Justin Bieber has confessed record producers use vocal-tuning software to adjust his singing.

The "Baby" hitmaker is adamant he refuses to use Auto-Tune - the popular audio processor utilized by other stars including Britney Spears - but reveals recording studio engineers correct the pitch of his singing with Melodyne software.

He tells Q magazine, "I don't use Auto-Tune. They tune my vocals - they use Melodyne. But every artist uses Melodyne. Not every artist, but 99 per cent of artists. I like the sound, the perfectness of tuning in the record. No one has completely perfect pitch."