I’ve been asked a few times now on how I do post-editing on my podcast episodes to get a clean audio file. I thought I’d share with you the steps that I take when I need to quickly do a post-edit before publishing. There are many ways to do post-editing, but these are my personal steps for a quick and easy way of cleaning up audio files. Note that for all of these functions, I am using a free application called Audacity. Load your audio file into Audacity before moving onto these steps.

Removing Noise

One of my personal pet peeves is hearing a droning noise or background feedback in an audio file. Because of this, I make it a point to always remove as much noise as I can with my audio files. Sometimes I am unable to remove all of them, but I try as much as I can.

1. First, identify which part of the waveform you’d like to be your control. Basically, look at the part in the waveform where you are expecting to hear silence, but it shows on the waveform that it’s not silent. Highlight this portion.

2. Navigate to Effect –> Noise Reduction

3. When you get this pop up, click on “Get Noise Profile”. What this does is that it takes your highlight portion and considers that specific section as “noise”.

4. Now, select the entire audio file by using Ctrl+A, or navigating to Edit –> Select –> All. Navigate back to Effect –> Noise reduction.

5. On this screen, take a look at the different settings:

Noise Reduction: This is how much reduction of noise you want to apply. I find that 20 works for my purposes, but your mileage may vary.

Sensitivity: This controls how sensitive you want the filter to detect noise.

Frequency smoothing: In basic terms, this makes it smooth, and I never change it from 3.

Click on OK when you have the settings you want to use.

6. That’s it! Take a look at this waveform. It’s the same waveform I had in step 1, but I applied noise reduction to it and now, the silent portions are completely flattened out.

 

Compressor

Sometimes when you are talking, it’s natural to have some words spoken louder than others, but upon playback it can sound a bit jarring. Another situation where sound levels become an issue is when there are multiple people speaking and everyone speaks at different volumes. The Compressor function helps with this issue by evening out the volume levels so that those who speak soft will be elevated and those who speak loudly will be minimized.

1. Identify a portion where you want to apply compression. I typically do my entire audio clip so it evens everything out, but for the purposes of this tutorial, we’ll use this portion.

2. Navigate to Effect –> Compressor

There’s a lot of information here. Let’s go over each one:

Threshold: This is the “max”, if you will. Basically, anything louder than this threshold will be brought down in volume.

Noise Floor: This is considered the “zero” of the audio. Anything below this level will not be amplified to a higher volume because this is what you consider your “silence”.

Ratio: This is the amount of compression you want to apply to the audio that is over the threshold. I typically set this very high so that my volume range is very controlled.

Attack Time: This sets the duration of how fast the compression starts. A slower duration would mean that the listener can hear the original volume as it starts, then it takes a few seconds for it to compress down. I set this low because I want the compressor to take effect immediately.

Release Time: This is how soon the compressor allows the volume to reach back to normal after the threshold is no longer met.

Make-up gain for 0 dB after compressing: This is used to amplify the lower parts of the audio so it matches up with the compressed part of the audio.

Feel free to start off using the same settings that I have listed here, but again, your mileage may vary. Click OK when you are ready to compress.

3. You’re done! Take a look at the waveform here. The lower volume portion is now looking pretty similar to the higher volume portion. Playback will sound a lot less jarring.

Truncate Silence

This one’s simple. You know those times when you talk and pause in between sentences, or if you are being interviewed and you have to pause and think? To keep things flowing on playback, I try to minimize those portions down, but not too much where it becomes rushed. You can do this pretty quickly by selecting everything and going to Effect –> Truncate Silence.

Level: The level you set here tells Audacity that anything below this level can qualify for silence.

Duration: This is the duration of silence you want Audacity to detect. Basically, in this example, if the audio volume is less than -20 dB and it’s longer than 0.4 seconds, these portions are targeted to truncate.

Action: Truncated Detected Silence does just that, it will truncate the portions longer than 0.4 seconds.

Truncate to: This is the amount of time that those detected segments will be shortened to.

Once you are ready, click ok and you’re done!