Hi, Martin, I missed the first post on this, but I have heard a master tape made of the monks that produce sub harmonics. The recording technician had a lot of trouble getting a clean recording because the ringing of little bells was so much louder than the monks voices; it caused overload and distortion. The monk _inhaled_ to produce the sound so much lower than anyone can normally sing. Double piping on organs to produce a fake lower tone is and has been a common practice for centuries. Newton
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