Improving speech intelligibility performance for aircraft maintainers by selecting an appropriate combination of hearing protection devices

Abstract

Aircraft maintainers work in hazardous noise environments throughout their career. Hazardous noise levels on the flight line vary, affecting the level of hearing protection required to reduce their risk of hearing loss and other hearing related disabilities. Current practice is to provide double hearing protection: a circumaural headset/earmuff with foam earplugs. This combination may provide an adequate amount of protection from aircraft noise, but the proper use of foam earplugs may degrade speech intelligibility (SI) performance. Due to this degradation, many maintainers fit the foam earplugs incorrectly in order to improve SI performance, therefore lowering the amount of protection provided. The objective of this study was to assess the noise attenuation and SI performance of a headset and filtered earplugs worn alone and in combination to provide a more appropriate recommendation of hearing protection devices. The filtered earplug can provide suitable levels of protection when worn alone or in combination with a headset (depending on the noise environment) and can provide adequate “hear through” capability for acceptable SI performance when communicating face-to-face (single hearing protection) or through the aircraft communication system (double hearing protection).