dB Distance MAP

[PCArms]

Robert, (or others)

Is there a formula or MAP, to figure dB loss in feet from subject?
(sorry, I loaned my Suppressor I & II books to a customer)

What I was looking for is, say, 3', 6', 12', 24' circle around the DUT,
(I mean Subject/Firearm)
or a 3dB drop every "x-feet"

Thanks,

[mpallett]

I think it is something like 6 dB per meter - it is burried somewhere in one of rsilvers posts about calculating the SPL from an M4 at 2 meters instead of 1 meter.

[silencertalk]

If you double the distance it will be 6dB less sound.

This is of course not exact because of humidity and pressure, but very close.

[Racer]

I believe that a formula that will provide the db at any distance would be:

S(at distance r) = -20 log r + db@1 Meter.

So if suppressed sound at 1 meter is 120 db, and you are interested in the sound at say 32 meters: S=-20log(32)+120 = 90 db.

Using the 6 db per double of distance will yield essentially the same result:

Distance/ db
1m/120db
2m/114db
4m/108db
8m/102db
16m/96db
32m/90db

The nice thing about the formula is that you can calculate the sound at any distance without making a table of distances.

BTW -- PCArms -- nice to see all your goodies at Albany. I was shooting at the other end of the line.

[PCArms]

That is exactly what I was looking for!

Thanks!