Actual Effectiveness of Hearing Protection in High Level Impulse Noise

摘要

Current exposure limits for high intensity impulse noise contain factors forhearing protection which are based on very limited data. Recent studies in the U.S. and in France have provided new insights into the protection afforded by hearing protective devices. For impulses with an A-duration of approximately 3.0 ms, protection was found to be adequate for peak pressures up to 190 dB SPL for 6 impulses and 187 dB for 100 impulses. Protection was found to be adequate for 6 impulses with an A-duration of approximately 0.8 ms up to 196 dB SPL. For this A-duration, protection was adequate for 12 impulses up to 190 dB SPL and for 50 and 100 impulses at 187 dB SPL. The hearing protectors used in these studies were earmuffs with perforations in the cushions which provided essentially attenuation below 500 Hz. In a series of French studies, hearing protection was found be adequate for impulses produced by a variety of weapons with peak pressures ranging from 165 dB SPL to 180 dB SPL. These included small arms with A-durations less than 1.0 artillery with A-durations of approximately 3.0 ms and other weapons with durations between these extremes. A variety of insert hearing protectors (earplugs) was used in these studies. (AN).