How Can Multiple Microphones Locate a Distant Sound Source?

[apepi]

Not sure which section to post this in, but here goes. It's entirely my own words - might look like homework but it's for electronics.
Multiple microphones are connected to a computer. A sudden sound, like a gunshot, goes off in the distance. These microphones are separated from each other by a known distance, and the time of arrival of the gunshot sound is known for all microphones.
The computer also knows the speed of sound, but it does not know the exact time the noise was made, nor the original frequency, ruling out Doppler Effect calculations.
Any suggestions for an algorithm or minimum amount of microphones? I've been looking for methods, like sound ranging etc, but I've come to naught.
Thanks for any help

 

[Simon Bridge]

I think it's three microphones - not co-linear.
IIRC: two will give you a line of possible locations. The third will give you three lines. They should intersect.

If the gunshot was at point G, and you have two microphones at P and Q, then a shot heard at t_P and t_Q at each detector started out on a line so that the path difference is c|t_P-t_Q|.

 

[apepi]

Multilateration it is, then. Thanks for the help