Can't remove noise from this audio clip

[AviUser]

Hi,

I am trying to use Audacity 1.3.3-alpha (9/3/2010) to remove the noise from a karate tv show ripped from VHS tape->DVD->my computer (using VHS->DVD box), but it is not working. For other episodes it worked much better.
Any tips on how to get rid of the noise? I don't think the problem has to do with Audacity beta.

I attached 40 seconds. [removed]


Thanks very much in advance!

[steve]

You're not going to get it perfect - there's too much noise, but you should be able to get a reasonable amount of improvement.
It is much better to work from an original WAV file than from an MP3.

1) Effect > Amplify (default settings)
2) Effect > Nyquist Prompt. Enter the following code and click OK (this will reduce the hum)

Code: Select all

(notch2 
(notch2 
(notch2 s 116 1)
55 1)
180 4)

3) Find a suitable "noise only" section and "get noise profile"
4) Select the whole track and apply Noise Removal with these settings:

Code: Select all

12
0
150
0.1

[AviUser]

Thank you for the response.

I switched to Audacity 1.3.12 (the noise removal feature is slightly less complicated) and followed your steps.
It works so well compared to what I was doing before! The main problem I think was that the breathing noises from fighting got mixed in with the noise, so I just did not apply denoise on those areas to preserve the breathing noises.

Thank you so much!

[steve]

(the noise removal feature is slightly less complicated)

The only differences between the effect in 1.3.12 vs. 1.3.13 are:

1.3.13 has a "Sensitivity" slider - this can help to remove more noise on some more troublesome samples. Normally you would leave this at 0.0, and when you've found the best settings for the other slider, try increasing the Sensitivity a bit to see if it improves the sound - if it does then you will probably also want to decrease the Noise Reduction level and the Attack/Decay settings. If it makes no improvement, leave it at zero.

The Attack/Decay setting in Audacity 1.3.12 does not work - it doesn't do anything. In Audacity 1.3.13, if you notice the background noise "wooshing" after applying the effect, try again with a higher Attack/Decay setting. Normally 0.1 is a reasonable setting.

The "Noise Reduction (dB)" setting is the one that you would normally start with - increasing this will remove more noise but cause more "damage" to the audio (often sounding like a metallic bubbling noise).

The metallic bubbling artefacts can be reduced to some extent by increasing the "Smoothing (Hz) control, but only up to a point.

Start with this setting quite low (about 100) and adjust the Noise Reduction dB setting to get rid of most of the noise (don't try to totally eliminate the noise, that will invariably sound bad, just reduce it to an "acceptable" level). Then if you can hear a metallic bubbly sound, try increasing the frequency Smoothing a bit and see if that improves it. At some point (usually around 150) increasing this slider any further will offer no improvement - aim for the lowest setting that provides the least amount of bubbling.

I normally adjust the settings in this order:

1) Noise Reduction (dB)
2) Frequency Smoothing
3) Attack/Decay
4) Sensitivity - and if better above zero, try reducing 1 and 3 to lower amounts.

[AviUser]

Thanks for the explanation of the new features. I couldn't find much on them.