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PostPosted: Thu Jun 27, 2019 9:23 pm 
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Location: Southern Gulf Islands, Beautiful British Columbia, Canada
Hello everyone!

Thought I'd start a new thread for interest sake with these Airgun Velocity versus Noise test results performed for another member contemplating the purchase of a Benjamin Marauder:

SPL /FPS data on the Benjamin Marauder First Gen. As it was a rainy day I performed these tests indoors, using a sound pressure meter and my Pro Chrono DLX. SPL (Sound Pressure Level) readings are relative to reflections off floors, ceiling and walls. I'm certain these numbers would drop when taken outdoors with same test parameters. As my M-Rod is regulated, 750 FPS is the maximum velocity possible with that particular rifle.

SPL Readings are standard A-weighted taken @ 1 meter parallel to muzzle.
.22 Calibre, 18.13 Gr JSB Exact Heavy Pellets

Velocity in FPS vs SPL in decibels, Standard A-Weighted.

394 / 97.2 db
447 / 98.6 db
498 / 100.5 db
558 / 101.5 db
599 / 102.2 db
619 / 102.5 db
663 / 102.6 db
689 / 102.7 db
701 / 102.9 db
710 / 103.6 db
722 / 103.7 db
736 / 102.9 db
750 / 103.1 db

For every 3 db difference, perceived volume to the human ear is either halved or doubled.
Example; 103.6 db @ 710 FPS is twice as loud as 100.5 db @ 498 FPS
It is clear from these results that FPS and SPL go hand in hand. To put this in perspective, I repeated the same test on my Modified Cometa Orion, which is one of the noisiest air guns I own ...... @ 930 FPS, the Spanish made rifle spits out a whopping 105.2 db of compressed air! That's almost double again the volume level of the M-Rod @ 701 FPS! Hearing protection is an absolute must in this sport1

Cheers! Avianmanor


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PostPosted: Thu Jun 27, 2019 10:58 pm 
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Very informative, Aaron.
I'm not sure if I've ever seen such an experiment before.
Not nearly as loud as a rock concert, but far louder than your lawnmower.
Seems to me anything above 80-90 db is considered to be potentially harmful


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PostPosted: Wed Jul 03, 2019 4:46 am 
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Some good data! Considering that a "good" suppressed .22LR would be in the 115 dB region, even if it's quite loud for an air rifle it's still pretty quiet.

That being said, I don't think the numbers alone are sufficient for a real comparison on what is actually heard, and a powerful pneumatic generally will be perceived to be louder than a properly suppressed small caliber powderburner because the sudden release of pressurized gas vis a vis gasses generated by rapid heating in a chemical reaction is not quite the same mechanism.

I remember a Small Arms Review article about the Welrod pistol:

Quote:
Although the sound meter as an objective measurement is an important benchmark, it does not tell the entire story. There are a number of air (pellet) pistols with similar sound levels and some integrally suppressed .22 rimfire pistols with a slightly lower sound level. The subjective evaluation of the Welrod is that it makes less noise than these other weapons. Part of the reason is the locked breech. Although left-of-muzzle measurements of the .22-rimfire weapons may meter a lower sound level, subjectively they are louder due to right-hand ejection port noise. Further, the Welrod, with its wipes, significantly changes the sound characteristic with elimination of virtually all the higher frequency sounds. The sound of the Welrod being fired in a quiet location is almost imperceptible at 15 feet. In a noisy environment and with the muzzle in actual contact with the intended target, it would be inaudible even to the operator.


Edmonton<500 wrote:
Not nearly as loud as a rock concert, but far louder than your lawnmower.
Seems to me anything above 80-90 db is considered to be potentially harmful


I believe there's a distinction made between the continuous sounds of concerts and heavy equipment etc. and the brief pulse of a muzzle report.


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PostPosted: Wed Jul 03, 2019 9:09 am 
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Edmonton<500 wrote:
Not nearly as loud as a rock concert, but far louder than your lawnmower.
Seems to me anything above 80-90 db is considered to be potentially harmful

PZAM wrote:
I believe there's a distinction made between the continuous sounds of concerts and heavy equipment etc. and the brief pulse of a muzzle report.


Thanks for the additional info PZAM -very interesting indeed! Hearing damage is a cumulative thing: Damage = SPL over Time. However, I believe one time events can also cause permanent hearing loss which may not be apparent until years later. I can remember more than one live rock concert which left my ears ringing several days later, now years later, I have tinnitus. When a person's ears ring days after an SPL event, there must be some serious injury going on. Conversely, low level long term exposure, like background noise in the workplace, can be just as damaging as short bursts of SPL at excessive level, like firearm reports. I've used hearing protection in my workplace and around firearms for the past 30 years, and although I believe this has prevented further hearing loss, the damage done in the earlier years of my life is permanent, and there is no going back to fix that.

Here's an interesting link which may help to put things in perspective: http://www.sengpielaudio.com/Permissibl ... reTime.htm
I implore all members, especially younger people who may be exposed to high SPL levels on a more regular basis, please please please, protect your hearing at all times!

Avianmanor

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PostPosted: Fri Jul 05, 2019 11:21 pm 
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Location: Vancouver BC
Fun fact about Sound Pressure Level meters: they are most sensitive to 1kHz.
They are tuned to pick up a Bellcurve shaped response from about 630hz to 4kHz centered at 1kHz. The human ear is also most sensitive to 1kHz, the center of the audio spectrum.

This is how guns can have different timbers but rate the same on the SPL meter.

the alternative to an SPL meter is a spectrum analyzer which measures the amplitude of 31 frequencies across the spectrum

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PostPosted: Sat Jul 06, 2019 9:45 am 
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PZAM wrote:
I believe there's a distinction made between the continuous sounds of concerts and heavy equipment etc. and the brief pulse of a muzzle report.


Yes you can go deaf/hearing damage, over a single muzzle report. I got considerable hearing damage. I was shooting indoors, and next to me was a guy shooting hot loads 357. I sneezed, ended up covering my mouth and nose, which forced a ear plug out, as the guy fired a foot away ( was a divider ) But that rang for months.

But there been a few punk rock concerts. But 12 years in the forces, subjects you to alot of loud noises. Loud un insulated/sound proof cabs vehicles, 84mm, grenades, shooting. Foam plugs don't help much, or sometimes didn't have time to throw in plugs.


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PostPosted: Sat Jul 06, 2019 10:38 am 
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leadslinger wrote:
PZAM wrote:
I believe there's a distinction made between the continuous sounds of concerts and heavy equipment etc. and the brief pulse of a muzzle report.


Yes you can go deaf/hearing damage, over a single muzzle report.

Anecdotal eveduence olny, but a work buddy recently told me his dad lost hearing by firing off a few rounds under a tin roof shed. He's not BS guy so I take his word. Dad went under the roof able to hear, came out deaf.
Especially for older folk, hearing can be lost in a single loud event.

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PostPosted: Wed Aug 28, 2019 8:39 pm 
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Joined: Thu Sep 01, 2005 12:41 pm
Posts: 122
Location: Montreal
Avianmanor wrote:
Hello everyone!

Thought I'd start a new thread for interest sake with these Airgun Velocity versus Noise test results performed for another member contemplating the purchase of a Benjamin Marauder:

SPL /FPS data on the Benjamin Marauder First Gen. As it was a rainy day I performed these tests indoors, using a sound pressure meter and my Pro Chrono DLX. SPL (Sound Pressure Level) readings are relative to reflections off floors, ceiling and walls. I'm certain these numbers would drop when taken outdoors with same test parameters. As my M-Rod is regulated, 750 FPS is the maximum velocity possible with that particular rifle.

SPL Readings are standard A-weighted taken @ 1 meter parallel to muzzle.
.22 Calibre, 18.13 Gr JSB Exact Heavy Pellets

Velocity in FPS vs SPL in decibels, Standard A-Weighted.

394 / 97.2 db
447 / 98.6 db
498 / 100.5 db
558 / 101.5 db
599 / 102.2 db
619 / 102.5 db
663 / 102.6 db
689 / 102.7 db
701 / 102.9 db
710 / 103.6 db
722 / 103.7 db
736 / 102.9 db
750 / 103.1 db

For every 3 db difference, perceived volume to the human ear is either halved or doubled.
Example; 103.6 db @ 710 FPS is twice as loud as 100.5 db @ 498 FPS
It is clear from these results that FPS and SPL go hand in hand. To put this in perspective, I repeated the same test on my Modified Cometa Orion, which is one of the noisiest air guns I own ...... @ 930 FPS, the Spanish made rifle spits out a whopping 105.2 db of compressed air! That's almost double again the volume level of the M-Rod @ 701 FPS! Hearing protection is an absolute must in this sport1

Cheers! Avianmanor


As this been pretty much your experience, regardless of rilfle (assuming straight pipe, no baffles, silencer, moderator, muffler :P). Any given pcp velocity = somewhat linear noise increase as fps goes up? Been tinkering with mp61 converted to pcp, at 570 its not bad, 600 it starts not being backyard friendly, 675 is plain loud, havent tried more... Its the only pcp i have ever shot so i have no other reference, other then 18fpe .22 spring and 400 fps 177 ssp which is different noise... Also that mp61 eats pellets like crazy, a tin a day is easy peasy, sometimes 3, so i dont want to wear muffs.

I guess what im asking is, is there some quieter pcp at 700 that dont rely on silencer or the decibels you posted are typical of those pcp speeds.

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PostPosted: Fri Aug 30, 2019 5:45 pm 
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Location: Southern Gulf Islands, Beautiful British Columbia, Canada
Hello shoot,

Velocity and the air pressure behind the pellet are directly related to noise level -in Canada, I don't think there's any way around that as moderators are illegal in this country. I'm no expert on the subject, but it would stand to reason a longer barrel will develop higher velocity with a given amount of air pressure than a shorter one, so theoretically, air rifles with longer barrels will be a little quieter at the same velocity than those with shorter barrels, like pistols for example. Once you start getting up and over 500 FPS however, a rifle becomes less and less "backyard friendly". I would also think 'springers" might be slightly noisier than PCPs with the addition of the piston action, but not 100% certain of that.

Cheers!

Avianmanor

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PostPosted: Sat Aug 31, 2019 3:41 am 
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Joined: Thu May 07, 2015 8:30 pm
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Location: Eastern Townships
I can attest that a longer barrel WILL help reduce the report of an air gun, namely a 2240 in that particular case. I've replaced the 7'' stock barrel with an 18'' one, and with no other changes made, my pistol was definitely quieter, not ''mouse fart'' quiet, but there was a significant difference. I'm guessing it's due to the gas having more time to expand into the longer barrel. I remember also trying this on a 760 pumper, replacing the 16'' stock barrel with a 24'' one, again there was a good difference in perceived sound (no meter used).


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PostPosted: Sat Aug 31, 2019 9:03 am 
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Yep ~ I have another prove of that is recently I replaced the 14 inches barrel of my 1322 to a 8 inches one I took out from a 2240 and it became the loudest one in the house...

Sent from my S8 via Tapatalk

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PostPosted: Mon Sep 02, 2019 9:51 pm 
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Joined: Sat Aug 10, 2019 10:46 pm
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Interesting. Can you provide a more accurate info regarding the type of the sound meter and its accurate position ?
Thanks.


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