Abstract: Throughout the twentieth century, engineers have used increasingly sophisticated experimental and theoretical approaches to reduce the noise of machines, vehicles, aircraft, etc. Since the mid-1980s it has become apparent to manufacturers that it is insufficient simply to reduce overall noise levels. In most cases the noise of vehicles, appliances, etc, has been sufficiently suppressed that it no longer poses a hearing loss hazard after extended exposure, or interferes with speech, sleep and other activities of occupants. Other properties of the noise, in addition to its overall sound pressure level, such as loudness, frequency content, tonal components, impulsiveness, and level fluctuations may determine whether the quality of the noise is acceptable or not in particular circumstances. Product sound quality studies have been made on household appliances, air-conditioning systems, high speed trains, etc., although most attention has been paid to interior vehicle noise. This paper reviews the main properties of sound that are important in sound quality determination and includes some of the author’s own experimental evaluations of the sound quality of four automobiles.


Brief Biography of the Speaker:
Dr. Crocker has 45 years' research experience in the areas of experimental and theoretical acoustics, vibration and noise control. He was named Assistant Director/Acoustics of Purdue's Ray W. Herrick Laboratories in 1977, where he also conducted research on vehicle and machinery noise from 1969 to 1983. He has published over 350 technical articles and books in acoustics and vibration and noise control. He was a founding director of INCE/USA in 1971 and of International/INCE in 1974. Dr. Crocker was general chair of Internoise 1972 and the 1981 President of INCE/USA. From 1973 to 1994 he served as Editor-in-Chief of the international refereed publication: Noise Control Engineering Journal. He has also served as Editor-in-Chief of the four volume 2000 page Encyclopedia of Acoustics published by John Wiley and Sons in 1997 and the single volume Handbook of Acoustics in 1998. The Encyclopedia won the 1997 award of the American Association of Publishers for excellence in professional and scholarly publishing. He has served as Executive Director of IIAV since 1995 and Editor-in-chief of the International Journal of Acoustics and Vibration since 1996. His Handbook of Noise and Vibration Control was published by John Wiley and Sons in 2007. In the last 38 years Dr. Crocker has been principal investigator on over 70 research contracts for industry and government and has supervised over 50 graduate students. He currently has two three-year NASA contracts to study and predict spacecraft rocket exhaust noise at launch and the turbulent boundary layer and separated flow noise and oscillating shock pressure fluctuations on the NASA Orion/Ares space vehicle, which will replace the Shuttle Orbiter. Dr Crocker has three honorary doctorates from Bucharest and Craiova, Romania and St. Petersburg, Russia.