pitch shift
An audio effect that raises or lowers the pitch of a sound without changing its duration.
In Depth
Pitch shifting separates pitch from time, allowing audio to be transposed without speeding up or slowing down. This technology enables harmoniser effects (adding parallel harmonies to a voice), creative vocal effects (chipmunk and demon voices), and practical tasks like matching the key of samples. Time-domain and frequency-domain algorithms produce different artefacts. Modern pitch shifting is so transparent that it is routinely used to fix vocal recordings without detection.
Early pitch shifting was done by literally speeding up or slowing down tape, which is why the Chipmunks sound the way they do: their voices are just sped-up human recordings.