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GUIDE: Podcast Creation 3, Cleaning up podcast audio with Audacity6 min read

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This post is part of a series.

audacity_logoLast Update: 1.14.2024

By this point, you have your intro, outtro, and stinger, and your raw audio file of your podcast. Time to clean that thing up using Audacity (instructions on installing in Part 1). You are welcome to try Audacity’s Editing Tutorial, but here’s my steps.

1. Open Audacity and open your audio file.

Hopefully, your audio file is already in mp3 or other Audacity-friendly format. If not, you may try to import it into iTunes and have iTunes create an mp3 version (right click in iTunes > Create mp3 version). You should see something like the image below:

spikes
Click to enlarge

2. Noise Removal

You should do this step before using any of the amplifying steps below – otherwise, you amplify the noise, and then when you try to remove it, you get artifacts, not during the silence, but during the remaining audio.

If you have some background noise like a microphone hiss or buzz, you can remove it this way.

  1. Find a part of the recording where only the noise occurs, and highlight at least 1 second of it.
  2. From the menu, choose Effect > Noise Removal
  3. Click Get Noise Profile
  4. Select the entire track
  5. From the menu, again choose Effect > Noise Removal and Repair > Noise reduction…
  6. Click OK

Advanced

If you want to remove various cable hums (60Hz being the most common in the US, 50Hz in Europe), you can follow this advice:

  1. Eliminate any 60 cycle hum present in the waveform. Go to Effects/Filters/Notch Filter. In the “Presets” box, click on “60Hz + Harmonics.”
  2. The notch width box should be set to “super narrow.”
  3. Click “OK” and the notch filter will remove any 6o cycle hum present. (The filter actually very selectively removes 60 cycle hum + its harmonics, 120, 180, 240, etc.). The frequency ranges filtered out in this step are so narrow that the loss will not be audible.
  4. If you are in a country that uses 50 cycle AC current, instead of the “60Hz + Harmonics” preset selection, choose “50Hz + Harmonics.” If you are sure there is no AC hum present in your waveform, you can forego this step.

3. Trim off clipping and pops

In order for the next step to work, you need to remove the places where audio spikes occurred (when these hit the max volume and distort, that’s called ‘clipping’). However, there are two different types of clipping, and each must be treated differently.

a. Automatic pop removal

Audacity has a great pop removal filter which you can use. The standard settings are fine.

Advanced: Manually removing ‘pop-clipping’

Pops are not just a louder part of the sound you want to record, but a noise from someone hitting the mic, clapping, or otherwise introducing a loud short noise. They usually look like this (second image is zoomed in):

popclip

popclipzoom

Basically, zoom in on each clip, highlight the spike (as higlighted in the image directly above), and click DELETE.

Then, go back and highlight around that segment and listen to it (click SPACEBAR after highlighting to play, or click the play button on the toolbar) and make sure it sounds ok. If it does not, UNDO, then move on to any others and attempt the same. Most of the time you wont’ be able to tell.

b. Removing ‘volume-clipping’ with a hard limiter

If the manual method doesn’t work on some or all of your spikes, you’ve probably got clipping, not from noise, but from your content, like when a speaker moves too close to the mic or shouts. There’s not much you can do to fix distortion, but you can save your listeners’ ears from pain by cutting down the volume of those sections.

Do this.

  1. Select part or all of the track (click the gray area to the left of the track to Select All)
  2. From the menu, choose Effect > Volume and Compression > Limiter
  3. Set dB limit to -4.0
  4. Set Hold (ms) to 10
  5. Set Apply Make-up Gain to No
  6. Click OK

4. Normalizing

Normalizing brings both channels to the same volume (often one is recorded louder than the other), and it also brings quieter recordings or parts up to a more consistent and listenable volume. Do this:

  1. Select the entire track
  2. From the menu, choose Effect > Volume and Compression > Normalize
  3. Make sure all boxes are selected, and the max amplitude is set to -0.1 (default)
  4. Click OK

5. Compression

Compression brings all of your content up to about the same level by reducing the dynamic range of your content. It’s nice. You can check out the tutorial on compression, but for spoken podcasts, I prefer these settings:

compressor

6. Equalizing

To give your audio more depth and clarity, changing some specific sound frequencies (top end and bottom) will make you sound better.

  1. Select your entire track
  2. From the main menu, choose Effect > EQ and Filters > Filter Curve EQ
  3. Bring up the bottom and top ends (easy on the top!) and make it look something like this before you click OK:

equalize

Advanced

There are some built in curves to help you get fun sounds like ‘walkie talkie’ or ‘AM radio,’ and you can download even more, such as the EM78 curve (XML file, import to get curve similar to mine above), and install them using this procedure.

7. Removing speech errors

You can publish your podcast with any or all speech errors, but to sound pro, you might want to go through and delete such things as clicks, pops, ums, stutters, coughs, loud intakes of breath, and long pauses. This takes time, but is worth it.

Advanced

If you cut off part of a phrase, and are left with a sharp start or end to the remaining words, you can soften that using the FadeIn or FadeOut effect.

  1. Highlight the space before or after the audio ‘cliff’ (image below) and a little of the audio (don’t pass the apex)
  2. From the menu, choose Effect > Fade In (or Fade Out

fadein

CONCLUSION

All that’s left now is to add in the intro, outtro, and any stingers.

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