Multi-directional microphone

Security systems often involve cameras, each generating a large bandwidth of signal which may be recorded for hours or days on a loop.

Audio, on the other hand, is seldom captured - why? Well, for one thing a microphone covering a large area will not pick up voices from some distance away, over any background noise. Highly directional microphones are available, but of course they only cover a narrow window.

So, why not have a roughly-spherical (or part-sphere, depending on needs) device, about the size of a football, consisting of a dense array of highly directional microphones, radiating outwards in all directions? The sound from each is recorded, collectively taking up (I would guess) not much more bandwidth than the output of a single camera. In the event of a crime taking place, the sound recorded from the various channels can be played back, until the right channel (right direction) is found. Or, if a camera is mounted nearby, the image would tell you which sound channels are likely to have captured voices.

Sound is, of course, not nearly as useful as video in bringing prosecutions, but it can still be a valuable adjunct to video. With a little audio processing, you would even be able to infer the direction from which sounds have come, even if they were produced outside the camera's field of view.