Tutorial: Removing Pops and Clicks and Background Noise in Adobe Audition CS6

So now we're back to the original state. Next we'll try manual noise reduction, which is a two-step process. The first step is to tell Audition what the noise is. Zoom into a small region in the file that doesn't have any speech or other real audio in it, just the noise. Then choose Effects > Noise Reduction > Capture Noise Print (Figure 18, below). By doing so you tell Audition, "That's the noise I want you to remove." When the Capture Noise Print dialog appears, click OK.

Figure 18. Capturing a noise print

Then choose Effects > Noise Reduction/Restoration > Noise Reduction (process) (Figure 19, below).

Figure 19. Processing the noise print

Working in the Effect – Noise Reduction Dialog

Figure 20 (below) shows the Effect – Noise Reduction dialog, where we'll be working for most of the rest of the tutorial. There are a couple of things I recommend doing in this dialog before applying the effect. First, click the Preview button in the lower-left corner. Then click the icon to the left of it, which toggles on and off the effect, and enables you to hear the impact of the effect and to hear if you're removing the noise. Sometimes, at the other side of the equation, you can also hear if you're introducing any distortion by applying the noise reduction effect.

Figure 20. The Effect - Noise Reduction dialog with the power state button (which toggles the effect on and off) highlighted

I've reposted this article's companion video clip below for reference. At the 6:48 mark, you can hear the audio from this clip with the noise reduction effect toggled on and off. It's pretty faint here because of the screencam capture and encoding, but in your own projects, when you capture a noise print for noise reduction and open the Noise Reduction dialog, and then click this button, you should be able to hear—with the effect toggled off—the noise that you're attempting to reduce. When you toggle it back on, you should hear it gone.

Another tool I like to use is Output Noise Only (you'll find it in the lower-left section of the dialog, as shown in Figure 20). When you select the Output Noise Only checkbox, Audition plays only the noise that you've told it to remove. At the 7:36 mark in the clip above, you can hear a little bit of Dr. Sumie's discussion--audio that we don't want to move--which tells us that we're reducing the sound too much. Any time you hear significant amounts of the actual speech, you're removing significant portions of that speech. To tweak the reduction so it doesn't remove audio that you want to keep, move the Reduce by: slider to the left, as shown in Figure 21 (below), until you no longer hear dialogue.

Figure 21. Reducing the Reduce by: parameter until we're no longer removing audio we want to keep

Now we've reduced it so the doctor's speech is barely audible with Output Noise Only selected, and we've gotten to the point where we can remove the background noise and feel comfortable that we're not going to distort the spoken word. In the lower-right corner of the Effect – Noise Reduction dialog, click Apply.

But be sure to deselect Output Noise Only before you apply the effect, or you'll find that you've essentially removed all your audio--that is, you've told Audition to remove everything but the output noise. You never want to do that. If you see a flat line in your waveform after you apply the effect, select Edit > Undo Noise Reduction (Figure 22, below). Then Output Noise Only (which, as you'll understand after making this mistake once, is for preview purposes only), and then apply the effect again.

Figure 22. Undoing the effect after applying it with Output Noise Only selected (or for any other reason)

And you can see in Figure 23 (below) that a lot of the fuzziness that we saw in the quiet areas of the waveform before we applied the effect is now mostly gone. There's still some left but we can feel pretty comfortable that we've removed as much noise as we could without introducing distortion into the spoken word.

Figure 23. The noise-reduced waveform. Flat sections (where there should be no sound) are much less fuzzy.

If you go to the 8:56 mark of the video and listen to the audio with the noise reduction effect applied, you can hear that the audio is much cleaner and most of the unwanted background noise is gone.