It has come to our attention that noise levels associated with air bag deployment may result in occupants experiencing irreversible hearing loss. Laboratory studies have established the likelihood that an air bag peak acoustic pressure of 170 dB will induce harmful inner ear effects.1 In these air bag studies, the greatest hearing loss is in the inboard ear at 4000 Hz. We have now seen this pattern in patients exposed to air bag deployment acoustics. These patients showed the greatest hearing loss in the 3000- to 6000-Hz range. Since the loss occurs above the speech frequency range of 500 to 2000 Hz, it may not be immediately apparent to a patient. Audiologic testing would be useful in detecting such high frequency hearing loss. The injury to the ear, however, may show up as a ringing in the ear, or tinnitus, which some patients reported. Tinnitus is commonly associated with inner ear damage and is usually associated with frequencies above the speech frequency range. Thus, air bag deployment may not only cause hearing deficits but may also result in the onset of tinnitus.
Morris MS, Borja LP. Air Bag Deployment and Hearing Loss. Arch Otolaryngol Head Neck Surg. 1998;124(5):507. doi:10.1001/archotol.124.5.507