"Jerry G." wrote in message
...

Seimens is supposed to have these. The good ones are fairly expensive,
and they are all very limited in performance. Noise is very complex,
and
all the situations are very random.

Hmmmm, check out the Fenton Silencer, you'll find it in Arthur C. Clark's
"Tales From The White Hart"
Ol' Fenton still had some glitches in it, but the story dates back to the
forties!
Regards,
Tom