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Removing Background Noise from Audio Files with Audacity

Posted: Sun Jan 20, 2008 1:41 am
by STATiK-04
This was originally a tutorial for voetsak, and it seemed to help her alot, so I thought I would repost it here.
This is to remove Backgroud noise from a sound file (the Shhhhh/Hiss/Humm), not an instrument, vocals, etc.
The program used in this tutorial is Audacity. (click to download)
It's a free, open source software for recording and editing sounds in Linux, Mac OS X, and other operating systems.
I have recorded a song off an analogue radio, as I knew that would produce plenty of background noise
1) First things first, open up the Audio file in question.

Next click and drag over a selection of audio where you know it should be JUST SILENCE, but there is "SHHHHHH" instead (In other words, there should be no actual music here at all, just SHHHHH. This would most likely be near the end of the track).
3) Now open up the "Effect" menu and select "Noise Removal".
4) Now select "Get Noise Profile", this will obtain a profile of what is the unwanted noise.
5) Next select the pieces of the audio track that has the unwanted noise. Chances are that the whole audio file is writhe with unwanted noise, so click where indicated in the picture to select ALL THE AUDIO in the track.
6) Now go back to the "Effect" menu and select "Noise Removal" again. This time we are going to tinker with the Threshold of the noise removal. Press preview to hear about 5 seconds of preview of how it will sound when the noise is removed. Keep alternating between the preview button and adjusting the slider until the optimal setting is found. Click "Remove Noise" when done.

7) After the noise has been removed, have a little listen to the whole track. If you don't like the quality of it, simply Undo the Noise Removal (Ctrl + Z), and redo step 6.

8) Now we are going to Export (save) our new audio file. The proffered setting is WAV, that way you don't lose any quality through compression, plus WAV is compatible with basically everything. The next best setting would be FLAC. It has the same quality as WAV, but takes up less HD space. I'm going to proceed with saving as WAV, as FLAC has less codec support in Default windows programs.

Simply open up the "File" menu and select "Export as WAV..."

Now select the location where you would like your file to be kept, and also give it a name...
10) Now it will export the file to a WAV audio file.
Now all that's left to do is to play it in your Media Player of choice ;)

This does not completely remove the noise from the audio, it just "masks" it from being heard as best as possible.

Posted: Sun Jan 20, 2008 6:54 am
by voetsak
This just shows how kind and helpful people are at STF.
See how much trouble Static Sleep went to, to teach me "Take out SSSHHHH For Dummies"
Thanks heaps Stat.

Posted: Sun Jan 20, 2008 7:58 am
by .:jOe:.
Nice guide :)

Although I know you are talking about Audacity as the program you are using, it wouldn't hurt to mention it, perhaps in the topic title?

Posted: Sun Jan 20, 2008 8:18 am
by STATiK-04
Noted and Edited ;)

Posted: Sun Jan 20, 2008 8:26 am
by slavernicus
Thanks Static I have a lot of old lectures on tape I want to rescue.
(and thanks j0e for the missing piece of the jigsaw)

Posted: Sun Jan 20, 2008 8:56 am
by STATiK-04
Hope it helps. If anyone feels anything is missing tell me and I'll try and improve the tutorial.

Posted: Fri Feb 15, 2008 10:20 am
by Andrei
Moved to tutorials.

Re: Removing Background Noise from Audio Files with Audacity

Posted: Sun Apr 10, 2011 12:42 pm
by soporific
is awesome, thanks for this