you can tell a lot from a waveform. how loud, how high, what frequency. train a computer algorithm and it can, in theory, work out what it might be listening to. the's the idea behind shotspotter — that a computer can detect a gunshot and then tell the police the location it was fired from. gun fire. small mics are placed around a neighbourhood. when a gunshot is fired the mics pick up the sound, how long it took to reach the sensors and from which direction, effectively triangulating the shot. shotspotter was founded on the west coast of america in the mid—90s, in that cradle of american innovation, silicon valley.