Regarding Matthew's interest in a contact microphone to isolate the
readings for a single pipe when more than one pipe is playing, the
problem could arise that frequency produced by a pipe may well be
altered by another pipe that is playing at the same time.

This is more true if the pipe is of a broad scale, and less likely if
one pipe is of narrow scale.  The "draw" that occurs with two pipes of
wide scale can be enough that it will cause mis-tuning.  A contact
microphone may not work very well in all circumstances.

Bill Chapman,
AMICA Membership Secretary
in cool B.C., Canada