedical Engineering and Hearing Research Center, Boston University, 44 Cummington Street, Boston, MA 02215, United States of America

H. STEVEN COLBURN, Ph.D., is the professor of Biomedical Engineering at Boston University , where he is also the Director of the Hearing Research Center . Prof. Colburn's degrees were all in Electrical Engineering and were all received from the Massachusetts Institute of Technology (MIT) in the 1960s.  Dr. Colburn was on the faculty at MIT for about ten years before he went to Boston University in 1980 as Chair of the Biomedical Engineering Department, a position that he held for ten years.  His research activities have been focused on the study of binaural hearing since graduate school. His laboratory combines modeling of physiological processing, empirical studies of human performance, and signal processing models that predict behavioral abilities from processing responses of neural populations.

The mechanisms of binaural hearing, both physiological and signal-processing mechanisms, are reviewed with an emphasis on the relationships between underlying mechanisms and functional benefits. The elements of the binaural hearing system start with peripheral processing of each acoustic input through narrowband filters, nonlinear rectification, and envelope extraction. Intermediate processing stages combines left and right information in each frequency band with short-time cross-correlation to estimate interaural time delays and a mechanism for interaural intensity weighting. The central processing stages combine information across time and frequency to form perceptions of sources of sound in the acoustic environment. The perceptual abilities of human listeners are discussed in terms of these processing stages. These abilities include classic binaural abilities in sound-source localization and binaural masking level differences as well as improved speech intelligibility in multiple-source and reverberant environments and spatial release from informational masking.

Distinguished Lecture 2

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Noise Sources and Virtual Noise Synthesis

Prof. Dr. Goran Pavić

National Institute of Applied Science,

20, avenue Albert Einstein, 60621 Villeurbanne , France

GORAN PAVIĆ, Ph.D., holds BSc in Mechanical Engineering and PhD in structural dynamics. He has worked in several R&D institutes before settling as a professor in vibration and acoustics at the National Institute of Applied Science in Lyon , France . His published works include studies of air-borne and structure-borne acoustical energy flow, experimental analysis and diagnostics of mechanical and fluid systems, modelling of sound radiation, analytical vibration modelling and source characterisation. His present interest is in methods of improving noise prediction results by p-fractional multiplication techniques.

The synthesis of noise of an industrial product can be done by sub-structuring it into its basic components. A particular sub-structuring method, the Noise Synthesis Technology (NST) offers such a possibility. It predicts the trends in the overall noise by combining data from the real source(s) with a simplified modelling of the main frame. The connectivity between the source(s) and the frame is ensured in NST by impedance coupling rules. The critical components are the noise sources which have to be characterized by measurements. The characterization techniques are not simple, but reveal a lot of useful information to the designer apart from providing the input data to the core NST. The simplified frame model has the advantage of being robust and easy to implement in the NST synthesis. The output of the synthesis is the noise level and the noise waveform for audible reproduction. The paper outlines the basics of the source characterization techniques and of NST approach.

Distinguished Lecture 3

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Microperforation Research for Sound Absorption and Noise Reduction

Prof. Dr. Jing Tian

Institute of Acoustics , Chinese Academy of Sciences,

21 Beisihuanxilu St. , Beijing 100080, China

JING TIAN, Ph.D., is currently a professor of the Institute of Acoustics , Chinese Academy of Sciences (IACAS), Beijing , China . He got his B.Sc. in 1982, M.Sc. in 1984, from Nanjing University . In 1991, he obtained his Ph.D. from IACAS. In 1984 - 1987, Tian was a Reseach Assistant, and then a Lecturer in Nanjing University . He was promoted to Associate Professor in 1992, and then Professor in 1995 in IACAS. Tian’s research interest is widely on environmental noise, noise and vibration control, active control systems and acoustic MEMS. He has accomplished over 40 research contracts for industries and the government as principal investigator, published more than 140 technical papers, and been awarded 5 academic prizes for his creative achievements in scientific research in the last 20 years. Tian is also a Fellow and the President of Acoustical Society of China, Chairman of Environmental Physics Committee, Chinese Society of Environmental Sciences, Chief Director of Committee of the Acoustical Standardization Technology of China, Fellow and Director of the International Institute of Acoustics and Vibration.

Microperforation is a special technology widely used in sound absorption and noise control. Microperated panels can be served as non-fibrous broadband sound absorptive materials, not only applied to general building acoustics and noise control engineering, but also to some extremely high temperature or high speed flow cases. When backed with layers of cavities, the panel can give effective sound absorption in several octaves in the low-frequency range. In jet noise control, well-designed micropores at the outlet of an air or steam jet nozzle can greatly reduce the noise radiation in audible frequency range, by 20 to even 60 dBA generally. In this paper, the acoustical behavior of microperations in sound field or at the source is introduced. Main research progress in the sound absorption mechanism and its practical applications in noise control are reviewed and discussed. The physical concepts of turning the sound energy into turbulence, and shifting the sound energy from audible frequency range to ultrasound frequencies, are very attractive and heuristic to the development of modern noise control technologies.

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Distinguished Lecture 4

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Evaluation and Control of Acoustical Environments in ‘Green’ (Sustainable) Office Buildings

Prof. Dr. Murray Hodgson

Acoustics & Noise Research Group SOEH-MECH,

University of British Columbia , Vancouver , BC , Canada

MURRAY HODGSON, Ph.D., graduated from Queen's University with a B. Sc. (Hons) in Physics and Mathematics.  He then obtained an M. Sc. in Sound and Vibration Studies and a Ph.D. in Acoustical Engineering from the Institute for Sound and Vibration Research (ISVR), University of Southampton , UK . Dr. Hodgson is currently Professor of Acoustics in the School of Environmental Health and in the Department of Mechanical Engineering at the University of British Columbia , Vancouver , Canada .  He is the Director of the Acoustics and Noise Research Group. Dr. Hodgson's main professional expertise and research interests are in architectural and engineering acoustics, with particular interests in the acoustics of industrial workshops and workrooms, computer room-prediction modeling, active and passive noise control, auralization, and in the evaluation, control and optimal design of acoustical environments in green buildings.  He teaches acoustics and noise control to undergraduate and graduate students in engineering, physics and architecture.  He has developed the PlantNoise and ClassTalk systems for the acoustical design of industrial workshops and classrooms.  He is the author of over 75 scientific articles and 200 conference papers in his field.

This paper discusses the increasing important issue of the acoustical design of 'green' (sustainable) buildings. Many 'green' buildings have unsatisfactory acoustical environments, according to their occupants. Work done at UBC to evaluate acoustical quality in 'green' office buildings and improve it by engineering control measures is reviewed. The problem of 'green'-building acoustics is introduced and its importance discussed. Details of the acoustical evaluation of six ‘green’ office buildings by occupant satisfaction surveys and acoustical measurements are presented, and their implications for the design of 'green' buildings considered. A detailed study of one naturally-ventilated 'green' building is discussed. Pre-treatment survey and measurement evaluation results are presented. It is concluded that inadequate noise isolation due to natural-ventilation openings is a big problem. The design and post-treatment evaluation of noise-control measures to improve the noise isolation in two situations is discussed. Finally, other ‘green’-building acoustical issues are noted, and conclusions are drawn as to where future work should be directed.