❓ Acoustics Question: Projectile Flight Noise 𐃘 How to keep it down?

[JungleShooter]

Acoustics Question: Projectile Flight Noise 𐃘 How to keep it down? ​

For a good while now, I am trying to reduce the noise that my shooting causes.

I've looked at the following:

Discharge Noise
➠ Eliminate spring guns.


Muzzle Noise
➠ Use lower power (of course, that's a given).
➠ Use a silencer, that is both long and has a large volume and small passage ways.
➠ Tune for a shorter sip of air that is at a higher regulator pressure (e.g., 8% below the max. on the power curve is better than 2%).


Impact Noise
➠ Avoid paper and cardboard targets. Instead use some type of synthetic/ plastic sheets and draw bulls on those.
➠ Soften the impact using rubber mulch or similar filler material. This is primarily for target shooting, but can also be done for shots on quarry if they often show up at the same places (e.g. a bait station).
➠ On quarry: Use slower impact velocities, smaller calibers, and projectiles that enter the flesh smoothly (pointed heads, or domes, rather than wadcutters and hollow points).



Projectile Flight Noise
That's a new one to me!
Twice now people have been telling me at private shooting ranges that they could hear the flight of the projectile wizzing by!

Here are my questions:

➊ What's quieter? Slugs or diabolo pellets?
¿Domed pellets or hollow point pellets

➋ What's quieter? Faster or slower projectiles? (below the speed of sound, that is)

➌ Is there an ideal quiet velocity — for either slugs or pellets?


For example: I wonder if the whizzing noise of my projectile would be less it I shot a .22cal pellet at 30FPE, or a .30cal pellet at 30FPE, or a .22cal slug at 40FPE?


Thanks for any input you might have! Physics was never my strong suit — I barely passed it....

Matthias

 

[markhooper]

your post this time was as good and thorough as your last long one.. very nice!! thank you .
I'll comment on what I think your title and last point said..
flight noise.. I didn't even make physics so no knowledge there and if I did do physics it must have all fell out of the other ear
first..if it's flying it's going to make noise.. yes I have heard real love bullets flying past my head when I was riding my horse and came across poachers once and took close to I suppose a marijuana grow? I don't know..
solution is simple.. no projectile flight= no noise..
another one I heard is keep you head down no I don't think you are guilty of shooting that close to anyone..
on the funny side.. shoot steel gongs.. much more fun!
I'd likely buy firebird targets, but I won't spend a dollar on paper target so not a chance for firebird targets.. I'm too poor..
yes it's always quieter if below the speed of sound.. which you stated.. and I prefer it that way although assuming that I don't know if any difference in sound between Springer and PCP.. assuming PCP is well set, of actually consider the Springer quieter even a magnum.. like a Diana 34 in 177 vs d48 in 22.. about the same but I think the d48 was quieter, definitely more accurate because when I shoot, I shoot..wind or not..
I think the d48 in 177 would be definitely louder than 22 unless you use jsb beasts to keep it subsonic..
I'll write more later and follow this thread..
t
I just remembered the last one I read you wrote.. what is the best airgun for my application..
myself I hope it's the one that is showing up Monday..
if not is it ok to PM you, I have very specifics, know what I want and don't want.. but might be guns I'm overlooking that are the one..
thank you for writing such great post
Mark

 

[UDABEGGER]

Stay below the speed of sound !

 

[greenbeans]

I think in the end it’s fairly simple. The faster they go to louder they’ll be. I once had my u2 shooting slugs at 1080fps. The loudest part of a shot was the slug passing maybe 1-2 yards past my wood stacks (target box behind the wood stacks). Once I had them down to 1030 the crack from passing the wood stacks went away. The projectile traveling will push a wave of air which translates to sound. The more pressure behind that wave (faster projectile), the louder it’ll be. For domed vs slugs vs HP, I don’t think it makes much of a difference to the human ear to be honest. It’s a pebble of lead pushing through the air… but then, you learn something new every day I guess so open to others with more knowledge chiming in!