Ear injury from air bag deployment noise?

Data from animal exposures to impulse noise is reviewed and an auditory injury criterion is proposed. The criterion is based on A-weighted acoustic energy, normalized to an equivalent 8-hour exposure, for which a level of 92 dB is estimated to cause unacceptable permanent auditory injuries in 10% of the population. Auditory hazard of air bag noise was assessed by comparing recent fleet representative air bag noise data with four impulse noise occupational standards used in NATO countries and with the auditory injury criterion arising from this study. The data analysis indicates that air bag deployment produces intense noise that exceeds each of the current occupational standards for noise related ear injury. Dual air bag deployments produce peak sound pressure levels from 165 to 175 dB and A-weighted energies as large as 97 dB. The proposed auditory injury criterion, together with the observed distribution of energy levels from the air bags tested, suggests that air bag noise can produce permanent auditory injuries in about 1-2% of the deployments.