Audacity: removing noise from audio tracks
 

Does anyone have any tips on how to, in Audacity, use the Noise Removal and/or Click Removal tools effectively? I'm trying to use them to remove noise from some live recordings (off DVDs, if that makes any diff), but it's not working very well. The brief spikes of noise sound like the sound of scratches on a record. I fool around with the noise/click removal settings like "threshold," but don't really understand what they mean beyond getting a vague idea from the instructions "lower/higher means more sensitive." If I try an indiscriminate Noise Removal, the result is counterproductive, either eliminating much of the sound or making it extremely scratchy throughout.

If you have just spikes of noise, make a track with white noise (or a noise similar to the original) in those areas and subtract the two.

I once had a crappy free download from iTunes, and it had some type of sin-wave of noise. I remember I tried to recreate the noise as best I could and then I subtracted the two and it worked reasonable well.

I don't have much experience with it myself either, but googling for "audacity" + "noise reduction" and "click removal" pulls up a wealth of information, including youtube videos and these wiki pages:

http://wiki.audacityteam.org/wiki/Click_Removal
http://wiki.audacityteam.org/wiki/Noise_Removal

What I do is a two step process. One is to select an area of noise. Generally it is at the front or end of the track but may be a sample in the middle where little or no music is. It could be as small as a second or maybe less. When you first get that area then go back to the noise remover it should work on entire track.