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Nov 1999

Volume 106, Issue 5, pp. 2321-L52

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Auditory hazard from airbag noise exposure

G. Richard Price and Joel T. Kalb

J. Acoust. Soc. Am. Volume 106, Issue 5, pp. 2629-2637 (1999); (9 pages) | Cited 1 time

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Airbag deployment includes very intense acoustic stimulation, yet almost no tests of auditory hazard have been done with real ears. Therefore 32 anesthetized cats, positioned at the driver and passenger locations in a pickup truck, were exposed in pairs to one airbag deployment (electrically initiated). Hearing was tested at 1, 2, 4, 8, and 16 kHz by evoked-response audiometry just before exposure, immediately after and at 1 month and 6 months. Exposure conditions included doors open, compartment closed, and closed compartment sealed with tape: seven exposures to passenger bag only and nine to driver and passenger bags. Peak pressures ranged from 167 to 173 dB with unweighted energies as high as 4000 J/m2 (or 8 hr LEQA=95.5 dB). The immediate threshold shift averaged 60 dB at 4.0 kHz that resolved to an average permanent shift of 37 dB. By extrapolation, these data from cats may indicate that susceptible human ears risk permanent hearing loss from airbag noise. © 1999 Acoustical Society of America.
Show PACS
43.50.Qp Effects of noise on man and society
43.66.Ed Auditory fatigue, temporary threshold shift
43.64.Wn Effects of noise and trauma on the auditory system

Sound field modeling in streets with a diffusion equation

J. Picaut, L. Simon, and J. Hardy

J. Acoust. Soc. Am. Volume 106, Issue 5, pp. 2638-2645 (1999); (8 pages) | Cited 16 times

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By assuming that the surface irregularities of the building facades are adequate to produce diffusion in streets, a diffuse sound field model using the mathematical theory of diffusion is used to predict the sound propagation and its reverberation in rectangular streets. This model, developed to predict the sound field in rooms with diffusely reflecting boundaries, is applied in this paper to urban acoustics. A 3D diffusion equation is derived for the sound energy density and solved for time-varying sources and in steady state. A diffusion parameter is introduced to characterize the amount of diffusion in the street. An exchange coefficient depending on the absorption coefficient is also used to take into account the wall absorption. When the diffusion coefficient is rightly chosen, the predicted reverberation times and sound attenuations are in accordance with measurements in a scale model of a street. © 1999 Acoustical Society of America.
Show PACS
43.50.Vt Topographical and meteorological factors in noise propagation
43.20.Fn Scattering of acoustic waves
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
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