It's one of the scariest things you could experience in a war zone: a bullet strikes near you, you know not from where it came, and another one is probably on the way. Thanks to a new wireless system designed by Vanderbilt University researchers, the sound of the sniper's bullets might give away everything about them.

This fancy bit of battlefield innovation by Akos Ledeczi and his team picks up the high-frequency acoustic waves created by the blast of a high-powered sniper rifle. The system relies on four small, interconnected microphones mounted on a soldier's helmet, which pick up both the muzzle blast created by the gun's report and also the shock wave created by the bullet as it cuts through the air. They're so sensitive they can identify a sniper rifle's sound even when a AK-47 is firing at the same time.


Other systems have tracked rifle sounds before, but the Vanderbilt scientists' design, which DARPA commissioned them to make, took it to another level by going beyond just one mounted sensor. The helmet microphones talk to each other and triangulate the origin of incoming fire. They then communicate that information to a soldier's PDA, accurate to within a few meters over a 300-meter span.

Of course, field testing is one thing, and fighting it out on the streets of Baghdad is quite another. The researchers had to outfit the systems with radio chips to communicate with one another, because GPS can't necessarily track all the signals as they dart in and out of buildings.