Gun Blast Discussed: (ie: Decibel Rating)

[Tomcat47]

A post to another thread prompted this thread...Its long but informative to us all.

In Discussing pros/cons of .357 Magnum as HD ... I posted what I have always disliked about a .357 as Home Defense and Personal Protection (CCW) is the Decibels it produces!

(The following is personal - NOT what anyone should do without hearing protection - All firearms generally produce damaging Db ratings)

I have shot the following handguns with and without hearing protection at some point! ( and I am sure some not listed )

(.22 lr) (.25 acp) (.32 acp) (.38 special) (9mm auto) (.357 magnum) (.40 S&W) (.41 magnum) (.44 magnum) ..... (PS Never a magnum after I got out of mid 20's and realized how stupid it was!)

Now points of my own: (keep in my I DO NOT fire a gun without protection regularly...just have done it)
I usually carry a 9mm and use it for HD as well for the fact that I know personally I can fire a Beretta 92 outside without hearing protection and it does not phase me.. I can hear and talk and carry on conversation..no discomfort at all (even tho it is on the danger zone of Db scale) Indoors however is not so nice, but not debilitating, I can still hear after firing it...no definitive ringing? and not painful.

While some may not consider this obstacle in a defensive firearm...I DO! One factor in the proper outcome of a defensive situation is being able to observe what is going on around you...seeing and hearing!

I just bought a ported .357 and fired it once with inadequate ear plugs!
I fired it ONE time and was not happy-they did not block enough- after firing I looked and they were rated at 32Db - .357 is @ 164Db.. I was still over threshold of pain....nothing like pain to remind you to watch what you are buying - uncomfortable and muffled hearing for about the next 3 hours or so.
At least they did block enough to prevent ringing!

Anyway this is long, but important... Energy is sometimes a factor in these ratings as you will see. The caliber alone does not make a gun loud... For examples: My 9mm is not as loud as my .32 Beretta, My .40 S&W is louder than my .45 Acp 1911...My .22 Revolver 5" was fun to shoot while my Walther P22 is no fun without ear gear!

So here are some points of interest and you can run with the thread however you see fit:
Here's a short list of Environmental Noise decibel ratings:
(Normal breathing 10) (Interior home noise 50) (Crowded restaurant 70)
(City traffic 70) (Hearing Damage Possible 85) (Lawn mower 90) (Threshold of Pain 120) (Siren 120) (Jackhammer 130) (Jet engine at takeoff 140)

(.22 pistol 152) (12 gauge shotgun 156) (.45 ACP pistol 157) (9mm pistol 160)
(.357 Magnum revolver 164)

The decibel scale is a logarithmic scale, not a linear one. Each increase of 3 dB corresponds to sound that has twice as much energy (measured in pascals). Each 10 dB increase corresponds to a 10-fold increase in energy.

Loudness is a subjective thing. People might perceive a particular sound to be twice as loud when there is actually a 10-fold increase in energy. Most people cannot perceive differences in loudness of less than 3 dB.

Let's assume you have excellent electronic ear protection with an NRR rating of 29 dB. Let's use the quietest .22 caliber pistol, which has a noise level of 152 dB. Subtracting 29 from 152 still leaves you at a noise level of 123, this is still above the threshold of pain - 120 decibels. Like I said, all the calibers are too noisy.

So why do some of us still have excellent hearing after shooting for so many years? Because, gunfire is a complex, short-lived sound wave, and it doesn't travel as well through hearing protection as pure sustained tones do. The NRR rating on ear protection might actually be higher than the nominal 29 dB rating, in regards to gunfire. Yet, for "continuous" noise, the NRR rating may be reduced by as much as 50% of the nominal 29 dB rating.

So there you have it. Clear as mud.

In summary, the .45 produces less decibels than the 9mm, which produces less decibels than a full power 357 SIG. ALL of these calibers produce decibel ratings that can easily cause severe hearing loss, especially in enclosed environments. I highly recommend using one of the newer electronic ear protection devices. I know millions of people see a lot of pistol and rifle play on TV occurring outside and inside buildings where the good and bad guys don’t wear ear protection; and then they carry on regular conversations afterwards like nothing happened (no hearing loss or ringing ears, etc). Folks, that ain’t the way it is. Protect your ears for the long term. Don’t delude yourself into thinking that your ears are OK if you use a .45. Just ask a lot of old-timers who have broken ear safety rules during their lives. Be safe.

"Now hear This!", by Ralph Mroz, Combat Handguns, Sep 1998

 

[Coyote3855]

Could you run through that one more time? I may have missed something.

 

[Owen]

I haven't looked into this in a while, but I believe you cant simply subtract the NRR from the base sound.

I know you can't add sound pressure levels together. i.e. a 110 decibel sound plus a second 110 decibel sound gives you a 113 decibel sound, not 220dB. A 110 decibel sound, plus a second 113 decibel sound is something like 113.1 decibels.

I suspect the NRR ratings are similar, in other words,simple subtraction doesn't give the right number. It's probably fairly dependent on the magnitude of the sound being reduced.



Sent from my Transformer TF101 using Tapatalk

 

[Al Thompson]

While some may not consider this obstacle in a defensive firearm...I DO! One factor in the proper outcome of a defensive situation is being able to observe what is going on around you...seeing and hearing!

I've shot a lot of rifle cartridges at critters over the last 30 years and I have excellent hearing. My room mate in college ND'd a .30-30 in our apartment and suffered no major damage.

I'd rather choose a weapon based on effectiveness than noise levels. I do like 9mm, but decibel rating was pretty much ignored.

 

[Tomcat47]

Simple subtraction does apply to hearing protection...If you put in a set of earplugs that are rated to block 32 Db ... and you fire a .357 Magnum at 164 Db it will leave you open to 132 Db...

And I was not actually suggesting choosing based on Db it produces, but it is a real issue! Obviously Barrel length has an effect on Db. Like I said my Beretta 92 does not bother me and then my millennium is much louder!

And as article states there are electronic hearing protection devices that are available that make Db's entirely a non issue.

 

[Owen Sparks]

As I understand it, the level of noise is in preportionate to the pressure of the round rather than the volume of powder burned.

 

[Blackstone]

I once took my hearing protection off at an indoor range and forgot to put it back on. A 9mm going off in a small confined space quickly reminded me. It hurt a bit, but only for a short while and there was no ringing. I've no intention of finding out what a beefier round might be like indoors

 

[Stevie-Ray]

Attenuation ratings do not add either. Many of us that have "learned the hard way" through the years and are now victims of constant tinitus, double up with plugs and muffs, but the protection factors don't add. For example a set of NRR 29 dB muffs along with a set of NRR 33dB only give you an attenuation factor of ~40dB. Not an exact science, but you get the idea. At any rate, "doubling-up" is a must for some of us and I recommend it to all.

 

[KansasPaul]

I don't believe that the amount of decibels incorporates all of the sound impact - I feel that the frequency of the sound also contributes to the amount of "noise" produced from discharging a firearm. I shoot a lot of .357 and a lot of .44 mag - personally I find the sharpness of the .357 more irritating than the thump of the .44.

Now if I had an oscilloscope, a microphone and access to a large sound controlled room......

 

[Stevie-Ray]

Now if I had an oscilloscope, a microphone and access to a large sound controlled room......

......I still wouldn't remember how to use the oscilloscope, just like in DC/AC theory.

 

[DavidMS]

My Experience...

I double plug and find that the only guns that really are loud are .223s and .308/.30-06 and higher. Strangely enough, being directly behind the gun makes it much better...

 

[Tomcat47]

^^ I had a S&W .300 WM .... loved that rifle! They are really Howa's but anyway it was ported about 2" back.

That thing was so loud you came close to blacking out With hearing protection!

A friend of mine borrowed it and took it out west Elk hunting...he got one! But he told me it was late evening just about time to call the hunt when one stepped out a few hundred yards...he said he pulled the trigger and it was like looking into the sun through a scope and the loudest thing you could imagine at same time....did not know for 20 minutes or so if he even got it! lol

I cut the muzzle brake off and re-crowned the barrel! ...

 

[RTR_RTR]

I usually carry a 9mm and use it for HD as well for the fact that I know personally I can fire a Beretta 92 outside without hearing protection and it does not phase me.. I can hear and talk and carry on conversation..no discomfort at all (even tho it is on the danger zone of Db scale) Indoors however is not so nice, but not debilitating, I can still hear after firing it...no definitive ringing? and not painful.

________________________________________________________________

I just bought a ported .357 and fired it once with inadequate ear plugs!
I fired it ONE time and was not happy-they did not block enough- after firing I looked and they were rated at 32Db - .357 is @ 164Db.. I was still over threshold of pain....nothing like pain to remind you to watch what you are buying - uncomfortable and muffled hearing for about the next 3 hours or so.
At least they did block enough to prevent ringing!

9mm still comes in at over 150 dB... more like 160. I'm not saying that's not significantly softer than the .357, it is, but I don't really get the "no prob with no protection firing off 9mm, but .357 mag too much with plugs" logic

 

[Librarian]

The Howard Leight web site page of articles has a lot of interesting info - http://www.howardleight.com/hearing-protection/articles

 

[Owen Sparks]

I keep a pair of muffs hanging on my HD shotgun.

 

[Manco]

I haven't looked into this in a while, but I believe you cant simply subtract the NRR from the base sound.

It's quite never that simple in reality, but in the most basic sense, that's actually how it works. If it didn't, then hearing protection would not be very effective, based on the numbers.

I know you can't add sound pressure levels together. i.e. a 110 decibel sound plus a second 110 decibel sound gives you a 113 decibel sound, not 220dB.

That's because you're adding sounds in this case, while hearing protection multiplies it by a certain factor (less than 1, of course). Logarithms essentially change multiplication into addition, and powers into multiplication (and vice versa). So -3 dB is approximately the same as multiplying the power of a sound by 0.5. If an earmuff multiplies the power of sound by 0.001 (1/1000th), then its NRR rating should be 30 dB (negative value is assumed because it is protection or attenuation), and yes, you do subtract it from the loudness of the sound (in dB).

A 110 decibel sound, plus a second 113 decibel sound is something like 113.1 decibels.

It's actually about 114.76 dB (convert to a linear unit, add, then convert the sum back to dB), but point taken about the nature of logarithmic units nonetheless. The point I'm trying to make, however, is that hearing protection is different, at least when considering single devices.

By the way, not all logarithmic units are the same. For example, the Richter scale is very different from dB.

I suspect the NRR ratings are similar, in other words,simple subtraction doesn't give the right number.

It's sort of the same, but for different reasons. I'm not a professional or expert in the field, but I suspect that it has to do with the sound that gets around the device, going through the person's own body. This represents much of the sound that gets past any hearing protection device, and is accounted for in the NRR rating. The problem is that the same amount, pretty much, gets through regardless of how many devices you use together (as long as your body is exposed, anyway), which severely limits the amount of added protection.

Using an additional 30 dB device, for example, would attenuate the portion of sound that gets through the other 30 dB device by 30 dB (simple addition of their ratings), but whatever leaked around through the body before is still leaking in, making the overall protection only slightly better, rather than the full 60 dB we'd expect mathematically. Things would be different, I believe, for devices that completely encapsulate a person's body, but that's hardly practical for our purposes.

It's probably fairly dependent on the magnitude of the sound being reduced.

It depends on a lot of factors, including the frequency curve of the sound, but basically we can subtract the NRR rating when using a single device to get a decent estimate.

I've shot a lot of rifle cartridges at critters over the last 30 years and I have excellent hearing.

Outdoors, though, right? That makes a big difference, along with genetics, I strongly suspect.

My room mate in college ND'd a .30-30 in our apartment and suffered no major damage.

That was one shot, and maybe he has innately resilient hearing, too (some people do not).

I'd rather choose a weapon based on effectiveness than noise levels.

That's reasonable, but much like how the differences in noise level may not be much since all guns are LOUD, the differences in terminal effectiveness do not appear to be much, either, so people should go with whatever makes them the most comfortable.

As I understand it, the level of noise is in preportionate to the pressure of the round rather than the volume of powder burned.

It depends on both, I would imagine.

Attenuation ratings do not add either. Many of us that have "learned the hard way" through the years and are now victims of constant tinitus, double up with plugs and muffs, but the protection factors don't add. For example a set of NRR 29 dB muffs along with a set of NRR 33dB only give you an attenuation factor of ~40dB. Not an exact science, but you get the idea.

40 dB is probably close to the maximum that is physically possible for a device or set of devices that is merely mounted on a person's head. You cannot do significantly better because sound will still get through a person's skull and into their ears, regardless of the devices used. As explained above, attenuation ratings in dB don't add up, but for different reasons than multiple sounds. Doubling up still makes a significant difference, though, because 40 dB means 1/10th the loudness (in linear terms) of 30 dB, for example.

At any rate, "doubling-up" is a must for some of us and I recommend it to all.

I don't see how it could hurt, and it may very well help in long run--definitely worth the effort. If communication is an issue, then electronic earmuffs can help with that.

 

[Tomcat47]

9mm still comes in at over 150 dB... more like 160. I'm not saying that's not significantly softer than the .357, it is, but I don't really get the "no prob with no protection firing off 9mm, but .357 mag too much with plugs" logic

I Do not see the logic either....but its a fact! 9mm (out of Beretta - And that is nearly 5 inch Barrel) does not ring/hurt etc. (outdoors) Maybe 30 years around machinery has affected that tone for me??? And I do not make it a point to shoot ANY firearms with no hearing protection...(I want everyone to understand that)...

Maybe it is the "crack" that the magnum produces...which is a combined affect with pressure, that raises the bar when it comes to Db's.......

 

[Stevie-Ray]

Maybe it is the "crack" that the magnum produces...which is a combined affect with pressure, that raises the bar when it comes to Db's.......

If you're talking about supersonics, most 9mms loads are that as well. I find the report of a .45 ACP quieter than 9mm. I always figured it was because it was subsonic.

 

[Manco]

Maybe it is the "crack" that the magnum produces...which is a combined affect with pressure, that raises the bar when it comes to Db's.......

If you're talking about supersonics, most 9mms loads are that as well.

I doubt that sonic booms have much to do with the reports of various loads, especially since they are mostly heard as bullets whiz by somebody, as opposed to the shooter, who is directly behind.

The main differences between a .357 Magnum and 9mm load, regarding sound, are that the former is both louder and higher in pitch. This is because a typical .357 Magnum load generates more gas, which generally implies higher residual pressure at the muzzle. While these two calibers may have similar maximum internal pressures, the pressure in the barrel will have dropped more with 9mm by the time the bullet leaves the barrel because 9mm generates less gas.

I find the report of a .45 ACP quieter than 9mm. I always figured it was because it was subsonic.

It probably has a lot more to do with the fact that .45 ACP operates at significantly lower pressure in general, producing a less sharp (lower in pitch overall, as well as somewhat quieter) report.

 

[Telekinesis]

I doubt that sonic booms have much to do with the reports of various loads, especially since they are mostly heard as bullets whiz by somebody, as opposed to the shooter, who is directly behind.

I would think that they have at least a marginal impact on the sound level considering that if you take majority of the muzzle blast out of the equation (ie: use a suppressor) there is a significant difference in the sound level between supersonic and subsonic rounds.

I'm not sure exactly how that relates to firing unsuppressed firearms or weather the muzzle blast would effectively cover up the sonic boom (as perceived by the shooter), but I know that when using a suppressor, a shooter can definitely hear the difference between supersonic and subsonic. Its not just something that is heard down range.

 

[Stevie-Ray]

I'm not sure exactly how that relates to firing unsuppressed firearms or weather the muzzle blast would effectively cover up the sonic boom (as perceived by the shooter), but I know that when using a suppressor, a shooter can definitely hear the difference between supersonic and subsonic. Its not just something that is heard down range.

And try this. Load a 9mm to 1000 fps and one to 1150 fps and shoot both. Not too much difference in speed, yet the difference in report is staggering. We've done this before and there is a marked difference in supersonic ammo reports. I've noticed it mostly in 10mm, where wimpy loads sound like .45 ACP, but good loads, well.....

 

[Manco]

I would think that they have at least a marginal impact on the sound level

I'm sure there is some impact, which is why I didn't speak in absolutes.

considering that if you take majority of the muzzle blast out of the equation (ie: use a suppressor) there is a significant difference in the sound level between supersonic and subsonic rounds.

Relatively speaking, the difference would seem bigger without the muzzle blast--makes sense to me.

I'm not sure exactly how that relates to firing unsuppressed firearms or weather the muzzle blast would effectively cover up the sonic boom (as perceived by the shooter), but I know that when using a suppressor, a shooter can definitely hear the difference between supersonic and subsonic. Its not just something that is heard down range.

Right, which is why I said "mostly." However, this is basically moot because so many 9mm loads are supersonic like the .357 Magnum loads they were being compared to.

And try this. Load a 9mm to 1000 fps and one to 1150 fps and shoot both. Not too much difference in speed, yet the difference in report is staggering. We've done this before and there is a marked difference in supersonic ammo reports. I've noticed it mostly in 10mm, where wimpy loads sound like .45 ACP, but good loads, well.....

Hmmm...maybe the difference is more than I had thought, or ever noticed because admittedly I've never paid specific attention to how the effect of sonic booms compare to differences in muzzle blast in terms of magnitude. All I'm reasonably certain of is that when both loads are supersonic, the amount of gas that is generated makes a big difference in the pitch and loudness of the blast. I guess they're both significant factors, then (unless both loads are subsonic or supersonic).

The main points I was trying to make were that equal maximum internal pressure does not necessarily imply equal pressure exiting the muzzle (an all too easy assumption to make, I think), and the effects this can have on the sound that results.