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How to Use Noise Reduction on Audio in DaVinci Resolve (With Fairlight)

Audio is an important aspect of creating wonderful videos, but it can be tricky, and recording audio in any space that hasn't been treated can make for some unwanted artifacts and background noises. The good news is that there's tools built-in to DaVinci Resolve that make cleaning up background noise easy. In this tutorial we'll teach you all about the noise reduction filter in DaVinci Resolve's Fairlight audio panel to fight against pesky unwanted distractions in your recording.

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What Does Noise Reduction do?

A noise reduction filter is used to remove unwanted noise from a signal. With Fairlight, you can use a variety of default settings or manually adjust the sound. There's also a great learn feature that allows the program to analyze a section of the signal. Whichever way you decide to edit, you can always manually fine tune the filter to best suite your needs.

Now, as much as I would love to say that a noise reduction filter can fix every problem, I can't. What I mean is that it's best to start with an audio recording that just needs a little help, rather then audio that's pretty much unsalvageable, ie: a subtle fan in the background is probably fixable, and construction noise is probably not. A general rule I try to follow when editing dialogue, especially, is that is less is more. 

How to Use Noise Reduction Filters in Fairlight

The first thing we'll have to do is open up Fairlight and the filter. To do this go to the Mixer, and select Effects, followed by Noise Reduction, then out of the three options presented, select Noise Reduction again.

If you don't see Effects, place your cursor in the mixer above where it says Audio 1 and scroll up/down with your mouse. If it's not there you'll have to go the top right of the mixer where the "..." is and toggle on effects.

Accessing Fairlight's Noise Reduction Filter

Going Over the Filters Layout

Understanding the layout and language used is really the key that makes using this filter easy and practical. Let's start at the top with + and work our way down to Output.

Noise Reduction Layout

Top Half

  • + :  Create a preset.
  • Default < >: There are three preset options you can to choose from: De-HissDe-Rumble, De-Rumble and De-Hiss, and Reset Noise Profile. You can use the arrows (< >)to cycle through the options. This is also where your saved presets will appear.
  • A B: A and B allow you to try out and compare two noise reduction edits against each other.
  • Noise Reduction: Toggle the filter on and off
  • Listen to Noise Only: Allows you focus on the noise in your signal, giving you a better idea of what the filter is doing.
  • Input/Output Meter: The strength of the signal going into the filter vs. the signal being outputted. Sometimes when you apply a noise reduction filter you'll lessen the output of the signal. You can adjust by increasing the gain.
  • Center Graph: Illustrates which frequencies are being effected by the filter.
  • Auto Speech Mode / Manual/Learn: These are the two options you have to use filter. With auto speech mode you can simply play the track and it will automatically make adjustments for you to hear.  Manual mode is a little different. You'll have to let the noise reduction learn the noise/frequency you're trying to effect.

Detection

  • Threshold: This relates to signal to noise ratio. If you ratio is poor, this means you'll have to boost the threshold so that the filter can detect the noise. If your signal to noise ratio is lower, just leaving it at the default setting is a good place to start.
  • Attack: This feature controls how fast or slow the filter reacts to when it hears noise. If your clip has multiple volumes of noise you'll generally be in good spot to leave this at its default. That way the filter can react quickly to the changes. On the other hand, if your clip has noise that's consistent you might not need to filter to react as quickly.
  • Sensitivity: Another great feature to leave at the default to start. Adjusting the sensitivity tells the noise reduction how sensitive it should be to the noise it's listening to. If you think the tool is having a hard time picking up on the frequency you can always boost it a bit.
  • Ratio: Ratio controls the attack time of the signal relative to the attack time of the noise profile. While a faster ratio might help preserve the short spaces between your dialogue, the result can sometimes mess with accuracy of the noise reduction.

Smoothing

  • Frequency: Sometimes you'll get some harmonic ringing while using this tool. Frequency smoothing is a way to compensate for this side effect. You won't always need to use this, but it's handy to have.

Output

  • Dry/Wet: This controls how much of the effect is applied. In audio, dry means that there is little to no effect in the mix, while a wet mix has a good amount present.  This means if you have this set to zero, you will have no noise reduction in your mix. Listening back to your clip will dictate how much you'd like to be present. Too little and you won't hear it, too much your clip might get a little muffled. This is my favourite way to dial in the reduction
  • Level: Remember how I mentioned that noise reduction can impact your output volume? Level allows you to adjust your output to make any correction needed. Remember to use your input.output meters. Note: When boosting the level, it's handy to know that it does so before the effect is applied.

There you have it, an overview on the layout. But what about a practical use? While there is no way to tell you how to use this in way that will be perfect for your clip, lets go over the general ideas and principals that will give the tools to make the most out of noise reduction. 

Reducing Noise in Audio Tracks

Using Auto Speech Mode

After listening to your clip with no effect added, go ahead and turn on the noise reduction as well as your selecting auto speech mode. If your dialogue has space between the talking, the likelihood of the this feature doing a good job in the non dialogue parts (just the noise) is pretty high. That being said, I usually have to adjust the wet/dry and attack. If not, I find that the auto feature is a little too much for when the dialogue is present. Overall, it's so easy to use and making these adjustments is just matter of listening back and not assuming that tool will be perfect. 

Loop Feature

To make adjustments easily, I love utilizing the loop tool. Highlight a section of your clip using the range selection (R) that has both dialogue and the background noise. From here turn on the loop function and use the keyboard shortcut Option+/

Figure 3 - loop

Manual Mode and Learn

There's a caveat for the manual mode/learn. You'll need to have a part of your clip that has only the background noise without any dialouge. This is because Fairlight will not be able to learn the noise/frequency unless it's separate. It would just register the dialogue as part of the problem.

With that in mind, go to your timeline and highlight a section of your clip that features the noise alone. Next use that loop feature again so that the section repeats, this just makes editing easier for you. Now go back to effect page and turn on manual and learn. From there play your clip and Fairlight will do the rest.

Next you'll want to listen back to the whole clip and make adjustments. You'll notice that you could still reduce the noise where there is speaking. Use your ears and the meters to guide you while you make adjustments until you get it just right.

That's it!

Editing background noise isn't too complicated once you know what all the buttons the features do. You'll do yourself wonders by treating each clip as a unique problem to solve rather than something that you can fix quickly with an auto feature or preset.

More Davinci Tutorials

Share Your Craft on the Envato Forums

Last but not least! if you find yourself using noise reduction in Fairlight, let us know by joining the Envato forums. We look forward to seeing your creations!

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