The PeanutBot robot consists of three microphone circuits, three servo motors, an MCU and a PC. The three microphones were used to triangulate the angle of the source relative to the robot. The audio source plays a continuous stream of pulses. Pulses were chosen over a continuous tone because, instead of detecting phase difference in the audio signal, our system detects the arrival time of the signal at a certain amplitude at each microphone.
Autonomous Sound Finding Robot - [Link]