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Change Tempo in Audacity

Posted by admin on Feb 11th, 2010 | 0 comments home title

Audacity offers many great tools for editing audio files. We use Audacity, which is a free and open-source tool, over a number of other apps that we paid good money for. One of the major things that we use it for is to convert audio cassettes onto CDs. Unfortunately, a 90-minute tape will not fit on a CD, which can only hold 80 minutes of audio. In order to get our audio to fit, we use tools in Audacity such as Truncate Silence and what we will cover in this tutorial, Change Tempo.

This effect will change the overall length of the selected portion of the audio file without changing the pitch so that it will not sound like Mickey Mouse. This is a highly effective tool when used correctly and can shorten minutes off of a long audio file and I have a difficult time distinguishing between the original and the edited file.

THE PROCESS

Open the audio file that you would like to shorten (or lengthen) and select the portion of the file that you would like to add the effect to. I typically double-click the waveform and it will select the entire sound file as I want the effect to be applied to the entire file. Once the portion is selected, you go to the Effects menu and choose Change Tempo.

A dialog box will open and you need to choose the amount (percentage) that you want to apply. In my experience, you can change it up to 7 or 8 percent without having too much audible impact. Much more than that, and the sound will move at too great of a pace and it becomes distracting. A handy Preview button is at the bottom of the dialog and you can hear how your amount will sound before applying it to the whole file. Once you choose your amount, select Apply and the effect will be applied to the file.

Once it is done, listen to the end result to be sure that you are happy with the results. If so, save or export the file and you are done.