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Topic: Best way to filter noise (blue spectrums) with Audacity? (Read 416 times) previous topic - next topic
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Best way to filter noise (blue spectrums) with Audacity?

I already know that I could use Noise Gate, Low Pass Filter or Noise Reduction. Last is utterly useless since it doesnt seem to handle spectrum selection. The other two do work to some extend but also often reduce the audio quality in general.

On Spectrum I can clearly see what needs to be removed. If I had too much time I could spectral delete this one by one but this is way too tedious. Isnt there a plugin with that you can select a specific spectrum and let it delete all spectrums or interferences similar to what was selected?

Here is also a picture of what I mean, basically I want all these blue spectrums gone, is there a good way to do this?:
https://i.imgur.com/3WpZcDu.png

Re: Best way to filter noise (blue spectrums) with Audacity?

Reply #1
Proper noise reduction starts with a sample of the noise (noise only, no other audio). The software analyzes the noise and creates a pattern. That pattern is marched against the audio stream. Where it matches, it reduces the noise level. When one cannot get a bit of the recording with noise but no music, it becomes much more difficult.

Parameters let one tune the noise sample analysis for different purposes. Other parameters let one set the amount of noise reduction. While the process is not perfect it can make a large (or small) difference, often making the noise inaudible. Some programs are much better at it than others.

CoolEdit, the predecessor to Audition has very good noise reduction, so I guess that Audition also has (or had. Is it still available?). Some earlier versions of Sound Forge had quite useful noise reduction. I used those two programs to remove the background surface noise, as well as considerable power supply hum and electronic equipment hiss, from many hundreds of LPs. There are various other commercial programs that have a very good reputation.

In most cases the results, as least as far as unwanted noise goes, are equivalent to modern recordings on CDs and the formats that followed CDs. It is also the case that I put in hundreds of hours learning to use the functions properly. They are easy to use (if one has the software) but those parameter values, and the way they are applied, are quite significant.