Reducing noise in Final Cut Pro/Soundtrack Pro

Posted by briansingler on Dec 17, 2010 in Audio, Featured Articles, Video | 3 comments

At some point, no matter how careful you are, you are going to run into a situation in which your audio is plagued with unwanted sound. Soundtrack Pro (part of the Final Cut Studio suite) can take it out. Here’s my step-by-step process.

First things

Noise is, of course, unwanted sound that is obscuring or ruining what want your listeners to be hearing.

Couple of things to remember before we start.

1. Nothing beats getting clean audio on location.
2. Noise reduction works best on constant sources of noise like a hum or hiss or other noise at a certain frequency. The sound of background music or people talking, for example, are bad candidites for noise reduction.
3. The more noise you want to remove, the harder it’s going to be.

Recently, I did a video shoot of a judge in a courtroom. I made the mistake of thinking that I could route audio straight through my DSLR, and it would be OK because of the controlled environment. Bad idea. Because of the horrible auto-gain that plagues DSLRs (I feel another blog post coming) many of my clips were unusable and the ones I could use had hiss in the background.

Here’s before.

With noise present

And after.

With noise removed

Here’s how I got there.

***

Steps

1. Right click on either a single clip or a sequence in Final Cut Pro to send the clip(s) to Soundtrack Pro, using the “Send to” command.

2. In Sountrack Pro, you will see your clip(s); click on one to open in it the File Editor window. (see picture below)

3. Hunt around inside your clip for spot of audio that contains only the noise you want to remove. Find the biggest, cleanest section you can. If there’s other sounds in your selection (a breath, background noise, etc.) the final noise reduction won’t be as good. Your best spots might be a pause after a sentence or some space inbetween words. Once you’ve fond it, highlight that portion of the audio.

4. Go to Process > Noise Reduction > Set Noise Print. Voila, you’ve told Sountrack Pro, what it’s supposed to take out.
5. Note the decibel level of just the noise in your noise print by looking at the meters. In this case, my noise is at about 26 decibels. This info comes in handy later.

6. Highlight your entire clip or portion of the clip that contains the noise you want to take out.

7. Go to Process > Noise Reduction > Reduce Noise

8. The noise reduction HUD will pop up and you can start to take the noise out by hitting the play button.

• In the noise threshold box, pull the slider to match the decibel from your noise print that you jotted down in step 5. This should be a good start, though you may want to adjust it.
• The reduction slider adjusts how much of the noise you are taking out (in percentages). At 100 percent, Soundtrack Pro attempts to remove all the noise.
• The preserve bass and treble slider should be adjusted based on the type of sound you’re trying to keep. In this case, my subject had a high voice, so I pulled the slider all the way to “Preserve Treble.”

9. Aim for the most noise reduction possible without distorting what you do want to hear. This is a compromise. Often with voices, you may have to leave some noise in or else your subject sounds like a chipmunk.

10. Toggle the “Noise Only” button to hear only the noise you are removing. This can be really helpful. If you can still hear some of your subject’s voice, adjust the sliders until you can’t hear them anymore. Then when you turn “noise only” off, you will likely hear some good, clean audio.

11. Hit apply and the noise will be removed from your clip. At this point you can click the “show presets” button and save your noise reductions settings to apply them to the other clips in your sequence, if you have them.

12. Go to File > Export to export your finished audio, being sure to check send to “Final Cut Pro Sequence”

Final

Hope that was helpful. It has saved me a number of times.

Like I mentioned before, capture good audio on set or on location, so you don’t have to do this because inevitably, it takes a toll on your audio, reducing some of the richness and fullness of the sound by removing an entire range of frequences.