Audacity Forum

Here's an example - I don't know why this happens, but perhaps you can fathom it: Generate a 10 second "Chirp" from 20 Hz to 200 Hz, 0.8 to 0.1 amplitude. Generate 10 seconds of silence. Take the noise profile from the silence and apply it with the default settings. Ideally, nothing should happen (...

And here's a minor UI nuisance I just found... 7) If you change the attack/decay from the default of 0.15, you can't set it back to that value again exactly. (0.10 gets remembered in preferences.) Sorry, I was confused, ignore that. BUT replace it with this more important #7: 7) Doing Get Profile i...

I think noise removal should have this reasonable property: If you apply the effect to the exact selection that was the profile, with zero sensitivity, attack, and smoothing, then the result should just be deamplification. 2.0.5 appears to behave so. I have broken this property in my build. Pink noi...

Then there might be applying Hann or other window before FFT, which would be a fourth smoothing... But I think the "less vicious gating" is a lesser-priority thing to try. Here is why: Remember that what Noise Removal "sees" is like the spectrogram view of your sound, with 2048 sample rectangular wi...

steve wrote:

Paul L wrote:The methods using frequency domain data are different and the reasons for artifacts may be different.

Yes, they may be.
Has anyone tried "gating" the spectrum less viciously?

Are you suggesting a continuous gain curve instead? This sounds like a third smoothing, besides time and frequency!

Nobody has mentioned performance yet. Better results might be bought with more compute time, and advanced settings might control that. Now we use 2048 sample windows stepped by 1024. That ratio needs to be a power of 2, and for acceptable results at least 2^1 I think. Longer windows let us discrimin...

It's well known that hard gating (conventional noise gate) is likely to produce unpleasant artefacts. I am not sure that analogies with single band gating should be pressed too far though. The methods using frequency domain data are different and the reasons for artifacts may be different. So I und...

More like an amputation at the knee! Instead of a continuous curve with discontinuous slope, such as Compressor displays, there would be a constant slope but a jump up at the threshold. That is, graphing dB in to dB out. The gain, which is the difference between that curve and the diagonal, would be...

Would it be correct to say that Noise Removal is working like a multi-band noise gate? "Spectral noise gating" is a description in the manual and wiki. So, yes, 1025 little bands. If you drew the gain curve, it would look like two 1:1 slopes with the left slope lower by the noise reduction setting ...

Look at this, Steve! First picture: your chirp, pink noise, the mix of those two, and the result of noise removal (in my build with fixes) with the pink noise as profile, and extreme 48/0/0/0 settings, viewed with 2048 Blackman-Harris windows (and default gain and range settings for the palette). Wh...