Marc J. Zeitlin wrote:

/snip/
Now, that's not to say that SOME amount of ANR can be done with digital
techniques at somewhat higher frequencies than analog ANR can do with
some sophisticated algorithms, but it's hardly "any frequency". I'd be
very surprised if the "wind noise" you mention is more than a few
hundred Hz, and if, in fact, the 850's are "totally useless" in any
propeller driven aircraft, then they've got pretty poor ANR
capabilities. I've never worn them, so I can't comment on them directly.


Mark,

Per the specs from the Telex 850 manual, they provide 12db of active
attenuation between 100 and 2000 Hz. Looking at the Lightspeed 30G
specs, their max attenuation of 36db is centered at 150 Hz, and the 12db
threshold is reached at only 400 Hz. A significant upward shift in
attenuation range for the 850's, IMHO. Looking at the design of the
relative ear pieces, I would guess the Telex microphones sit
considerably closer to the ear than the Lightspeed's.

To appease the pedants running rampant in this group, when I said ANR
could be tuned to *any* frequency, I was incorrect. What I meant to say
was that ANR can apparently be tuned to any frequency desired, within
the realm of human hearing, specifically those frequencies that are
introduced in various aircraft cockpits as "noise". This statement was
to correct a blanket assertion by Mr. Borchert that "ANR is not really
effective at high frequencies..." He is wrong. ANR can be very
effective against the high frequency noise present in some cockpits, if
the headset designer chooses.

Happy Flying!
Scott Skylane
N92054