need help to build a follow me sound detector robot

[robot-achu]

hey ppl , im a 1st timer wit respect to robotics ,im a final year engineering student n this robot has been assigned to me for my final year project.  i need to construct a sound source detector robot in 3 months time.
the specifications which i hav figured out is to use a 4 microphone array , i was able to amplify the mics range to 4 mts using 2 amplifiers per mic.
i seriously need some help wit respect to dsp on time delays( to identify the source coordinates)
suggestions pls .............