According to the Deseret News, a physics professor who studies sound at BYU is working on building an indoor shooting range for Hill Air Force Base in Utah.  Kent Gee has studied sound for NASA, as well as other agencies, so he is used to overpowering sound.  The Air Force wants to shoot their Warthog gatling guns without disturbing the neighborhood,  and so far it seems that the concrete walls are being destroyed  by the sound, not to mention the cannon's projectiles.  You need double ear protection just to shoot .44 magnums inside, this range must be a hoot!  I would also like to see what they use for a bullet trap.

Pic of Warthog Gatling Gun