[hank alrich]

Frank Stearns wrote:

Mike Rivers writes:

On 2/9/2012 8:41 PM, Mxsmanic wrote:

If you know it's actually from a CRT, couldn't you superimpose a signal of
exactly the same frequency and opposite phase and remove it

Actually, I have a better answer than what I just posted. If
you have a sample of the noise that's fairly well isolated,
there are "noise cancellation" programs that, in a more
sophisticated version of what you propose, do what you're
dreaming about. They work by analyzing the spectrum of the
sample of the noise that you want to remove and subtracting
that from the program material. It can work fairly well for

Mike, have you run across a particular package that does this really well?
I've got a couple different venues that have some specific noise spectra
between 90 and 110 hz. (I know; weird frequency range. Seems to be some
sort of "blow across the coke bottle" resonance in the air returns which
appear to be too small for the volume of the halls. In one hall you can
stand about four feet from one of the two returns, release a piece of
paper from chest height, and it quickly sails to the grill and smack,
becomes a prisoner.)

I've messed with the periodic noise removal tool in sound forge and it
seems completely useless for this. (And I have recorded some nice samples
of this noise when it was just me in the hall. Even though it sounds like
periodic noise, perhaps it's too chaotic? The analyzer shows a fair amount
of random bouncing at that hz range; turbulance in the resonate cavity of
the return shaft, no doubt.)

Be curious to hear any product recommendations you might have. Maybe
there's a really smart one that could keep adjusting itself to variations
in the noise spectra.

iZotope RX is alleged to be quite powerful for noise removal.

www.izotope.com/rx/

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