Impact Transient
Definition
The acoustic energy released when the projectile strikes a surface. Its character depends on the target material (wood, concrete, soft tissue) and can indicate the bullet's final destination.
- Signal type
- Short acoustic burst on impact
- Influencing factor
- Target material
- Forensic use
- Indicates projectile's final destination
- Distinguishes from
- Muzzle blast, shockwave
Common questions
How is an impact transient distinguished from the muzzle blast in a recording?+
The muzzle blast occurs at the moment of firing and radiates from the shooter's position, while the impact transient arrives later, delayed by the bullet's flight time, and its acoustic signature reflects the struck material rather than the weapon.
Can an impact transient confirm what the bullet actually struck?+
It can suggest a general category, such as a hard versus soft surface, from the transient's spectral character, but confirming the specific material usually still requires physical recovery of the projectile or the struck object.
Related terms
- Ballistic Shockwave
- An N-shaped pressure wave produced when a supersonic projectile displaces air faster than the air can move out of the way. It...
- Confounder
- A non-gunshot acoustic event that shares characteristics with a firearm discharge: vehicle backfire, fireworks, industrial tools, and tyre bursts are the most...
- Muzzle Blast
- A broadband impulsive pressure wave generated when high-pressure propellant gases exit the barrel behind the projectile. It radiates roughly omnidirectionally and is...
- ShotSpotter
- A commercial urban acoustic gunshot detection and localisation network that processes impulsive events from distributed microphone arrays to estimate shooter location and...
- TDOA (Time Difference of Arrival)
- The difference in arrival time of a sound at two spatially separated receivers. Each measured TDOA constrains the sound source to lie...