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Old July 28th, 2014, 11:06 AM   #1
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Removing Background Noise in Adobe Audition

Hey guys,

I'm currently trying to learn how to remove or reducing the background noise of audio. I edit interviews for a TV Channel and sometimes the audio can get rather noising in the background especially after compressing the levels.

So I want to try and learn audio removal/reduction in Audition, so far I've tried it and I seem to get distortion in certain lower areas of the audio that isn't noise, it sounds like the speaker is under water (best way I could put it) but it doesn't sound like that prior to using the noise reduction effect, but I'm not sure what methods I should use to get a reasonable sound without distortion but with the background noise reduced aswell.

Can anyone point me in the direction of some tips or tutorials please?

Thanks
Matt
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Old July 28th, 2014, 11:40 AM   #2
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Re: Removing Background Noise in Adobe Audition

That is simply the nature of the process for the "simpler" forms of noise-removal found in popular software. Ant that is why, if you hang around audio forums like this, you will hear (over and over again until you are nauseated) that "fixing noise in post" is an extremely POOR substitute for getting the signal-to-noise ratio right WHILE RECORDING.

There are very expensive software tools which do a better job at reducing noise, but it doesn't sound like that fits into your economic reality.

There is NO amount of noise-reduction after the fact AT ANY PRICE that is as good as simply using the right microphone in the right place during shooting.
In the "big-leagues" (feature films) they use "dialog replacement" where they haul the actors into a soundproof booth to re-voice their dialog in sync with the picture.
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Old July 28th, 2014, 11:53 AM   #3
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Re: Removing Background Noise in Adobe Audition

Hi Matt,

as a start, try reducing the amount of reduction and use the preview feature to see if it is going to distort too much. I have found that the hollowed out sound can crop up if you are too aggressive at trying to reduce the background. Sometimes, two light passes will work better than one pass. That includes two background samples, one for each pass.

Cheers, Ian
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Old July 28th, 2014, 12:51 PM   #4
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Re: Removing Background Noise in Adobe Audition

Richard is quite right, of course. There is no substitute for selecting the right mic, blocking the action, and getting the mic very close. Well, other than dialog replacement.
Quote:
Originally Posted by Ian Firth View Post
...I have found that the hollowed out sound can crop up if you are too aggressive at trying to reduce the background. Sometimes, two light passes will work better than one pass. That includes two background samples, one for each pass...
I describe this underwater sounding effect as "burbley". As Ian suggests, 2 *or more* light passes can be better than one heavy pass.

You want to do the NR before you do the compression! And the help it gives you might range from 5 to 10% of NR (to the ear). Occasionally 20% for some background sources.

I don't remember whether Audition has a noise gate filter, for some dialog you can gate off the pauses, which is a lot quicker than drawing volume envelopes.

Also, in Audition, those red, green, and yellow dots and the lines above them in the graphical display have some meaning, they are attempting to visually present noise and signal. You need to invest some time in learning what they represent, and what happens when you add points and change the levels in that display.
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Old July 28th, 2014, 03:21 PM   #5
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Re: Removing Background Noise in Adobe Audition

First, +1 on multiple light passes. Select noise where there is a pause, and no useful data present.

You're finding that some of the data involved in the voices is the same frequency set you're removing when you select the noise, leaving "holes" in your audio --- hence, the burble. Fortunately, an excellent feature of Audition NR is the ability to invert the playback --- that is, to listen to what you are REMOVING, rather than what you are keeping. You can clearly hear when you are affecting the good data.

Seth is right, get to understand the noise readout chart; you can tailor the amount of reduction at various frequencies by dragging the output line to conform to the noise level. All is described in the help files.

And compression and EQ generally come at the end of your audio tweaking, not the beginning....
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Old July 28th, 2014, 04:14 PM   #6
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Re: Removing Background Noise in Adobe Audition

Agreed with everything stated above.

You absolutely want to do all your NR first, before applying any compression. The adaptive NR tool distinguishes between "wanted" and "unwanted" audio by comparing levels at any given instant with the "noise profile" that you have loaded first. If your levels are pumping up and down because of compression (or limiting or expansion) then that will really cripple the adaptive NR tool. Even if you use the compression last (as you should), it will raise the level of the background noise relative to the loudest audio. So if you have a noisy track, keep compression to a minimum.

Having said that, it is necessary to listen first, and understand the characteristics of the noise before using any of the removal tools.

For example, if there is a very low frequency room rumble (from air handling equipment) I try to remove that first by building an appropriate low-cut filter (using the FFT tool). Next, if there is a steady low motor hum (typically a bit lower than 60 Hz), or machine whine at a higher frequency (perhaps from an A/C compressor) then I sometimes have better luck removing some of that with a fixed-frequency filter (notch or parametric).

I use the adaptive filter last, and gently, because it can produce those "burbly" artifacts that can ruin music and make voice sound robotic. So I find the key is to remove as much as possible with other tools, before my last one or two passes with the adaptive filter.
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Old July 29th, 2014, 03:46 AM   #7
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Re: Removing Background Noise in Adobe Audition

Thanks for the advice/tips so far, some real helpful things to look into.

Of course, I'd love to have it correct in recording stage but unfortunately I don't record the audio or video as I'm just the editor for TV channel, so I'm trying to learn more about the post stage to try and fix it as much as possible.

Thanks
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Old July 29th, 2014, 10:51 AM   #8
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Re: Removing Background Noise in Adobe Audition

Matt,
I recently needed to do something similar.
I found there are a number of tutorial videos about this. Here's one:

https://helpx.adobe.com/creative-clo.../audition.html

The one I found most helpful was actually a link found in the Adobe Audition Help file on the Noise Reduction effect and correcting "burbly" audio. The big warning there is that the Noise Reduction effect is "destructive", but there is at least one other method...Adaptive Noise Reduction may also be helpful

And I know there are plenty more tutorials out there. I had to remove/reduce the noise of a constantly-running A/C unit. Noise Reduction worked well for my purposes. Once reduced, I simply filed it as a new file name, which left the original still available, and imported the reduced file.

Good luck,
Denis
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