What is Time Stretching?
Also called: tempo change, warping
Time stretching is changing the speed or length of audio without changing its pitch. It lets you slow a song down to practice or speed a sample up to fit a project's tempo while keeping it in the same key.
Algorithms do this by splitting the audio into small pieces and repeating or removing tiny parts of them, or by working on the audio's frequency content. Different algorithms suit different material: some are better for drums, others for vocals or full mixes.
Modest changes are usually clean. Big changes can bring artifacts such as smeared transients, a metallic tone or a slight echo.
DAWs use time stretching to fit loops and samples to the session tempo, often called warping, and DJ software uses it for key lock while changing speed.
Put it to work
Slow down or speed up a song without changing its pitch.
Change Pitch and Tempo