In electronic music

Electronic music

Electronic music is music that employs electronic musical instruments and electronic music technology in its production. In general a distinction can be made between sound produced using electromechanical means and that produced using electronic technology. Examples of electromechanical sound...

, a pitch wheel is a control on a synthesizer

Synthesizer

A synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...

 to pitch bend (portamento

Portamento

Portamento is a musical term originated from the Italian expression "portamento della voce" , denoting from the beginning of the 17th century a vocal slide between two pitches and its emulation by members of the violin family and certain wind instruments, and is sometimes used...

) — to vary the pitch in a continuously variable manner.

The first synthesizer with a pitch wheel was the Minimoog

Minimoog

The Minimoog is a monophonic analog synthesizer, invented by Bill Hemsath and Robert Moog. It was released in 1970 by R.A. Moog Inc. , and production was stopped in 1981. It was re-designed by Robert Moog in 2002 and released as Minimoog Voyager.The Minimoog was designed in response to the use of...

, in 1970.

In the MIDI specification

Musical Instrument Digital Interface

MIDI is an industry-standard protocol, first defined in 1982 by Gordon Hall, that enables electronic musical instruments , computers and other electronic equipment to communicate and synchronize with each other...

, the pitch wheel may send 16,384 possible variation values. The General MIDI

General MIDI

General MIDI or GM is a standardized specification for music synthesizers that respond to MIDI messages. GM was developed by the MIDI Manufacturers Association and the Japan MIDI Standards Committee and first published in 1991...

specification recommends that the total range be ± 2 semitones. Pitch bend range is General Midi Registered Parameter Number 0, 0.