Re: [Audacity-devel] [Audacity-quality] Noise Reduction improvement

[Gale A. <ga...@au...>]

| From Steve the Fiddle <ste...@gm...> 
| Sat, 20 Oct 2012 14:30:05 +0100
| Subject: [Audacity-quality] Noise Reduction improvement
> Attached is a patch that increases the window size in the Noise
> Removal effect from 2048 to 4096.
> In my tests this patch typically allows 3 dB (A-weighted) improvement
> to the noise removal for the same quality of remaining sound and only
> about 1% increase to the processing time. This is only a very modest
> improvement, but an improvement nonetheless. If others can confirm my
> test results then I think we should go for this change.
> 
> Note for anyone testing: In most cases the optimum settings will be
> slightly different with the patched version than with the un-patched
> version.

I only tried it on Windows 7 (x64, 2.3 GHz, dual core, 6 GB RAM)
using a track with loud white noise mixed in. Just on that (aural)
evidence, I would say the 4096 window size reduces the noise 
level very slightly without adding more damage.

The optimum setting using 4096 seemed to require a slightly 
lower "Sensitivity" setting than 2048. 

However before testing further, my concern would indeed be 
processing time. On a one hour 48000 Hz stereo track (three
attempts with each window size), I get a processing time of 
about 4 minutes with 4096 compared compared to about 
2 minutes 30 seconds with 2048. I assume your tests are on Linux, 
but if my tests are representative this would have to be a control
in the effect I think. 

  
> On a related issue, there is a feeling among most of the forum crew
> that the Noise Removal effect would be better named "Noise Reduction".
> We regularly receive posts where users clearly have an unrealistic
> expectation that "Noise Removal" should be able to "remove" noise,
> whereas we all know that at best it "reduces" noise. It is unfortunate
> that "Noise Removal" is such a long standing name, but I think that
> the proposed renaming is sufficiently close to the original as to not
> cause confusion for existing users, but may provide a more realistic
> expectation for new users.

FWIW, I'm 0 on this. I can see the point but I think it's probably
too late to make this change without implying something has 
changed for the worse in the effect  

I only have Goldwave and CoolEditPro to hand, but both have 
"Noise Reduction" effects (without controls for Dolby etc.).  




Gale