By David Franz | Monday, April 09, 2012
Noisy audio tracks are one of the most common problems encountered when producing video. Voiceover tracks, dialog tracks, background noise for a scene, and any other type of audio source may include unwanted hum, rumbles, or buzzes. Having high-quality audio is a major factor in producing excellent video content. So, what do you do if the audio for your video project is subpar and includes a lot of noise? Here are some tips on how to reduce the noise on your audio tracks.
First, it’s important to know that these unwanted noises are actually made up of harmonic tones, and to start reducing these noises, knowing what to listen for can help.
60-cycle hum is one of the most common noise problems, and it’s caused by electrical lines in countries like the United States that use power based on a 60-hertz cycle. The technique for getting rid of this noise starts with drastically reducing (or notching out) the 60-hertz content using an equalizer (EQ). But it doesn’t stop there. Because these noises are actually harmonic in nature, there are nodes along the frequency spectrum where the offending hum repeats itself, so you also need to eliminate the upper harmonics of the noise. The upper harmonics are multiples of the main 60-hertz frequency, so you should notch out 120 hertz, 240 hertz, and if needed, 480 hertz as well (60 x 2= 120; 120 x 2= 240; 240 x 2= 480; and another level up would be 480 x 2=960).
If your hum is not a 60-cycle hum, it may be harder to identify immediately the placement of your offending sound’s center nodes. To find visually where your offending frequencies are, Audio for Film and Video with Pro Tools author Scott Hirsch recommends exporting your audio file and using a separate application called Izotope RX.
In the video below, watch how Scott takes care of his problematic hums and buzzes by utilizing a standard issue EQ plug-in in Pro Tools, as well as the Izotope RX application.
For more training on Pro Tools, check out Pro Tools 10 Essential Training. If you’re interested in learning more about audio in general, I recommend checking out our Foundations of Audio courses that include our innovative Get In The Mix Pro Tools session files (no Premium membership required!).
Interested in more?
• All audio courses on lynda.com
• All Pro Tools courses on lynda.com
• All Foundations of Audio courses from Brian Lee White and Alex Case
Suggested courses to watch next:
• Audio for Film and Video with Pro Tools• Pro Tools 10 Essential Training
• Audio Mixing Bootcamp
• Foundations of Audio: Delay and Modulation.
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