Auditory hazard from airbag noise exposure.

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.