Linux Multimedia: Using Audacity to Remove Background Noise

Video isn’t the only media that Linux has made great strides in. Linux is routinely used by big sound and recording studios to record, mix and treat sound for movies and television. Although those tools can be expensive to own, the average user still had a plethora of utilities available that do many of the same things. Let’s take a look at one of the more popular overall sound packages called Audacity.

Download and Installation
In this case, the set up couldn’t be easier. As long as you have a functioning sound card/chip/USB speakers, then your distribution already has everything needed to work with sound except Audacity itself. Easy enough to rectify, let’s pull it down:
sudo apt-get install audacity
OR
sudo yum install audacity


This will create the application entry in your desktop environment to launch Audacity. When you do, you will see something like this:

Audacity Start Screen

Removing Noise
Now, if you have ever recorded sound from your computer or using any microphone, you have had to deal with noise in your recording. Sometimes that noise can simply be edited out with a simple cut in the sound stream, but sometimes a background noise (buzzing, popping, static) can creep in and runs through the course of your entire recording. At that point, you are left with two choices: 1) you re-record the entire stream and hope you have removed the source of that noise (new mic line, turned off the air conditioner, etc) or 2) find a way to remove the noise and only the noise without affecting the rest of the recording.

Here is one of the ways that Audacity can easily rescue you and save you the trouble of re-recording. Using audacity, open any sound or video file (with sound) that has background noise you want to get rid of (Audacity supports a wide range of formats and can export in Ogg, MP3, MP4, RAW, and many others). Once you have the file open, you see a visual representation of the sound file that looks something like this:

Now, we have to define the noise we want to remove. In any sound clip, there are periods of rest (pauses between words or music) that look “smaller” on the timeline than the rest. We use this to define the background noise we want to remove (providing Audacity with a sample of JUST what we want removed). Select at least .2 seconds of that relative silence, but as much as you can. In this clip, we can get almost two seconds worth by clicking and dragging our mouse across the area with what we want removed:

In the menu at the top, now select “Effect” and then “Noise Removal…”. You will see a screen that looks like this one:

Since we have already selected the section containing the sample we want to use, we just need to click the button “Get Noise Profile”. That will close the dialog box you just saw and return you to the main Audacity screen with your sound clip. At this point, Audacity has a profile it can “apply” to our clip to remove the background noise. We need to select the whole clip, we can do that with a “CTL-A” and it will highlight the entire clip. Choose “Effect” and then “Noise Removal…” once more from the menu. This time however, we will simply slick ‘OK’ and Audacity will apply the Noise Profile we just capture to the entire clip. Just click the play button to hear your newly cleaned up audio (and don’t forget to save/export it for posterity).

Final Thoughts
Once again, despite some still insisting that Linux is not ready for the desktop, Linux proves its mettle. There isn’t anything more ‘desktop’ than multimedia and the tools that are available now continue to shine. Hit us up in the comments below and share your Linux Desktop or multimedia success story.

Terrence T. Cox

A veteran of twenty years in Information Technology in a variety of roles. He has worked in development, security and infrastructure well before they merged into what we now call DevOps. He provides training in Linux, VMWare, DevOps (Ansible, Jenkins, etc) as well as containers and AWS topics.

One thought on “Linux Multimedia: Using Audacity to Remove Background Noise

  1. Thank you. It is a very simple tutorial but it works.
    Do you have any tutorial about how to remove background noise from a video using Audacity?

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