Pharrell, Usher Praise Justin Bieber's Voice on Christmas Album

Pharrell paid Justin Bieber the ultimate compliment after he heard his new Christmas album Under the Mistletoe, which arrives tomorrow.

“Listening to your vocals, man, I’m impressed,” said The Neptunes hitmaker while kicking it in the studio with the pop star and Usher. “It’s amazing. I didn’t know that his voice had matured this much. Those runs are really, really clean. A couple times I [got chills].”

Skateboard P co-signed the album, which features collaborations with Mariah Carey, Busta Rhymes, Boyz II Men, and Usher himself. “Ya’ll gotta get this Christmas album. I’m definitely stamping it,” remarked P.

Usher added, “The world is bugging right now ’cause your voice is incredible.”

Bieber is working with Kanye West and Drake on his next studio album Believe, which is due in early 2012. “I feel like this Christmas album is like the iPhone 4S,” said Biebs. “Everyone was waiting for the 5, but we just put out the 4S to give them something real quick.”