How to edit an MP3 audio file

Learn how to open and edit an MP3 file using the free Audacity audio editor.

Donald Bell

Nov. 6, 2009 4:32 p.m. PT

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Do you have an MP3 of a song or voice recording that you wish you could trim down or cut out just the part you want? Maybe you finally got around to transferring that old mixtape of yours into iTunes, but you want to get rid of the gaps of silence at the end of each side. Whatever the reason, it can be handy to know how to open up and edit an MP3 file.

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The first thing you'll need is an audio editor that can import MP3 files. Fortunately, one of our favorite audio editors for this also happens to be free. Head over to CNET's Download.com and download a program called Audacity. You can get it for both Mac and PC, it's free, and it's very useful. We actually use it to record all of our CNET podcasts.

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Once you have Audacity installed, go to the program's file menu and select import audio file. Then, find the MP3 file that you want to edit. If the file is in iTunes, you can also drag and drop the file from the iTunes window into an open Audacity window.

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After that, you should see a waveform of the MP3 file. Using the selection tool, you can click around the file and use the play button to preview the sound. Once you've found a part of the file you'd like to delete, just highlight it and hit the delete key. If you want to lift a section out of a longer file, you can highlight the selection, use the copy command from the edit menu, and paste the selection into a new file. If you make a mistake, you can always use the undo command to back out of it.

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Once your edits have been made, you'll want to save the result as a new audio file. By default, Audacity does not export audio to the MP3 format, but there two ways to work around this.

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Once solution is to use the export command in the file menu and save the recording as a WAV file. You can then drag this file into iTunes, and make sure you select the MP3 format from the iTunes Preferences import settings.

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Then use the iTunes Advanced menu to convert the selected audio track to an MP3.

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Another solution is to give Audacity the ability to export MP3s directly. To do this, you'll need to grab the free LAME MP3 encoder extension.

Different versions of Audacity handle LAME integration in different ways, so your best bet is to head to Audacity's online tutorial page on downloading and installing the LAME encoder.