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Just a quick note about this subject on ANR
Headsets.  Earl Schroeder is correct.  Most people
think that ANR is supposed to cancel 15-25db of
noise.  To simplify things, ANR is a process in
which a band of frequency (1K hz down) is
"re-played" back into the earpiece 180 degrees out
of phase.  ANR headsets work well at reducing
cockpit noise if the unwanted noise is in that
frequency range.  If you want to demonstrate to
yourself the effect ANR has in a headset, reverse
the speaker wires (at the speaker) on one of your
home stereo speakers.  This will cause one speaker
to "push" the speaker driver out while the
reversed one will "pull" the driver in.  The
effect is a cancellation of bass and mid-bass
frequencies.  I personally fly with an ANR headset
and absolutely love it (Flightcom Denali) but it
boils down to the application you are using them
in.  Hope this helps.

Kirk Hammersmith

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