With two or more microphones the direction of the sound can be calculated if we know the distance and the time delay between the microphones.
Let's look at the example setup (Image 1). The angle alpha can be calculated if we know the distance D between the microphones and the distance A. To calculate the distance A we need to know the speed of sound in air and the time delay between MIC 1 and MIC2.
When the distance from the sound source is much larger than the distance between the microphones the angle can be estimated as:
The excel file angle.xlsx can be used to calculate the angle when we know the parameters - D, R and delta R.
Ivan Tashev: Sound Capture and Processing: Practical Approaches
TDE source code