Gunshot - Gunfire Characteristics

Gunfire Characteristics

There are three primary attributes that characterize gunfire and hence enable the detection and location of gunfire and similar weapon discharges:

1. An optical flash that occurs when an explosive charge is ignited to propel a projectile from the chamber of the weapon
2. A muzzle blast that occurs when an explosive charge is ignited to propel a projectile from the chamber of the weapon. A typical muzzle blast generates an impulse sound wave with a sound pressure level (SPL) that ranges from 160 dB to 180 dB
3. A “snap” or “crack” caused by the sonic boom that occurs as a projectile moves through the air at supersonic speeds

Gunfire can be confused with other sounds that can sound similar, such as firework explosions and cars backfiring.

Urban areas typically exhibit diurnal noise patterns where background noise is higher during the daytime and lower at night, where the noise floor directly correlated to urban activity (e.g., automobile traffic, airplane traffic, construction, and so on). During the day, when the noise floor is higher, a typical handgun muzzle blast may propagate as much as a mile. During the night, when the noise floor is lower, a typical handgun muzzle blast may propagate as much as 2 miles.

An attachment commonly misnamed a silencer can be attached to the muzzle of a firearm to decreast the audio signature of firing the weapon. The sound of firing is only decreased and is still considerable. The FBI estimates that 1% or fewer of crimes that involve gunfire are committed with silenced gunfire.