> my old idea of mounting 4 mics in a tetrahedral (pyramid shape)
Kevin,
Such a system was invented and patented by Michael Gerzon and Peter Craven
back in the early 1970s, and the microphone is now known as the Soundfield
microphone:
http://www.soundfieldusa.com/
The patent is no longer in force.
It was demonstrated by Gerzon that a tetrahedral array of loudspeakers is
NOT the best way to reproduce the signals. Although the microphone capture=
s
information that includes height information, the height information is
almost never reproduced (unfortunately). For practical reasons almost all
reproduction systems involve a horizontal circle of loudspeakers, say 6 or
8, or even more.
I have used a Soundfield microphone, either the commercial one or one
assembled out of individual microphones, to make numerous nature recordings
and I find it very satisfactory for my purposes. But it is not without
flaws. A great deal more information can be found at:
http://www.ambisonic.net/
and in the more than 100 technical papers on the subject published in the
Journal of the Audio Engineering Society, and elsewhere.
Eric Benjamin
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