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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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Air Arms S510 Extra
FX Streamline
Daystate Huntsman Classic
Hatsan BT65 SB
Benjamin Marauder
Cometa Orion
Weihrauch HW100S
QB78D Modified HPA 875 FPS
Brocock Concept Super 6
Artemis PP700S-A
Diana Chaser Camo
Snowpeak CP1-M
Artemis PP800


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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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Location: Kingston, ON
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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