Prospective measurements of hearing threshold during military rifle training with in-ear, protected, noise exposure monitoring

J Acoust Soc Am. 2022 Oct;152(4):2257. doi: 10.1121/10.0014700.

Abstract

Although a causal relationship exists between military occupational noise exposure and hearing loss, researchers have struggled to identify and/or characterize specific operational noise exposures that produce measurable changes in hearing function shortly following an exposure. Growing evidence suggests that current standards for noise-exposure limits are not good predictors of true hearing damage. In this study, the aim was to capture the dose-response relationship during military rifle training exercises for noise exposure and hearing threshold. To capture exposure, a wearable system capable of measuring impulse noise simultaneously on-body and in-ear, behind hearing protection was used. To characterize hearing threshold changes, portable audiometry was employed within 2 h before and after exposure. The median 8-h time-weighted, protected, free-field equivalent in-ear exposure was 87.5 dBA at one site and 80.7 dBA at a second site. A significant dose-response correlation between in-ear noise exposure and postexposure hearing threshold changes across our population ( R = 0.40 , p = 0.0281) was observed. The results demonstrate an approach for establishing damage risk criteria (DRC) for in-ear, protected measurements based on hearing threshold changes. While an in-ear DRC does not currently exist, it may be critical for predicting the risk of injury for noise environments where protection is mandatory and fit status can vary.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Auditory Threshold / physiology
  • Hearing
  • Hearing Loss, Noise-Induced*
  • Humans
  • Military Personnel*
  • Noise, Occupational* / prevention & control
  • Occupational Exposure*
  • Prospective Studies