Citation

Nixon CW. Proc. Am. Assoc. Automot. Med. Annu. Conf. 1970; 14: 121-134.

Copyright

(Copyright © 1970, Association for the Advancement of Automotive Medicine)

DOI

unavailable

PMID

unavailable

Abstract

Personal restraint systems employing the principle of rapidly expanding air bags show promise of providing greater protection of occupants during motor vehicle impact than any other system or technique currently in use. On inflation, these systems generate an intense acoustic impulse which may or may not constitute a potential hazard to the auditory systems of vehicle occupants. This study evaluated the potential acoustic hazard of the impulsive noise generated inside an automobile by inflation of one rapidly expanding air-bag personal crash protective system. Widespread use of this system in vehicles would result in an average exposure of about one or two impulses over a lifetime for those persons exposed. The acoustic impulse is characterized by a medium duration of 21 ms ec, median rise time of 5 ms ec and median peak pressure level of 168 dB. Ninety-one volunteers experienced the single intense impulse without hearing protection and their pre-and post- exposure audiometric and otologic examinations provided measures of auditory responses. Otologic effects on the drum membrane were negative. No discomfort or aural pain was reported. About 50% of the subjects and 35% of the ears experienced some temporary threshold shift with 65% of the ears recovering within 24 hours. Many subjects reported short duration tinnitus. Results indicate that the impulsive noise is very loud; however, the probability of irreversible harm to the auditory systems of vehicle occupants may be considered to be extremely small.