This article was written by me and originally appeared in Safezone Magazine.

A question I often see on the forums is "How loud is an airsoft pistol?".

A flip side to that is "Which is the quietest airsoft pistol", so I thought I'd try and measure it.

I bought a basic sound meter from eBay. It is analogue (wavy arm, to you and me!) and doesn't have the ability to record maximum levels, so there is degree of inaccuracy in my tests caused by

a) the arm moving continuously
and
b) me having to judge where the needle reaches as a peak.

simple analogue sound meter

Fortunately, the purpose here is to assess the comparative loudness of different pistols and the overall level of sound compared to everything else.

Now, if you're like me, you probably didn't have a clue what a Decibel was until you started reading this, so I tracked down a rather handy little table (Source: National Institute of Deafness and Other Communication Disorders), which lists common sources of sound and how loud they are.

SoundNoise
Level
(dB)
Effect
Jet engine (near) 140
Firecracker 140
Gun firing 140
Rock concert 110-140
Boom box 120 Threshold of pain (125 db).
Thunderclap (near) 120
Stereo (over 100 watts) 110-125
Chainsaw 110
Jackhammer 110
Snowmobile 105
Airplane (near) 103
Garbage truck 100 Regular exposure of more than 1 minute risks permanent hearing loss (above 100 db).
Farm tractor 98
Motorcycle (near) 90 No more than 15 minutes of unprotected exposure recommended.
Subway 88
Lawnmower 85-90 Level at which hearing damage begins (85 db).
Television 70-90
City traffic noise 80 Level at which constant exposure may cause hearing damage.
Alarm Clock 80
Washing machine 78
Dishwasher 75 Long exposure to sounds less than 75 db is unlikely to harm ears
Vacuum cleaner 70
Hair dryer 70
Laughter 60-65
Normal conversation 50-65
Refrigerator humming 40
Quiet room 40
Whisper 30
Rustling leaves 20

Decibels are measured on a logarithmic scale, so a rise of 10 dB in sound level corresponds approximately to a doubling of subjective loudness. That is, a sound of 85 dB is twice as loud as a sound of 75 dB which is twice as loud as a sound of 65 dB and so on. That is, the sound of 85 dB is 400% times the loudness of a sound of 65 dB.

If you are really interested, there is lots more information at : http://www.rtagroup.com.au/wizard/definition_acoustics.html and http://www.e-2-s.com/kb-3.htm.

I used the calibration button to set my meter and then monitored a quiet room - Sure enough, it comes in around 40dB.

So, knowing the meter was reasonably accurate, I devised a way of testing airsoft pistols.

Setup for test

I decided to fire 5 bbs from each gun into a soft material (to eliminate the sound of the BBs hitting) and to measure the sound of each gun a set distance (10 CM/4 inches) away from the muzzle (to try and give a balance between GBBs, where the slide causes a lot of noise, and NBBs).
As I fired each BB, I observed the highest point that the needle reaches and averaged my observations out over the 5 shots. I found that I was able to be accurate in determining the peak dB to within one gradient on the gauge, which is 2 dB.

So, onto the results...

First gun tested was a springer, my TM S&W PC356.

The sound is very sharp and plasticky and most seems to come from the spring releasing in the frame. The average was 84dB.

Next up was a NBB, my Maruzen S&W 4506. This has a very abrupt, 'pup' sound to it and recorded 88dB.

Finally, I tested a GBB, my KSC MK23 SOCOM. This is an especially interesting gun as I have a foam filled silencer for it (the TM one from the NBB Mk23) and I was interested in the actual level of sound suppression that accounted for. The sound is best described as a hollow 'pop', but a lot of metallic sound is mixed in.

Most of the sound of a GBB emanates from the slide moving and it was no surprise that it was the noisiest at 94dB.

What I did find impressive (and giving lie to the belief that the sound is all in slide, perhaps) was that this dropped to a mere 86dB with the silencer fitted (a drop of almost 50%). Imagine that on the already quiet TM NBB Mk23 and you have an idea why it is widely acclaimed as one of the quietest airsoft guns around.

Subsequently, I tested another 6 guns and recorded almost identical results for each type of gun (NBB or GBB). This would suggest that all guns of a particular type are pretty much even on volume, although different guns have a different tone to their sound, which makes some seem louder than others.

Springer - TM S&W PC356 84dB
NBB - Maruzen S&W M4506 88dB
NBB - Marushin Bren Ten 8mm 86dB
NBB - Tanaka S&W M29 6.5" 84dB
GBB - KSC H&K Mk23 SOCOM 94dB (86dB with silencer)
GBB - Western Arms SV Infinity Ltd 6" 96dB
GBB - Western Arms Beretta Cougar 8045 96dB
GBB - KSC S&W Performance Center M945 94dB
GBB - KSC M93R II 94dB

I will apply the sound test to all my guns in future to give an idea of the relative 'noisiness' of each gun.


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