sub-audio pickups (not wholly OT)

[Paul Perry]

http://www.seismicnet.com/info/psnl96q3.txt

is a ref to work on detecting/measuring sub audio
sounds in the atmosphere. (I guess where I live it would
mostly pick up car doors slamming).

Over on AH people were asking, what kind of sound is there
below 20Hz? this is the sort of gear you would use.
As for actually HEARING it, if you took a sub-audio 
signal and ran it into a DC-coupled ring modulator, you could
modulate it with an audible tone & get an output that 
increased adn decreased as the absolute value of the sub-audio
waveform waxed and waned.

Or, what I would rather do, is modulate a VCO with it.
Much more fun & easier to hear.

paul perry (Frostwave analgo fx) Melbourne Australia