How does Auto-Tune work?

Rebecca Black shot to media stardom in March 2011 with the release of her song ‘Friday’, which made headlines for all the wrong reasons. Many derided the song for its poor lyrics and heavily Auto-Tuned vocals and labelled it one of the worst songs of all time. However, Auto-Tuning technology is often used in this way to tweak dodgy vocals into the polished sound we have come to expect, but how does it work?

Auto-Tune is the brand-name of the pitch-correction software from Antares. Once the key and scale of a recording are set (by the sound editor or by the software), Auto-Tune analyses every note for deviation from target notes in the required scale. For off-key notes, the frequency of the output signal is altered so the pitch is corrected but the recording retains the voice’s characteristics.

This technology is now used in most commercially recorded music and used well, it’s undetectable. Bad auto-tuning can be heard as bubbly or jagged changes in pitch. Best results are achieved by only tuning obviously off-key notes, rather than the whole recording. Now, if only they could work out how to add the software to karaoke machines…

Did you know? Andy Hildebrand invented Auto-Tune in 1997 after a dinner guest challenged him to make her sing in tune.

Auto-Tune's graphical mode displays pitch against time. Editors can just draw in the pitch they require. © Antares Audio Technology