Frank van der Hulst wrote:

(Another thought -- what about some kind of ANR on/in the exhaust pipe?
A heat-proof microphone connected via an ANR circuit and amplifier to a
heatproof speaker placed close to the exhaust. Or would this take an
exhorbitant amount of electricity to drive? How much energy is in the
exhaust sound anyway? Oops... we're back to needing absolute amplitude!)

  Ive done some work with cancellers (RF, not audio). It could be done but
the power required would be significant if you are trying to cancel the
sound at the source. You cant get something for nothing. :-)    I remember
reading about GM and Lotus experimenting with this a number of years ago. I
think if it were viable you would see it on production cars.

  On the other hand, cancellation at the victim ( in this case the pilot
and co-pilot) is very do-able. Thats why I asked Finn if he uses ANR
headsets. An ANR headset that was designed specifically for this
application could work very well. Of course that does nothing for the rest
of the world which would still have to listen to you.

Mike Wills

 
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