Revolver Sound Level Comparison

[saleen322]

For years on multiple gun forums I read where someone would not use caliber X because it is just too loud if you had to use it in self defense without hearing protection. If you are like me, you wonder how much of the statements are research based and what is based on something someone else wrote or said without knowing the source of the information and then repeated over and over until it is viewed as fact. With a couple of free hours, six revolvers and a sound meter; we tried to get some more measurable data. The revolvers were selected to minimize difference in barrel length. The shortest barrel was 5.5" and the longest 7.5".

Some background on this, sound is attenuated to different degrees according to conditions present that include things like: indoors vs outdoors, hard surfaces (concrete, steel, etc) vs soft surfaces (carpet, long grass, snow, etc), the distance the meter is away from the sound and so on. The sound levels recorded only have value in comparing one revolver to another. Change any of these variables and you will likely get different numbers but the loudest gun will still likely be the loudest gun just the numbers will be different. The distance was chosen to be a safe place far enough away that the meter will not exceed its range. The test was conducted outdoors, meter operator and shooter standing on concrete and the target was 25 yards away with snow on the ground.

The ammo selected was common stuff similar to what you can get about anywhere. No boutique ammo was used. Surprises? The 10mm was a big surprise. The 327 was expected to be a much bigger spread louder than all else with internet lore and the shortest barrel length in the testing. The 45 Colt was a bit of a surprise as the standard load out of a 7.5" barrel was mid-pack and not the lowest reading. Conclusion: guns are all pretty loud (hahaha) and there is not the real big difference between them we expected. YMMV

 

[74A95]

Interesting data. Thanks for posting.

I think some additional information is required to help us understand the results. The specific ammunition that was used is necessary. Some loads might be wimpy versions for a given caliber, while others might be the most powerful version. We need that specific information to evaluate the data.

Also, for a more complete comparison several different loads could be used for each caliber. As suggested, light loaded versions for a caliber might produce different results than heavy loaded versions.

Another interesting test would be to use different powders for a given caliber to see how much effect that can have of sound. For example, XXX grains of Unique might produce more/less sound that YYY grains of H110, even if they produce the same velocity.

 

[bamaranger]

loud

I'd like to see data on 125 gr JHP in .357 mag, full power. That stuff seems terrible in any revolver I shoot it , and is a common SD load, or at least used to be.

The 10mm numbers don't surprise me. If factory ammo, the 10mm is notorious for being loaded down. Some factory loads barely exceed .40 S&W, if at all. Some loads do far better. A 203 gr slug will not allow much room for powder.

Also missing from the test is another load I'd like to see numbers on, any hot .40 S&W load. The .40 operates at high pressure as well.

 

[ruggyh]

I notice you did not include any of the high pressure rounds like 454 Casual and 460, 500 Smiths.

I think you find a considerable difference if you include them.

My research shows that the sound level goes up with pressure and velocity, not so much with caliber.

Just my observations

be safe
Ruggy

 

[74A95]

I see that the 327 Federal round produced more muzzle energy than the 10mm. I suspect that the 10mm ammo you selected doesn't represent the 10mm very well, and a 203 grain lead gas checked bullet is far from a common bullet for that round.

In fact, half your bullets are gas checked. Not exactly common stuff. How many 'factory' rounds used gas checked lead bullets? Anyone? I'm not sure that fits your, "The ammo selected was common stuff similar to what you can get about anywhere." description.

It sounds exactly like "boutique" ammo. Were any of the lead gas checked rounds "factory"? This is why we need the details on the ammo.

 

[gb_in_ga]

Note that those were all taken from long barrel weapons. Now, scale it back to the shorter barrel weapons that would be more likely to be used in indoors self defense. For instance, let's see what a .357 Mag does with a full power 125 gr out of a 4" revolver.

 

[tangolima]

The cylinder gap in a revolver affects sound level. I have an Enfield in wimpy 38 s&w with wide gap. It sounds pretty much like a 357 magnum.

-TL

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[saleen322]

Thanks for the comments. The barrel lengths were selected because that is what we have. We don't have any short barreled revolvers. We do have a 5.5" 41 mag, 5" 45 ACP, 4.2" 327 and a 8 3/8" 460 that we could have used as well but the smaller sample satisfied my curiosity. Since is was asked, 10mm around 200 grain going 1050 fps give or take is not hard to find.

It was interesting and we may do something more planned sometime in the future.

 

[Radny97]

Just remember that the decibel scale is not linear but exponential. Each three decibel points represents a doubling in volume. So the 357 is 67% louder than 9mm from a revolver. And 44 mag is double that of 357, etc.
In other words, these are a lot bigger differences than they initially appear.

 

[ms6852]

That is very interesting data you have and thank you for posting it. Wonder if you would consider putting the sound meter next to the shooter. My thought process is that I carry a 686 .357 in a 3" barrel , but have a FNX tactical .45 for home defense because the sound of the .45 is not as sharp as that of the .357 which the .357 appears to be louder in an enclosed environment. If the sound meter is placed next to the shooter it might register a different noise level to the shooter and helps the shooter understand how loud it actually is instead of registering the decibels from 15 ft away. This would seem to make a more accurate test in a defense scenario as you are measuring from arms length where the person is shooting his/her firearm.

Again I thank you for posting your finding...great job.

 

[stinkeypete]

I’m also interested in the profile of pressure intensity over time...

That is, a very abrupt initiation of pressure will be perceived as louder than a more “rounded” approach to peak.

Interesting stuff!
I am now wondering how one measures the sound level of an event that is very short duration!

Aha! I found mil-std 1474e section 4 as a good place to start

 

[BBarn]

Couple of notes. A 3dB increase corresponds to a doubling of power, not perceived volume. A 10dB increase in volume is perceived as twice as loud.

I suspect measuring sound levels produced by firearms can be difficult. A very "fast" sound measuring instrument would need to be used to accurately capture the peak sound level. And just how much the perceived sound level is affected by the peak level versus an average level would also need to be determined.

There is also the weighting of sound by the ear/brain over the frequency range of hearing. Some sound level measuring equipment "adjusts" for the human ear, while other equipment does not.

Not trying to undermine the effort or results. Just some things to keep in mind.

 

[tangolima]

Just remember that the decibel scale is not linear but exponential. Each three decibel points represents a doubling in volume. So the 357 is 67% louder than 9mm from a revolver. And 44 mag is double that of 357, etc.

In other words, these are a lot bigger differences than they initially appear.

Not quite.

Human hearing perception to loudness (volume) is logarithmic to sound power. dB is exponential so as to have linear scale of loudness. This is discovery of Alexander Graham Bell when he was fiddling with early telephony. He defined the lowest sound power perceivable to human ear as 0 Bel (Bell). dB (decibel) is 1/10 of a Bel. 30dB, quite conversation, is therefore 1000 times over 0dB (0 Bel) in terms of sound power.

The 10mm has 109dB, and the 9mm has 112dB. The latter has sound power 3 times over the former. But to the human ear is about 3% louder.

-TL

Sent from my SM-G930T using Tapatalk

 

[saleen322]

Wonder if you would consider putting the sound meter next to the shooter.

Thanks for the question. I was concerned it would be louder than our inexpensive meter could read. I think the meter tops out at 130 DB and I was thinking it would be more consistent if we keep a little room under that so that is why 15 feet away instead of right by the shooter.

The meter does have a hold max feature so it shows the peak reading for each shot. We shot 5 of each and took the average. This was something we did just to see how doable it was. We learned enough that we would be better on a future attempt. It was interesting though.

 

[44 AMP]

Sound from firearms can be measured and compared, but the sound our ears hear is like felt recoil. You can calculate decibels, or ft/lbs and have a standard for comparison on paper, but what people feel, and hear will vary widely with a host of additional factors that aren't easily plugged into equations.

Besides the distance from the ear, one thing I've noticed that makes a different in what we hear is the size of the hole in the pipe.

Big bores may be louder, but their big "boom" sounds don't match the (sometimes painful) "crack" of a high velocity .357.

Reflection matters too. Shoot your gun in a mountain valley and hear the sound rolling off the hills around you. Shoot that same gun in an apartment building hallway and its a VERY different experience!!

One of Hollywood's biggest uncorrected myths is actors "shooting" inside buildings and cars, even ARs and AKs, without any kind of hearing protection, and then being able to hear casual conversation or even whispers the instant the gunfire stops.

The real world doesn't work that way. Not even close.

 

[labnoti]

Where was the meter? 15 feet behind or to the side? My experience is that gunshot noise is very directional and one of the greatest dangers to hearing loss comes from immediately reflected sound. Firing a 12 ga shotgun off the top of a hill on a windy day hardly seems loud at all, but firing a .22LR in a small rocky canyon can be ear-splitting.

Also, for the sake of discussion, decibels are a measurement of sound pressure level for a given frequency. Sound meters use an algorithm to aggregate and "average" the sound pressure over different frequencies. The most common is "dBA" which gives greater weight to frequencies people's ears are more sensitive to. "dBC" gives a more even weighting to all the frequencies and therefore weighs low frequencies more than "dBA." Noise-induced hearing loss in humans usually starts around 4000 Hz (fairly high frequency), and the "dBA" weighting is probably the most meaningful for this purpose.

FWIW, I tried using a sound meter to take some similar measurements with fewer guns but a greater variety of cartridge characteristics. I wasn't able to get accurate readings because the sound meter wasn't fast enough. Based on my perception, the .357 Magnum with a 125 gr. bullet at almost 1700 fps was louder than anything bigger or slower. I don't have a .327.

Thanks for the data.

 

[Radny97]

Not quite.

Human hearing perception to loudness (volume) is logarithmic to sound power. dB is exponential so as to have linear scale of loudness. This is discovery of Alexander Graham Bell when he was fiddling with early telephony. He defined the lowest sound power perceivable to human ear as 0 Bel (Bell). dB (decibel) is 1/10 of a Bel. 30dB, quite conversation, is therefore 1000 times over 0dB (0 Bel) in terms of sound power.

The 10mm has 109dB, and the 9mm has 112dB. The latter has sound power 3 times over the former. But to the human ear is about 3% louder.

-TL

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Thank you. I don’t have expertise in this area, just knew that point weren’t linear but increased at a much greater degree


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