• Blogs
• Forums
• Tradeshows
• Partners
• White Papers
• Podcast Show Notes
• Events

 

Apple Soundtrack Pro Tutorial

Jan 5, 2010 12:00 PM, By Jan Ozer

Noise reduction

Soundtrack Pro's noise-reduction function attempts to remove background noise such as microphone hum and other similar noises from your audio track. I say attempts because it doesn't work with all types of background noises. In addition, unlike normalization and our ambient sound switcheroo trick for pops and clicks, both of which are fairly mechanical and introduce distortion into your clip only if you screw something up, noise reduction is subjective. Careless application will produce a clip that sounds worse than your original clip.

For these reasons, you should never count on fixing background noise in post. In addition, you should do your best to capture adequate levels because large volume adjustments also boost background noise. You can see this in Figure 14, a closeup of the file that I normalized back in Figure 8. When you zoom in, you can see the bushy area around the waveform centerline, which typically represents background noise.

Soundtrack Pro has a two-step noise reduction workflow. First, you identify the noise for Soundtrack Pro, and then you remove it. To identify the noise, select a region in the file that contains only background noise, like the selected region in Figure 14, and then choose Process > Noise Reduction > Set Noise Print.

Then, double-click the waveform to select the entire file, and choose Process > Noise Reduction > Reduce Noise. Soundtrack Pro opens the dialog shown in Figure 15.

My first step is to listen to the sound being removed, because that's the best indicator of whether the adjustment will produce distortion. To do this, click the Noise Only checkbox, and then click Play. While previewing, I adjust the Noise Threshold and Reduction parameters until I hear only the noise that I want to remove and none of the audio that I'm trying to preserve. In this case, if I heard Rod's voice during preview, I'd back off either the Threshhold or Reduction until I can't hear him at all.

Then I'd uncheck the Noise Only checkbox, and play the audio file again, toggling the Preview Effect Bypass button on and off to hear the before and after file. If the audio doesn't sound metallic or otherwise distorted, I click Apply and move onto my next edit.

As a side note, there are multiple schools of thought as to when you should apply noise reduction. Specifically, some producers apply noise reduction before normalization, some after, and some both before and after. I generally normalize first, then apply noise reduction, but you should see what works best with your source audio.

So that's the audio side of the equation. As with brightness adjustments and color correction, these three audio techniques can go a long way toward improving the quality of your work in a pretty short time.

Continue the discussion on “Crosstalk” the Millimeter Forum.
© 2012 NewBay Media, LLC.