Firearm suppressors reduce the muzzle blast of a gunshot through a series of baffles contained in a canister. The American National Standards Institute has no firearm suppressor testing standards. A recent NATO test standard, AEP 4875, ignores the contribution of the ground reflection at the shooter’s ears and is not representative of how firearms are typically fired. The aim of this study is to commence empirical development of a standard to assess the noise reduction of firearm suppressors for hearing conservation purposes. Fourteen firearms with and without a suppressor were evaluated with high velocity and low velocity (subsonic) ammunition. Twelve microphones were positioned in a ring 3 meters from the muzzle with 30° spacing and 1.5 meters above the ground. One microphone was positioned at 1 meter to the left of the muzzle and two microphones were positioned at 15 centimeters from the right and left ears of the firearm operator. The suppressors were effective in reducing the peak sound pressure levels between 3 and 28 dB and A-weighted equivalent energy (LAEQ) between 2 and 24 dB.

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