An analysis of noise-induced hearing loss in Army helicopter pilots.

Hearing loss in the aviation environment has been attributed to a variety of factors ranging from aircraft noise exposure to the aging process. Consequently, this study was conducted to determine the relative contribution of age, total flight hours, type of aircraft, and use of hearing protection to hearing loss in U.S. Army aviators. Information from a survey of the aviators in an aviation brigade was combined with audiometric records to create the data file. The final study group, 83% of the unit aviators, was evaluated for hearing loss using two criteria: 1) existing U.S. army standards, and 2) four empirical categories of significant threshold shift. Data analysis suggests that hearing loss is primarily a function of noise exposure as measured by total flight hours. Age was found to be a less significant factor; aircraft type had no significant effect. The results indicate that combination hearing protection appears to significantly lower the risk of hearing loss.