From:	Joe McNulty <mcnultyj@****.JMB.COM>
Subject:	Headsets
Date:	Fri, 1 Oct 1993 09:22:26 CDT

> waves interact, they wind up canceling each other out. The tech exists, but I
> really don't know why no one's done research this century on it (or have they?
> I may have missed it) And they have been used. In headsets, to cancel out the
> loud exterior noise. In helicopters, and I believe Dick (Ruttan) used one in
> his flight. Hope this helps...]<<<<<
> -- Brodie (15:30:05/09-29-54)

As far as helicopter and airplane headsets, their noise cancelation works like
this. You have two Large earphones on your ears that muffle almost all the
sound. The mike has receivers on two sides, one on the same side as your mouth
and the other opposite. The "noise cancelation" works like this. Cockpit noise
goes into both sides of the mike, and cancel each other out. Your voice comes
in one side much more strongly than the other, and the mike x-mits to your
headset/intercom/radio, depending what you are doing.
No real high tech there. Of course, noise cancelling headsets sure sounds like
it if you haven't used 'em, just like semi-automatic assault rifles bring
visions of autofire to those not familiar with guns. <Not that out local news
showed a demo of an M-16 firing in full auto when chicago was passing an
ordanance to ban all SEMI-automatic assault rifles, so of course the public
cheered...>

Later,
joe