Gunshot

The sounds may be heard at greater distances in the direction of bullet travel than behind or beside the gun.

A firearm's muzzle blast may be masked by ambient noise during the daytime, but may be detected at greater distances during the quieter hours of darkness.

A popular urban gunfire locator system typically uses six to ten audio sensors per square mile for trilateration.

Suppressors attached to the muzzle will not reduce the sound of high velocity gases released from other locations, such as the gap between the cylinder and barrel of a revolver.

A muzzle suppressor is similarly ineffective in reducing the snap of a supersonic bullet or the noise produced by the mechanical action of a self-loading firearm.