Auto-Tune is a proprietary audio processor made by Antares Audio Technologies. Auto-Tune uses a ph vocoder to fix pitch in vocal and instrumental performances. It is used to hide out of tune singing and mistakes. It lets singers perform perfectly tuned vocal tracks without needing to sing in tune. Its main purpose is to slightly bend sung pitches to the nearest true semitone. Auto-Tune can also be used as an effect to distort the human voice when pitch is raised/lowered a lot.