🚀 go-pugleaf

In article <1992Nov19.170622.13991@mailer.cc.fsu.edu>, meyers@lorenz.ocean.fsu.edu (Steve Meyers) writes:
|> 
|> The name of the company is Andrea Electronic Corp. Anyone 
|> have an opinion on their new claims.
|> 
|> Steve

I have heard nothing about them.  However, I was wondering if
they are using active noise cancelling technology (?).  Some years
ago I saw a report (from England, I believe) about a noise
cancelling system used industrially on a gas turbine generator
exhaust stack.  A ring of drivers mounted around the stack were
driven with the phase-reversed noise signal and achieved a significant
reduction in the net noise strength.  They took an impressive amount
of wattage to run, but the power consumed was a small fraction of
the generator output.

A similar approach could be used in the vicinity of any noisy
machinery.  The acoustics would probably get difficult in diverse factory
environments, however.

Active noise reduction (ANR) is in use in a number of aviation
headsets.  The first commercial product was offered by Bose a
few years ago and there are now at least three other makers
offering them.  The passive attenuation properties of the headsets
reduce the higher frequency noise significantly (21dB is typical).
The ANR is used to reduce the mid to lower frequency noise.  Their
effectiveness is highly praised by pilots (who can afford them...).

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Michael Corvin 	      				zwork@starfighter.den.mmc.com
GN&C research & development 		   Martin Marietta Astronautics Group
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===============    My views, not Martin Marietta's   ========================
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