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A while back I had to manage a long-term project that involved monitoring of noise levels. That’s when I learned about decibels, and there sure was a lot more to it than I realized. For gun folk, the word usually comes up in the context of muzzle brakes and suppressors. If any of you find the following info helpful then I’ve done my good deed for the day…
“Deci” is a prefix meaning one-tenth of something, and decibel is one-tenth of a Bel. A Bel is a unit of measure named in honor of Alexander Graham Bell. Since decibel is derived from a proper name the abbreviation for decibel has a capital “B”, as in “dB.”
Decibels are measured on a logarithmic scale which usually extends from 0 to 140 (it can go higher). The scale’s zero point is the threshold of what a human can barely hear, or barely not hear. As a logarithmic scale, each increase of 10 is ten-times more powerful. So 70 dB is ten-times more intense than 60 dB, 80 dB ten-times more than 70 dB, etc. In human terms, that 70 dB sound will seem about ten-times louder than 60 dB, and 80 dB will seem ten-times louder than 70 dB.
Most people think a decibel is limited to measuring acoustics, but it is also used as a unit of measure for perception, telephony, electronics, optics, videography, radar, antennae, bandwidth, amplitude/clipping, noise temperature, etc.
When a gun fires, three basic actions occur. Primer compound explosion, conversion of powder from a solid to gas, and resulting propulsion of a bullet through the barrel. All three of those actions make noise, and to use plain speak I’ll say there is both a “bang” and a “crack” noise.
The “bang” initially comes from ignition of primer compound (a small amount of high explosive chemicals), but more so from the sudden release of gas pressure out of the cartridge. Similar to a bottle of champagne making a low-level bang when uncorked, the sudden release of gas pressure from a cartridge can make a very loud bang. Suppressors are good at dampening the “bang” from gas pressure.
The “crack” occurs from the shock wave a bullet makes when it breaks the sound barrier. Usually that is around 1,125 feet per second (depending on atmospheric conditions). Most bullets travel at least that fast at the muzzle; even a 40-grain 22LR typically travels at 1,250 fps. This means even the diminutive 22LR bullet can “crack” as it breaks the sound barrier.
Since the “bang” and the “crack” happen so fast from the perspective of the shooter, they essentially combine to make a very loud noise – loud enough that ear damage could result. Even a single shot could result in some permanent hearing loss without ear protection.
“Quiet ammo” (aka subsonic ammo) achieves lower sound levels by both reducing the amount of gas pressure and keeping the bullet below 1,250 fps to prevent sound barrier “crack.” For example, 22LR ammo marketed as quiet might leave the muzzle at just 710 fps. In a semi-auto, quiet ammo may have pressure so low that it can’t sufficiently cycle the action. And importantly, best not to confuse “quiet” with silent. It is usually recommended that you still wear ear protection with quiet ammo (though others will argue that point, depending on the cartridge).
It’s the more typical loud firing noise that makes us interested in things like muzzle brakes, suppressors, and hearing protection. That is where decibels come in. (When it comes to muzzle brakes, we also need to differentiate between sound pressure and concussive blast, but that’s too much of a side track to go into here).
As a general point of reference, the little 22LR will produce around 134 dB. The 308 around 156 dB. The 45 ACP comes in at 157 dB. 30-06 around 159 dB. A 357 or 44 magnum around 164 dB. And a 12-gauge hits 165 to 170 dB. The shorter the firearm’s barrel, the higher the dB. To put those sound levels into perspective, a crowded restaurant is usually around 70 dB, a lawn mower is 90 dB, a chain saw is 100 dB, an emergency siren typically runs at 115 to 120 dB, and an aircraft carrier deck is around 140 dB. (See comparisons at https://www.m1911.org/loudness.htm)
Audiologists consider human hearing damage to begin at 85 dB. Studies by the American Speech-Language-Hearing Association (ASHA) have shown that people like us, firearm users, are more likely to experience hearing loss, usually at higher frequencies. You’ll notice that happening when you start losing the ability to distinguish sounds like “s,” “th,” or “v.” Right-handed shooters suffer more damage to their left ear, which is more in line with the muzzle, than their right ear. Shooters may also develop tinnitus, or permanent ringing in their ears.
When we’re at the range we’re all smart enough to wear hearing protection, right? Ear muffs will reduce noise between 15 to 33 dB. Look for the NRR number (noise reduction rating); higher is better. But consider, if you’re firing a magnum rifle or handgun around 160 dB or more, and your ear muffs reduce it down to 130 dB, that’s still hazardous to your ears. I recommend you wear earplugs in addition to muffs. And on top of that, a suppressor would help. The federal government should eliminate regulation of suppressors as a safety measure in order to allow more shooters to better protect their hearing.
However, what about when we’re hunting? If you’re like me you don’t wear hearing protection when hunting; I want to hear Mr. Bear when he’s in my neighborhood. Even if we’re not the person firing the gun, our hearing can be damaged by someone next to us who fires at game. Again, it takes only one shot to cause damage. I guess that’s just part of the price of hunting.
Audiologists are more interested in ear damage than just sound pressure, so they use “dBA” which is “A-weighted decibels.” dBA is intended to focus not only on what the human ear can actually hear, but also on how sound can damage the human ear. Consequently, many regulatory noise limits are specified in dBA. When we read about noise impacts from firearms, dB is not as helpful as dBA, but unfortunately there is very little (if any) data regarding firearms and dBA.
I’d be really interested to hear perspectives from an audiologist if we have one who is a GNG member.
(Note: The original post had an error, sort of, indicating 22 LR produced 152 dB. That is the correct dB level for a 22 LR pistol, but a 22 LR rifle is the better reference, and that is 134 dB. That dB level has been corrected above and the online reference source added for clarification.)
“Deci” is a prefix meaning one-tenth of something, and decibel is one-tenth of a Bel. A Bel is a unit of measure named in honor of Alexander Graham Bell. Since decibel is derived from a proper name the abbreviation for decibel has a capital “B”, as in “dB.”
Decibels are measured on a logarithmic scale which usually extends from 0 to 140 (it can go higher). The scale’s zero point is the threshold of what a human can barely hear, or barely not hear. As a logarithmic scale, each increase of 10 is ten-times more powerful. So 70 dB is ten-times more intense than 60 dB, 80 dB ten-times more than 70 dB, etc. In human terms, that 70 dB sound will seem about ten-times louder than 60 dB, and 80 dB will seem ten-times louder than 70 dB.
Most people think a decibel is limited to measuring acoustics, but it is also used as a unit of measure for perception, telephony, electronics, optics, videography, radar, antennae, bandwidth, amplitude/clipping, noise temperature, etc.
When a gun fires, three basic actions occur. Primer compound explosion, conversion of powder from a solid to gas, and resulting propulsion of a bullet through the barrel. All three of those actions make noise, and to use plain speak I’ll say there is both a “bang” and a “crack” noise.
The “bang” initially comes from ignition of primer compound (a small amount of high explosive chemicals), but more so from the sudden release of gas pressure out of the cartridge. Similar to a bottle of champagne making a low-level bang when uncorked, the sudden release of gas pressure from a cartridge can make a very loud bang. Suppressors are good at dampening the “bang” from gas pressure.
The “crack” occurs from the shock wave a bullet makes when it breaks the sound barrier. Usually that is around 1,125 feet per second (depending on atmospheric conditions). Most bullets travel at least that fast at the muzzle; even a 40-grain 22LR typically travels at 1,250 fps. This means even the diminutive 22LR bullet can “crack” as it breaks the sound barrier.
Since the “bang” and the “crack” happen so fast from the perspective of the shooter, they essentially combine to make a very loud noise – loud enough that ear damage could result. Even a single shot could result in some permanent hearing loss without ear protection.
“Quiet ammo” (aka subsonic ammo) achieves lower sound levels by both reducing the amount of gas pressure and keeping the bullet below 1,250 fps to prevent sound barrier “crack.” For example, 22LR ammo marketed as quiet might leave the muzzle at just 710 fps. In a semi-auto, quiet ammo may have pressure so low that it can’t sufficiently cycle the action. And importantly, best not to confuse “quiet” with silent. It is usually recommended that you still wear ear protection with quiet ammo (though others will argue that point, depending on the cartridge).
It’s the more typical loud firing noise that makes us interested in things like muzzle brakes, suppressors, and hearing protection. That is where decibels come in. (When it comes to muzzle brakes, we also need to differentiate between sound pressure and concussive blast, but that’s too much of a side track to go into here).
As a general point of reference, the little 22LR will produce around 134 dB. The 308 around 156 dB. The 45 ACP comes in at 157 dB. 30-06 around 159 dB. A 357 or 44 magnum around 164 dB. And a 12-gauge hits 165 to 170 dB. The shorter the firearm’s barrel, the higher the dB. To put those sound levels into perspective, a crowded restaurant is usually around 70 dB, a lawn mower is 90 dB, a chain saw is 100 dB, an emergency siren typically runs at 115 to 120 dB, and an aircraft carrier deck is around 140 dB. (See comparisons at https://www.m1911.org/loudness.htm)
Audiologists consider human hearing damage to begin at 85 dB. Studies by the American Speech-Language-Hearing Association (ASHA) have shown that people like us, firearm users, are more likely to experience hearing loss, usually at higher frequencies. You’ll notice that happening when you start losing the ability to distinguish sounds like “s,” “th,” or “v.” Right-handed shooters suffer more damage to their left ear, which is more in line with the muzzle, than their right ear. Shooters may also develop tinnitus, or permanent ringing in their ears.
When we’re at the range we’re all smart enough to wear hearing protection, right? Ear muffs will reduce noise between 15 to 33 dB. Look for the NRR number (noise reduction rating); higher is better. But consider, if you’re firing a magnum rifle or handgun around 160 dB or more, and your ear muffs reduce it down to 130 dB, that’s still hazardous to your ears. I recommend you wear earplugs in addition to muffs. And on top of that, a suppressor would help. The federal government should eliminate regulation of suppressors as a safety measure in order to allow more shooters to better protect their hearing.
However, what about when we’re hunting? If you’re like me you don’t wear hearing protection when hunting; I want to hear Mr. Bear when he’s in my neighborhood. Even if we’re not the person firing the gun, our hearing can be damaged by someone next to us who fires at game. Again, it takes only one shot to cause damage. I guess that’s just part of the price of hunting.
Audiologists are more interested in ear damage than just sound pressure, so they use “dBA” which is “A-weighted decibels.” dBA is intended to focus not only on what the human ear can actually hear, but also on how sound can damage the human ear. Consequently, many regulatory noise limits are specified in dBA. When we read about noise impacts from firearms, dB is not as helpful as dBA, but unfortunately there is very little (if any) data regarding firearms and dBA.
I’d be really interested to hear perspectives from an audiologist if we have one who is a GNG member.
(Note: The original post had an error, sort of, indicating 22 LR produced 152 dB. That is the correct dB level for a 22 LR pistol, but a 22 LR rifle is the better reference, and that is 134 dB. That dB level has been corrected above and the online reference source added for clarification.)
