Auto-Tune
Automatic pitch correction of an audio signal, usually vocals, without changing the tempo.
What it means
Auto-Tune refers to the automatic correction of the pitch of an audio signal, most often a vocal recording. Software continuously analyzes the signal's frequency and pulls it toward the nearest semitone of a chosen scale, without affecting tempo, rhythm, or the intelligibility of the lyrics.
The term is technically the trademark Auto-Tune, made by Antares Audio Technologies, but is now used generically for pitch-correction software of any brand. It was developed in 1997 by geophysicist and musician Andy Hildebrand, who adapted an autocorrelation method used in analyzing seismic reflection data to the analysis of pitch.
Musical use
Originally, Auto-Tune was used to smooth out small intonation errors in studio recordings before release, applied subtly enough that listeners would not notice.
A second, clearly audible use became famous: when the correction speed is set very fast, the voice jumps almost instantly from note to note, producing a distinctive metallic sound. This effect was popularized by Cher's Believe (1998) and is often called the “Cher effect”; in hip-hop and R&B of the 2000s, notably with T-Pain, it developed into a stylistic device in its own right.
Auto-Tune should be distinguished from the vocoder, which blends a voice with a synthesized spectrum, and from manual pitch-editing tools, where individual notes are redrawn by hand rather than tracked automatically.
Performance practice
If you use Auto-Tune as a correction tool, set the response time so that only small deviations are pulled into tune; otherwise your voice loses its natural phrasing. If you want the deliberately robotic effect instead, choose a very fast setting and a fixed scale so that transitions between notes are cut sharply.
Don't rely on the software while practicing: a clean approach to pitch and a secure sense of intonation remain the foundation — Auto-Tune only evens out the last small deviations.