Justin Bieber's 'Balls Have Dropped', Claims Manager

Justin Bieber's manager has revealed that the singer's "balls have dropped".

Scooter Braunt, who looks after the singer, said that Bieber found the recording of his duet with Mariah Carey of 'All I Want For Christmas' difficult as his voice had broken and was not as high as it used to be.

Speaking to Billboard.com, Braunt said: Vocally, his balls have dropped.

He added: "That was the hardest song to do. A year ago that would have been no problem."

Island Def Jam president Steve Bartels discussed the change in Bieber's voice on the new album: "The album really shows his growth as a young man, and his voice has just blossomed. It will pleasantly surprise many people. It's not your typical holiday album."

The track, which can be listened to below on Gigwise, is taken from his forthcoming new album 'Under The Mistletoe', set for release November 1.

Willow Smith and Justin Bieber - live photos