[Richard Crowley]

dpierce wrote ...
"Richard Crowley" wrote:
dpierce wrote ...
"Richard Crowley" wrote:
The fundamental theory is the same. But reconstructing
a cancellation signal at higher frequencies requires
more processing horespower (i.e. faster processors).

More "horsepower?" In the limiting case, all the
horsepower that's needed is inverting the phase
of the signal.

At what sampling rate?

Irrelevant. Take a signal, run it through ANYTHING
that inverts the phase. A transformer, an inverting
op amp. No discrete sampling, no DSP of ANY
kind required.

But that's not how noise cancellation works. That method
would merely create acoustic feedback.

Note that consumer noise-cancelling had to wait for the wide
availabity of low-cost DSP computing horsepower.