Cameras often do record sound. There's also systems like ShotSpotter - http://www.shotspotter.com/ http://www.shotspotter.com/ - which are essentially recordin

Cameras often do record sound. There's also systems like ShotSpotter - http://www.shotspotter.com/ http://www.shotspotter.com/ - which are essentially recording, in high fidelity from numerous points within a city, the sound of everything that occurs. Acccording to this NYT piece the system can pick up“doors slamming, birds chirping, cars on the highway, horns honking” as well as conversations. http://www.nytimes.com/2012/05/29/us/shots-heard-pinpointed-and-argued-over.html?pagewanted=all http://www.nytimes.com/2012/05/29/us/shots-heard-pinpointed-...