The Audio Expert, 2nd Edition

Chapter 12

Pitch and Time Manipulation Processors

Chapter 6 described what Vari-Speed is and how it works, implemented originally by changing the speed of an analog tape recorder’s capstan motor while it records or plays back. Today this effect is much easier to achieve using digital signal processing built into audio editor software and dedicated plug-ins.

There are two basic pitch-shifting methods: One alters the pitch and timing together, and the other changes them independently. Changing pitch and timing together is the simpler method, and it also degrades the sound less. This is the way Vari-Speed works, where lowering the pitch of music makes it play longer, and vice versa. Large changes in tape speed can affect the high-frequency response, ...