It was recorded on a Zoom H2 (four mics.) The Zoom H4 is only two
mics. There's a new one.
I recorded it in full quad, so two tracks, front and back, both stereo.
I then used Audacity to invert the back channel, so the waveform is
flipped upside down (i.e. not invert left and right, but actually flip
the signal upside down) which is a one click operation in Audacity and
most other editors.
I then burned it down to two channels and saved it.
It works because far-off sounds are heard at nearly exactly the same
volume at all four microphones, so when you flip the signal and add,
it cancels fairly effectively. The voices near the mics are a bit
louder on one side than the other side, because the distance between
the mics actually makes a difference in volume at 30cm, so when you do
the invert-and-add you're left with a signal.
I read the trick online. The audio is here!
http://files.howtolivewiki.com/FSFI/global%20swadeshi%20FSFI%20hresso%20final.m4a.mp4
