Anti Sound for an outdoor shooting range

Hi, i don't know much about anti sound but i would like to build system to use anti sound to cancel out the crack of the bullet moving through the air. and my second question is how much would it be to build such a system? If you guys can help me out great if not thanks anyway!


-Steinmaster
 
There are two sources of sound from the discharge of a firearm. One is the "bang" created by the burning powder as it pushes the bullet out of the barrel. The other is the mini sonic boom (the "crack" that you hear) created by the bullet moving faster than the speed of sound.

It is possible to create a sound that is equal, but of opposite polarity that can theoretically cancel an unwanted sound. The "anti sound" source would have to be very close to the sound source. There was an "anti sound" automobile muffler patented, and prototypes made, a dozen or so years or so, but it's lifespan wasn't too good. The transducer was inside the muffler.

This technique could be used to cancel the "bang". Legal issues notwithstanding so can a suppressor (silencer). Both options would require a separate device for each firearm, and the "anti sound" technique (if even possible) would require different "anti sounds" for each type of ammo in a given gun.

The "crack" is a different issue. How do you use sound to cancel a sound source that is moving faster than the speed of sound? The bullet will outrun your "anti sound." I believe that this issue is not solvable in this manner, or certainly not cost effective if it is possible.

Subsonic ammo is a possibility in some guns. I have fired a .22 pistol with subsonic ammo and a suppressor (class 3 permitted), and all I could hear was the action clicking as the old round was ejected and the fresh one loaded.
 

eriksquires

Member
2013-05-10 4:11 pm
This is probably way off topic. The best, closest I've seen to this is research into creating barriers for tsunami's.

Imagine a row of rectangular posts. As planar waves travel through the line it has to go through multiple spaces made up of the distance between each post. The single coherent planar wave is broken up into smaller parts and on exiting the small channels has to re-radiate spherically. This causes much of the energy to now travel at an angle from it's original vector. In effect this turns the planar wave into multiple point sources. This is the same as when a line source uses many drivers whose diameters are far smaller than the wavelength of the frequency they are radiating and/or spaced too far apart.

By adding multiple rows of these posts it's possible to dissipate an acoustic wave more and more. Each row causes the remaining energy to be re-radiated, becoming less coherent and more directed at an angle to the original vector.

Sadly, there's no good way I know of to put up such a barrier and still leave the source visible.

Best,


Erik
 
Last edited:

Ron E

Member
2002-06-27 10:41 pm
USA, MN

eriksquires

Member
2013-05-10 4:11 pm
So I guess what Erik is saying is that you need to EnABL your gun by painting little dots on it. This will not only make it quieter, but it will improve your aim, and make your bullets faster and cause less harm to the environment.
http://www.diyaudio.com/forums/multi-way/100399-enabl-processes.html

Hahaha, no such thing, but I wonder how much of this is similar? In the case of the tsunami barrier, it's not about painting rocks, it's about sticking 30' tall rectangular pylons in the water. :)

I was certainly not thinking of EnABL at all. What I meant to discussing is much closer to traditional bass traps, but now I'll have to consider if and where there are similarities.

Best,


Erik
 

FrankWW

Member
2004-07-29 7:59 am
n/a
phononic crystals

https://www.google.com/search?hl=en..._occt=any&safe=images&as_filetype=&as_rights=

This is probably way off topic. The best, closest I've seen to this is research into creating barriers for tsunami's.

Imagine a row of rectangular posts. As planar waves travel through the line it has to go through multiple spaces made up of the distance between each post. The single coherent planar wave is broken up into smaller parts and on exiting the small channels has to re-radiate spherically. This causes much of the energy to now travel at an angle from it's original vector. In effect this turns the planar wave into multiple point sources. This is the same as when a line source uses many drivers whose diameters are far smaller than the wavelength of the frequency they are radiating and/or spaced too far apart.

By adding multiple rows of these posts it's possible to dissipate an acoustic wave more and more. Each row causes the remaining energy to be re-radiated, becoming less coherent and more directed at an angle to the original vector.

Sadly, there's no good way I know of to put up such a barrier and still leave the source visible.

Best,


Erik