Beam-forming microphones are well known. Here's a fancy ceiling-mounted one for video conferencing.[1] Here's the theory in Matlab.[2] And, most impressive is the surveillance version, the Squarehead Audioscope Acoustic Camera.[3] This, a 1m disk with 384 microphones, can pick out a single conversation in a noisy arena.

There's a version which records all the audio channels in real time, using a big disk array. This allows the phased-array processing to be done during playback, so the "aiming" can take place later. The company now has its catalog of surveillance products password-protected, but in the past, there's been more info about that application. The DEA has purchased two.

There are also "acoustic cameras" for locating noise sources.[4]

All this is a spinoff of submarine passive sonar technology from decades ago.

[1] https://www.youtube.com/watch?v=Bepqav87D40 [2] http://www.mathworks.com/help/phased/examples/acoustic-beamf... [3] https://www.youtube.com/watch?v=bgz7Cx-qSFw [4] http://www.acoustic-camera.com/