There are many software programs that will allow you to edit your digital audio files. One of our favorites is Audacity, a free program for both Macs and PCs (and Linux). With this editing software you can manipulate the audio file and do things like take out gaps of silence, cut and paste sections of a song, even make the song play backwards.

Here is a simple audio file named “hello.mp3”

Sound editing software displays that sound file as an analog wave looking something like this:

hello sound

“Hello” sound

If you played this sound file, you know that it is a male voice saying “Hello everybody”. The image above is the analog representation of that voice. The real squiggly (not a real technical term) part of the image is the actual sound of the voice. The almost flat line before and after the squiggly part is silence. It’s not 100% silent because there was a bit of background noise that produced little waves. The thicker the waves (or squiggles), the louder the sound. No squiggles = no sound.

To make it truly silent, the sound editing software can ensure it is silent by flattening the wave. Here is what the beginning part of the file looks like before and after silencing. Note that the sound is in stereo, so there are two sets of waves for each (a left and right channel).

Before:
before silence

After:
after silence

Another thing that you can do with the editing software is to remove the gaps of silence entirely. Here’s what the audio file looks like with the silence removed.

remove silence

There are thousands upon thousands of effects that you can use to alter the playback of your original sound. You can explore the particular software that you are using and experiment.

We’ll leave this section with the “hello” sound played backwards.

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