Hi,
you ask us doing your homework...
without giving any value.
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* first you have to decide what is your mechanical construction (relative position of the microphones in 3D)
* then you have to decide what angular range you want to detect
* Then you have to decide what angular resolution you need
* Then you need to know about sample rate
* is there a known signal or an unknown waveform sent out
with all these informations/decisions you can calculate if a simple timing analysis (timing of zercross in signals, for example) or a more precise mathematical solution (cerrelation for example) is needed.
The human system uses both "level" for low frequencies and "delay" for high frequencies.
Klaus