Air Rifle Sound Testing

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17bullet

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Apr 1, 2015
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Seems as if the question of how different airguns sound can go on forever without a clear answer.

If one person like Ted would set up a testing procedure that used one lap top set at the same distance from the air rifle at all times. And had access to many different air rifles the sound question might have more reliable answers. It would also be nice to have a reference noise just to use as a standard.

The computer program to use is Audacity, It is a free download from them. I use a real sound meter for testing but to really hear the difference Audacity is great because you can stack the shots one after another and play it as much as you want for comparison. The sound wave can be looked at and inspected to also see the hammer noise that will show if you air rifle is really quiet, being shown at the front of the wave. All cell phone apps are just meaningless, as they are not a reliable source of accurate information.
Maybe someone might give it a try it is a great program.

http://audacityteam.org/ 
 
if there is anyone in the Northern Virginia area, DC, or MD with a WildCat .25 or .22 I am willing to pick up a REAL DB meter to get real world results and we can put the whole thing on video. That will solve the question on that in a hurry. I am not affiliated with anyone and am just an individual who loves science and facts. 
 
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This is what the program Audacity can show.

This is a screen print from the program showing 3 shots being fired.
The sound waves read from left to right. They can be played again and again to hear the difference, when using the program.
The sound wave on the far right shows a stock FX 22cal. Independence, which is felt by some to be fairly quiet..
Middle same rifle that has been improved some; hammer noise can just be seen at start of wave.
Left same rifle but has been improved more; as can be clearly seen the hammer noise and report of rifle is nearly the same
.Being able to see and hear the difference is clearly a great advantage in assuring proper success.

 
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"17bullet"... All cell phone apps are just meaningless, as they are not a reliable source of accurate information.
Maybe someone might give it a try it is a great program.

http://audacityteam.org/ 
Click to expand...
Here is a referenced study that indicates that at least some cell phone apps measure within 2db of a reference sound meter on some sounds.
Following link and a quotation are from another thread on this forum discussing sound comparisons where the discussion of methodology lead to an argument.

http://airgunnation.dev/topic/looking-to-buy-a-bullpup-but-which-one/page/4/#post-16720

[quotation] Here are a couple articles about db apps compared to a real meter ( scientific ). http://scitation.aip.org/content/asa/journal/jasa/135/4/10.1121/1.4865269
http://blogs.cdc.gov/niosh-science-blog/2014/04/09/sound-apps/

If I understood what I read, It looks like choice comes down to two apps, SoundMeter and SPLnFFT with the first being Android and the second being for iPhones. I plan to buy the second. I will see if I can use Audacity to give us a visual for comparison.
 
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Audacity is good. Sound meters are good. I've used both when sound recording was my hobby. But I found that perceived sound (which we want to compare for different guns, calibers and energies) is a very different animal to measured sound. A measured sound test won't settle any arguments, I promise you.

To be frank, I think a blind* listening panel, giving subjective ratings out of 10 for many different rifle/LDC/ calibre/energy configurations shot at 90 degrees from them, 20 yards away, behind a sheet screen would give more useful information.

*By blind, I obviously mean unaware of which gun/LDC/ calibre/energy configuration is being tested. Though actually blind testers would be better qualified to judge.

Edit: By the way, Audacity is very good for measuring Ballistic Coefficients.
 
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… All cell phone apps are just meaningless, as they are not a reliable source of accurate information.

The reason I believe this is still true is there is no calibration standard. You are just getting a number. Knowing that a 10 decibels change is twice the perceived sound change using anything less than a true sound meter and stating my gun shows ??decibels is a hoax.

I use a Extech model 407736 sound meter for readings. I also use C weighted scale as it is recommend by the company for more reliable readings of this nature. Has built in calibration standard and max hold readings. But even still this meter is not reliable as being accurate for gun fire, so I do not state decibel readings for that reason.


To be frank, I think a blind* listening panel………………

While on the surface this sounds like a great idea. But how would you ever expect a panel of different people to remember the many different shots being fired? Let’s see I think shot 8 was quieter then shot 3 please shoot 8 and 3 again. Another person says 11 and 5 and then you are up to number 15. And this if you do it all in one day. You would be relying on the memory process which would be a disaster.

The reason I use Audacity is still clear. If the set up is repeated accurately then it is possible to record and see differences and inspect the actual sound wave for changes.

I will certainly agree that air guns can make different types of sounds and one might find one more quiet then another. The surroundings would also have a great influence as well as what noise is present at that time. I was just trying to add another possible way of determining the sound of different airguns.
 
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