Pitch shift

Pitch shifting is a sound recording technique in which the original pitch of a sound is raised or lowered. Effects units that raise or lower pitch by a pre-designated musical interval (transposition) are called "pitch shifters" or "pitch benders".

Pitch/time shifting

The simplest methods are used to increase pitch and reduce durations, or vice versa, reduce pitch and increase duration. This can be done by replaying a sound waveform at a different speed than it was recorded. It could be accomplished on an early reel-to-reel tape recorder by changing the diameter of the capstan drive shaft, or using a different motor. As technologies improved later designs of motor speeds could be controlled by electronic servo system circuits. This arrangement using “vari-speed” capstan motors allowed the speed change to be achieved more simply. As for vinyl records, the same thing can be done; placing a finger on the turnable to give friction will retard it, while giving it a 'spin' can advance it.