How to get rid of audio noise digitally

If you´re recording sound effects or speech, you´re aware of the number one high quality sound killer… Yes, we´re talking about noise.

Well, rule number one when it comes to recording sound is to avoid any noise and we all know that. But when you´re doing a quickie and you´re PC´s fan is screaming on the recording, then here´s how to get that fixed and still get away with “decent” sound quality…

This is a simple two step process, that you can do all for free. One of my excellent co-workers and friends, Steven Magyar, actually presented me with parts of this really great procedure a while ago – and I´ve been using it ever since.

Step 1

There´s an excellent and popular audio editing software from www.download.com. It´s called Audacity. Just go there, make a search for it and install it.

You can also click on this link to go to the page directly:
http://download.cnet.com/Audacity/3000-2170_4-10058117.html?tag=mncol

Install and run the software, then load your audio file.

Now, use the maginfying glass icons to zoom in a portion of your audio, where your noise is all you hear. Use the left mouse button to drag a selection and use the play icon to check the noise.

It´s important that you DO NOT hear anything else besides the noise…

Next, head over to the Effect menu at the top and select Noise Removal. When the window appears, select Get Noise Profile. Close the Noise Removal Window.

Now, deselect your selection, zoom out and make sure you either have nothing selected or that ALL of your audio is selected.

Go ahead and bring that Noise Removal back up again, and this time select the amount of noise you want to be removed and click on Remove Noise.

Be careful not to remove too much of it, since that will then interfere with the audio quality. In case you removed too much, you can always use the Edit -> Undo function.

When you´re done, save the new audio as a new WAV file.

Step 2

Now that the noise is gone, we want to get a nice, even audio levels for your speech. If you´re doing sound effects, you can probably skip this step. But it won´t hurt to give it a go anyway…

Get the Levelator from the Conversations Network:
http://www.conversationsnetwork.org/levelator

Run it, drag and drop your noise-less WAV file and let the software do its magic.

It will save a new audio file and add “-output” to the filename.

And that´s it!

Have fun with your audio recordings and let me know if this was helpful!
If it was, don´t hesitate to share this technique with your friends…

Thanks a bunch!

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2 Responses to “How to get rid of audio noise digitally”

  1. Cybersox13 June 27, 2010 at 3:48 am #

    Hi, nice bit on using Audacity, but you really should think twice about using the words “High Quality.” While Audacity is a great audio program there are a lot of things that it’s processing simply isn’t able to handle, and I think you’d be hard pressed to find any professional mixer or sound engineer who would call the end result anything much better than “acceptable.” Any form of digital noise reduction is going to change the sound envelope significantly, there’s always going to be some residual artifacts that will exaggerate through the mix process, and even the best stand-alone multi-thousand dollar noise reduction systems are still far from perfect. That’s the reason film studios still go back and post-loop dialog rather than try to clean it up electronically… believe me, it would be a lot cheaper to do it digitally, but even at the current state of the art, digital noise reduction is still a last line of resort, not a cure all.

    It’s far better, in terms of both quality and time efficiency, to address the problem while still in the analog world… simply using a tight capsule mic, putting the mic in a foam lined box and/or putting your mic and computer in separate rooms… will achieve more than any noise reduction system

    See http://wiki.audacityteam.org/wiki/HowAudacityWorks#Noise_Removal

  2. Waldemar Belwon June 27, 2010 at 10:27 am #

    You have a valid point here, and I have to agree with you.

    However, as I pointed out, this is a “quickie” and the best solution is always to record without noise in the first place…

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