Change Speed
From Audacity Manual
To change the tempo of a track without affecting its pitch or frequency range, use
or .Percent Change
If you know how much you want to change the speed of the audio in percent, enter that value here. You can also drag the slider to choose a Percent Change - the input box will update as you drag the slider.
- ( ( (original length) - (target length) ) / (target length) ) * 100 = percent change
For example, if the selection is 3 minutes 21.73 seconds and you need it to be 3 minutes 15 seconds, the calculation is:
- original length = 201.73 seconds, target length = 195 seconds
- ((201.73 - 195) / 195 ) * 100 = 3.451%
The calculation works the same if you want to lengthen the selection, just enter the resulting negative value.
Standard Vinyl RPM
If you have a recording of a record that was played back at the wrong speed you can correct that using these two drop-down menus. In the from drop-down choose the speed the record was played back at; in the to drop-down choose the speed is should have been played back at.