Noise-induced hearing loss among U.S. Air Force cryptolinguists.

BACKGROUND: Occupational noise-induced hearing loss remains epidemic in the U.S. Air Force (USAF) and aircrew members continue to be affected. This study examines noise-induced hearing loss (NIHL) observed among USAF cryptolinguists that is attributable to radio noise and attempts to determine whether the current USAF Hearing Conservation Program (HCP) adequately identifies NIHL. METHODS: Audiograms from 120 ground-based cryptolinguists were examined. Comparisons were made between 1998 audiograms and either the reference audiogram or the enlistment audiogram. To determine HCP effectiveness, results were compared with the USAF standard of 3% or fewer permanent threshold shifts (PTS) per year. RESULTS: Some 13.3% of the cryptolinguists experienced standard threshold shifts (STS) between their enlistment audiogram and their initial occupational (reference) audiogram; 9.2% experienced STS in 1998 as compared with their initial enlistment audiogram but only 6 of the 11 (54%) were detectable using the reference audiogram as the baseline. The frequency pattern of changes in hearing thresholds was characteristic for NIHL. CONCLUSIONS: The NIHL that occurs among cryptolinguists prior to performance of the reference audiogram, and the hearing threshold shifts that occur between the enlistment audiogram and the reference audiogram, may obscure future hearing loss in the population. The incidence of PTS appeared to exceed 3% when the enlistment audiogram was used. While this result was not significantly different from 3%, sample size limitations and data accuracy concerns warrant that this population be closely watched in the future.