Military operational settings often feature hazardous noise sources that mandate the use of single or even double hearing protection devices (HPDs). Previous studies have mapped hazardous noise zones around helicopters, reinforcing the necessity of HPDs even at distances from the aircraft. However, awareness of such hazards and compliance with existing regulations does not ensure that worn HPDs provide adequate protection for individual users, particularly during sustained use and periods of activity/exertion that may impact HPD fitment. To enable the measurement of HPD effectiveness during sustained use, an in-ear exposure monitoring system was developed to measure sound pressure levels in the environment and within the ear canal beneath HPDs. This system was evaluated in an experimental field study using a UH60 Black Hawk helicopter as the operational noise source. The sound field was characterized using established methods, and participants were fitted with the in-ear exposure monitors under various HPD configurations. Participants underwent HPD fit testing before and after navigating the sound field, during which sound pressure data were collected. Questionnaires regarding subject experience were also collected. Results from this effort will provide insight into real-world HPD performance and support evidence-based suggestions for improvements to hearing conservation practices.
Podolski et al. (2025) studied this question.