Hearing Protection Performance Evaluation of Active Noise Reduction Headsets Under High Intensity Noise Levels
High levels of noise within airborne or ground vehicles affect crew communication and prolonged exposure may lead to hearing-related damage if insufficient hearing protection is implemented. These acoustic environments are unique and varied based upon sources that generate tonal noise, broadband noise and impulsive noise.
One of the recommended solutions to mitigate the auditory risks of working in high noise intensity levels was to utilise hearing protectors with Active Noise Reduction (ANR) systems. Investigation was required in order to establish if performance degradation should be expected, the goal being to determine if further more comprehensive performance assessments would be required for hearing protectors with ANR.
In the present study, the four David Clark headset models e.g. 40600G-15, 40600G-20, 40750G-01 and H10-76XL were tested at various sound pressure levels such as 111 dB, 115 dB, 120 dB, 125 dB and 131 dB. As a result of this evaluation, it was observed that the performance of the four headset systems with ANR ON was repeatable and constant for noise excitation levels below 120dB.
However, as is demonstrated by the preliminary evaluation, the insertion loss performance of the four headsets with ANR systems ON, when exposed to unweighted overall sound pressure levels (OSPL) superior to 120dB, significantly degraded with each increasing noise level increment. It is also very important to mention that the passive hearing protection performance of the four headsets (ANR OFF) remained, as expected, consistent (no degradation observed) at all high intensity noise levels considered in this study.It will be shown that the performance of the hearing protectors with ANR electronic systems has to be consistently evaluated at various noise levels in order to accurately assess their expected performance in real life mission environment for personnel exposure to high intensity noise levels above 120dB.
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