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Noise attenuation of communication hearing protectors against impulses from assault rifle.

The noise attenuation values of commercial and military versions of earmuffs were measured using a Finnish assault rifle (RK762) as the sound source. The C-weighted peak level at the entrance of the left ear of the shooter was 156 dB (SD 1.0 dB; n = 25 shots). The noise was analyzed both outside and inside ear muffs on military volunteers on an open shooting range. All the earmuffs attenuated the C-weighted peak level to a value of less than 135 dB, which is less than the proposed values recommended by hearing damage criteria. Communication hearing protectors seem to function and attenuate sufficiently against the peak levels of the impulse noises used in this study.