From: Dereverberation and denoising based on generalized spectral subtraction by multi-channel LMS algorithm using a small-scale microphone array
Linear array
Circle array
2 channels
17, 29
1, 9
4 channels
17, 21, 25, 29
1, 5, 9, 13
8 channels
17, 19, 21, 23,
1, 3, 5, 7, 9,
25, 27, 29, 30
11, 13, 15, 17