The reduction of gunshot noise and auditory risk through the use of firearm suppressors and low-velocity ammunition.
William J Murphy, Gregory A Flamme, Adam R Campbell and 6 others
PMID 29299940WHAT IT FOUND
Suppressors and low-velocity ammunition lowered measured gunshot noise at the shooter's ears.
The reductions were larger when both were used, but hearing protection is still recommended because no firearm-suppressor pair was shown hearing safe.
Key findings
01Both suppressors and low-velocity ammunition reduced sound levels at all microphone locations. At the left ear, the combined condition averaged 40 dB lower than the unsuppressed high-velocity condition, with an additional 6 dB reduction beyond the individual effects (95% CI: 2.5 to 11 dB).
02In the sound power study, the suppressor reduced total radiated sound power by 23 dB for the pistol with low-velocity ammunition and by 16 dB for the rifle with low-velocity ammunition. The reductions were 15 dB and 2 dB for high-velocity ammunition for the pistol and rifle, respectively.
03Peak-level reductions tended to be larger than energy-level reductions, so judging suppressors by peak level alone may overstate their effectiveness.
STILL TO COME
How it was doneWhat they found
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What it does not show
The suppressors tested were a convenience sample provided by the Michigan Department of Natural Resources and by an author, so they may not represent all suppressors. The guns tested do not necessarily represent many guns commonly used in recreational or occupational settings. Most guns tested used a bolt-action loading mechanism, so the results may not reflect semi-automatic guns that vent gas near the shooter's right ear. Measurements were made in open field conditions, so they do not show what happens near walls or other reflective surfaces where echoes can add to the hazard. The authors state that the limited numbers of firearms, suppressors, and environmental conditions are not enough to call any combination of gun and suppressor hearing safe.
The easy way to misread this
Do not conclude that a suppressor and low-velocity ammunition make firearm noise hearing safe or remove the need for hearing protection. The authors say hearing protection is still recommended, and the limited firearms and suppressors tested were not enough to call any combination hearing safe.