to the editor: Exposure to high noise levels associated with air bag deployment during an automobile accident may result in irreversible hearing loss. Laboratory studies have established that peak acoustic pressure of 170 dB produced during air bag deployment can induce harmful inner ear effects.1 In these air bag studies, the greatest hearing loss has occurred at 4,000 Hz.
In my practice, I have seen this pattern of hearing loss in patients exposed to air bag deployment. These patients showed the greatest hearing loss in the range of 3,000 to 6,000 Hz. Since the loss occurs above the speech frequency range of 500 to 2,000 Hz, it may not be immediately apparent to the patient; audiologic testing is required to detect hearing loss in this range.
However, the injury to the ear may manifest as tinnitus, which some of my patients have reported. Tinnitus is commonly caused by damage to the inner ear and is usually associated with hearing loss in 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. Other presenting complaints include loudness intolerance, dizziness or a sensation of stuffiness in the ear.
Establishing the cause-and-effect relationship between air bag noise exposure and hearing loss is facilitated when preaccident audiology results are available.
Physicians, other health care professionals and emergency department staffs should be cognizant of the possibility of yet another morbidity associated with air bag deployment. Patients who have been in a motor vehicle accident should be queried about air bag exposure and any noticeable change in hearing or onset of tinnitus.