The ROBOEAR by Brian Beard
The ROBOEAR (Robot Ear) is designed to find the direction to nearby sound sources, which in psychoacoustics, is called 'localization'. Humans can usually localize a sound to ± 10 degrees. The ROBOEAR's 8-bit PIC microcontroller and three microphone array use amplitude comparison and acoustic cross-correlation to localize sounds. The ROBOEAR can also function as an audio acquisition front-end for more powerful computers. Communication with the host computer is jumper selectable as either serial UART, or SPI.
A Complete Kit is also available: The ROBOEAR Kit