Sound meter app?

[Raydee38]

I got a couple moderators in the mail today and wanted to see how much they quiet my rifle down. I downloaded an app and wonder if there is a standard distance the mic should be placed from the muzzle for the test? There is a setting for frequency weights, A, C and Z, anyone know which should be used for an air rifle?

 

[Hold_Over]

I use Decibal-x. I am mostly concern with a change in the reading before and after a moderator etc. So as long as my before and after tests are the same distance away so I can tell it's dropped 8db etc I don't care too much if it's actually 89 or 90 db as long i can get a read8ng that illustrates the change.

 

[Firewalker]

I have a really good sound meter, a cheap sound meter and my cell phone. The three all agree on the sound pressure outside at 30 feet but only the really good meter is consistent indoors or at the ear.

Frankly, they all are close enough to the same measurement to not matter for the casual user.

Powder burners use a standardized testing format but here's one that is novel:

Many unsuppressed and suppressed firearms, in various calibers and with various silencers, were fired 1.6 m above the ground. Sound pressure was measured at the following locations:

1. Muzzle (1.0 m left of the muzzle, at 1.6 m muzzle-and-microphone elevation) - This is the “MIL-STD” muzzle location.
2. Ear (0.15 m right of the right ear, 1.6 m ear-and-microphone elevation) - This is the “MIL-STD” ear location. This was done with the shooter present; that is, the firearm was fired by a human with the human’s head 0.15 m from the microphone.
3. “Far Field” and “Non-Standard Muzzle” (2.0 m or 1.0 m right of the muzzle, at 1.6 m muzzle-and-microphone elevation) - These are “control” locations and this data is not currently published.

 

[Raydee38]

My iPhone seems to be picking up good. I saw a max measurement of 117db but I also saw a much higher C weighted reading that I find very hard to believe, that is why I asked what weight I should be using.