Noise Removal Discovery? [CLOSED]

[EPAIII]

While using the Noise Removal tool in V2.0.2 on a Win 7 computer I have observed a curious effect. If the vertical scale for my tracks is set to "Waveform (dB)" as opposed to "Waveform, then the amount of noise reduction is a lot greater. This occurs with identical settings for the tool. I was using the default settings and made the comparison using the "Waveform (dB)" setting to view both results.

I wonder if anybody else has observed this? Can anybody explain it? I don't think this is a bug so I posted it here. But, if it is true, then perhaps something should be included in the instructions.

If it is penitent, I was transferring some vinyl recordings (33 & 1/3s) to digital. Audacity is excellent for this. I love it.

[Gale Andrews]

Do you mean merely that the amount of visual reduction in the waveform is greater? This is expected, because Waveform (dB) is logarithmic . Quiet sounds take up more screen height than in Waveform view, so noise will have more of its pixel height removed in Waveform (dB) than in Waveform view.

Please note the latest Audacity version is 2.0.5: http://audacityteam.org/download/ .


Gale

[EPAIII]

No, no, NO! I said that I looked at, evaluated the difference while using the same viewing mode on both noise reduction attempts on a file/project. On one I had that mode set to "Waveform" WHILE DOING THE NOISE REDUCTION and on another attempt on the SAME file/project I had it set to "Waveform (dB)" WHILE DOING THE REDUCTION. But I used the "Waveform (dB)" viewing mode to evaluate BOTH of these reductions because it gives greater depth. And the reduction that was performed while the using the "Waveform" view clearly had at least 10 dB more noise remaining in the silent areas of the tracks after the reduction as compared to the one performed while that setting was "Waveform (dB)". Not a subtle difference.

And, as I said, the settings for the noise reduction were the same on both attempts.

Paul A.

Do you mean merely that the amount of visual reduction in the waveform is greater? This is expected, because Waveform (dB) is logarithmic . Quiet sounds take up more screen height than in Waveform view, so noise will have more of its pixel height removed in Waveform (dB) than in Waveform view.

Please note the latest Audacity version is 2.0.5: http://audacityteam.org/download/ .


Gale

[steve]

I wonder if anybody else has observed this? Can anybody explain it?

Testing Noise Reduction I get identical results whether the track is shown as the default "Waveform" view or "Waveform (dB)".

Looking at the code, there is no difference between the processing, regardless of which track view is used.

I can't explain your results, but it is not due to anything in the code.

If you apply the same noise profile to different tracks, you may get differing amounts of noise reduction.
If you apply different noise profiles to two identical tracks, you may get differing amounts of noise reduction.

In my tests I applied the same noise profile to identical tracks (the only difference between the tracks was the track view). All tracks produced bit-for-bit identical results.

[EPAIII]

I tried to duplicate my results and post some photos. I could not.

???

I guess I have to get to bed earlier. But I swear it happened at least once.

[steve]

No worries Thanks for the update.
I'll mark this topic as "closed".