mono/mono — pull request #525 by Arakis (2012-12-21 10:58:45+00:00)
Title: Update mcs/class/System/System.Media/AudioData.cs

Since this line is commented out:
int block_align = buffer [idx++] | (buffer [idx++] << 8);
you will ran into a "bits per sample" exception.
Adding the two increpements (idx+=2) will solve it.