Noise control on military shooting ranges for rifles

Impulse noise from rifle shots on shooting ranges exposes trainers and trainees to a significant risk to their hearing. This study concerns the possibilities of controlling noise exposure during military shooting practice. Without any noise-control measures on open ground, the average noise exposure was 100 dB for a trainer and 110 dB for a trainee (LAeq5min), i.e. 80 dB for a trainer and 90 dB for a trainee over a day (LAeq8h). The noise peak values were 150–160 dB near the trainee and 120–150 dB near the trainer. The peak values of rifle shots were attenuated to 15–40 dB with hearing protectors, 18–28 dB with silencers, 10–15 dB with enlosures around the rifle and 1–10 dB with walls. The duration of the shots and the impulse energy attenuation were also studied. In a wooden shelter the noise exposure of a trainer was 0–12 dB higher than on an open range. When the shelter was covered with absorbent material, the noise energy was attenuated to 1–8 dB. Active hearing protectors would aid the teaching of trainees by keeping speech audible.