Stevie Nicks is joining television’s The Voice as an adviser to Adam Levine’s team for the upcoming season. Filming is currently underway on the show’s seventh season. Nicks, the 66-year-old Fleetwood Mac singer, has been working with Levine and his 12 team members as they assign songs and rehearse with the contestants in preparation for the show’s battle rounds. Levine and Blake Shelton will be joined by Gwen Stefani and Pharrell Williams as coaches when the NBC show returns on Sept.