The GAU-8/A Avenger Gatling Gun is the primary weapon system on the A-10 Warthog and produces a very distinctive sound upon firing.
A recent test firing of the Avenger while it was secured to a tripod provides the clearest profile of the machine gun's song. Most people refer to this unique auditory signature as a "brttttttttt" but some have even compared it to the sound made by the tripods in War of the Worlds.
The special noise produced by the gun is a result of its extremely high rate of fire. In the test video, 170 rounds are fired in the two-second burst, according to The Aviationist. The Avenger can fire at such a high rate of speed due to its seven-barrel configuration. The multiple barrel design, a direct descendant of the original 19th century Gatling gun, allows each barrel to cool between each shot and prevents the gun from overheating. That means the Avenger can achieve a fire rate of more than 3,900 rounds per minute.
The "brttttttttt" is said to be one of the most reassuring sounds an American infantryman can hear as it signifies that a world of hurt is coming down on his enemies. Or, as Wired‘s Jordan Golson put it in a recent defense of the aircraft, the A-10 "is ruthlessly effective, and the grunts on the ground absolutely love it because it keeps them safe. If you need to hit a nail, a hammer is exactly what you want."