Pitch correction

Pitch correction is an electronic effects unit or audio software that changes the intonation (highness or lowness in pitch) of an audio signal so that all pitches will be notes from the equally tempered system (i.e., like the pitches on a piano). Pitch correction devices do this without affecting other aspects of its sound. Pitch correction first detects the pitch of an audio signal (using a live pitch detection algorithm), then calculates the desired change and modifies the audio signal accordingly. The widest use of pitch corrector devices is in Western popular music on vocal lines.

Prior to the invention of pitch correction, errors in vocal intonation in recordings could only be corrected by re-recording the entire song (in the early era of recording) or, after the development of multitrack recording, by overdubbing the incorrect vocal pitches by re-recording those specific notes or sections. Prior to the development of electronic pitch correction devices, there was no way to make "real time" corrections to a live vocal performance in a concert (although lip-syncing was used in some cases where a performer was not able to sing adequately in live performances).

Pitch correction was relatively uncommon before 1997, when Antares Audio Technology's Auto-Tune Pitch Correcting Plug-In was introduced. This replaced slow studio techniques with a real-time process that could also be used in live performance.

Auto-Tune is still widely used, as are other pitch-correction algorithms including Celemony's Direct Note Access which allows adjustment of individual notes in a polyphonic audio signal, and Celemony's Melodyne. Pitch correction is now a common feature in digital audio editing software, having first appeared as a Pro Tools plugin and now being found in products such as Apple GarageBand, Apple Logic Pro, Adobe Audition, FL Studio, Digital Performer, and Steinberg Cubase. MorphTune also provides this functionality. It is also available in the form of rackmount hardware, such as the TC-Helicon VoiceOne. There is also a large stompbox pedal that provides pitch correction in a small device that could be used at a show by plugging the vocal microphone into the pedal and then sending the signal to the PA system. A free VST plugin known as GSnap can also be used to get the same effect. In the Linux FOSS community, Autotalent and Zita-AT1 offer this functionality.

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