It's not that loud in my case, but enough to affect my neighbourhood.
When the pressure goes up, the sound is more "sharp" and can be more identified as a gun, in my opinion. I just make a silencer to be quieter.

Thx for your advice, but I don't think I have all the hi-tech tool and accuracy for a wave cancelling system, and according to wikipedia it's not proven that it could work...

Hello, I am coming from a french forum ( http://patator.frbb.net ) and I have a question which you could answer better.
I am making a silencer for my 8mm pneumatic canon (I put from 100 to 450 psi of air in it) :

http://i68.servimg.com/u/f68/14/28/37/35/silenc10.jpg


I have ceramic wool to ...