Izotope has a system which does adaptive noise reduction. They call it
"ANR"
http://www.izotope.com/tech/anr/
I heard a demo at AES. They've built a hardware based implementation.
It operates like typical profile-based single-ended NR, but constantly
refreshes the noise profile based on whatever is steady-state in the signal.
It still sounds artifacty, but in the demo anyway it seemed to work well at
adapting to new noise.
-jeremiah
On Sun, Jul 11, 2010 at 10:54 AM, Scott Fraser
<>wrote:
>
>
> <<This is how I understand it. But I think the writer's objection is
> that this process doesn't track changing -noise- levels. For example,
> a passing airplane will be above the thresholds set for the ambient
> noise. The fact is, these algorithms have no intelligence, they don't
> distinguish the sound you want from the sound you don't want except by
> level-in-frequency-band. I think Cedar has some automatically adapting
> algorithms, but I doubt they'd be effective on nature sounds.>>
>
> Right, the adaptive-ness of the algorithm adapts to changing desired
> signal levels, not changing levels of residual noise. However, BIAS
> claims the new version of SoundSoap Pro, version 2, does in fact adapt
> to changing noise levels. We'll have to see about that. There are
> certainly ways around the former method, though. I've occasionally
> done several passes through SoundSoap Pro with differing thresholds,
> then crossfaded amongst the resulting files. Bit of a PITA but
> workable if not too many different noise spectra are presented. For
> the example of a passing airplane I tend to use the Spectral Repair
> mode of iZotope RX, isolating the offending frequency spectra. Lots of
> manual work & not really different than rolling in some tight filter
> bands, although you can get extremely frequency selective with RX,
> without the ringing of a high Q filter. With a nature recording I
> think one could fairly easily do a pass through SoundSoap Pro tuned
> for the aircraft noise, then simply cut that file into place in the
> original, although I'd probably just cut the entire offending section
> of time & discard it.
>
> Scott Fraser
>
>
>
>
>
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jeremiah moore | SOUND |
http://www.jeremiahmoore.com/
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