Theory

3 microphones, on a disc, 120 degrees apart. You measure precisely the small time difference between when the sound reaches the microphones, this gives you a direction.

Doc and links

• The theory
  • Sound localization http://en.wikipedia.org/wiki/Sound_localization
  • Multilateration http://en.wikipedia.org/wiki/Multilateration
  • Sound localization for artillery http://en.wikipedia.org/wiki/Sound_ranging
• One successful (?) sample with arduino http://filear.com/?p=11
• One student project pretty successful it seems http://people.ece.cornell.edu/land/courses/ece4760/FinalProjects/f2013/agw39_mag338/agw39_mag338/agw39_mag338/agw39_mag338.html
• http://hacknmod.com/hack/diy-sound-localization-sensor-with-arduino/
• http://www.school-for-champions.com/senses/heardirection.htm
• http://hackaday.com/2011/05/10/diy-sound-localization-sensor/