Fleetwood Mac star Stevie Nicks has been hired as an adviser for coach Adam Levine's team on the U.S. version of Tv talent show The Voice. Nicks will help the aspiring singers choose songs and work on their vocal techniques in preparation for the programme's battle rounds. The seventh season of The Voice premieres this September (14), and also marks the debut of new judges Pharrell WIlliams and Gwen Stefani.