Easy Noise Reduction with Audacity

By Catherine Pope

January 14, 2021

Once you get into audio and video recording, background noise will drive you absolutely mad. Although there are lots of solutions out there, most of them are very complicated and often expensive, too. My name is Catherine. In this video, I'll show you a simple method for removing background noise in a free tool called Audacity.

If you haven't already made your recording, make sure you leave around 6 seconds of silence at the end. This means Audacity can isolate the noise it's trying to remove. If you've been unable to do this, find a quiet bit in the middle - the longest possible gap.

Make sure there aren't any odd noises in your silent audio, such as coughs, heavy breathing, or general fidgeting. You want a piece of audio with consistent noise.

Finding silence in Audacity

1. Select your silence.

2. Click Effect > Noise Reduction

3. Click Get Noise Profile - this is telling Audacity what to remove.

4. Select the whole recording using Ctrl + A or Cmd + A. This part is important! Unless you select the entire recording, Audacity will only remove the background noise on your selection, which isn't very helpful.

5. Click Effect > Noise Reduction again.

Screenshot of options in Audacity

6. Click Preview to hear the results you'll get with the default settings. It will play the first few seconds of the audio, so that's why you want your background noise sample at the end. You need to hear how the noise reduction affects your voice. You can then tweak these settings to get the optimal effects:

  • Noise Reduction (dB) - this controls the overall amount of noise reduction. Use the lowest possible value, as higher levels will affect the overall quality of your audio and it might sound as though you're trapped down a well.
  • Sensitivity controls how much of the audio is considered to be noise. If it's overly sensitive, it'll get carried away and remove too much of your voice. If it's too low, you'll still get a lot of background hum. So, click Preview again and move the slider up and down [demonstrate]
  • Frequency Smoothing is getting quite technical. Again, play around with it and find what sounds best. I tend to leave this at 6. Higher values can make your audio cleaner, but less clear.

It's fun and illuminating to switch to Residue. This plays you the audio that Audacity is removing, which possibly sounds like you're eating a bag of toffees.

Screenshot of residue option in Audacity

You can't do this with surgical precision, so don't worry if some of your vocals end up in the bin. You're aiming for a trade off between cleaner audio and a clearer vocal.

Make a note of the settings that worked for you, as that'll give you a good starting point next time. I say "starting point" the amount of background noise will vary each time and you'll have to adjust the settings.

You can do a lot more fine tuning in Audacity and in other programs, such as Adobe Premiere. This is a simple a free option, though, if you're just getting started with audio. Have fun!

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