The stars of American TV talent show The Voice will kick off the new season next week (beg21Sep15) by performing each other's songs. Gwen Stefani will launch season nine of the show by singing fellow judge and adviser Blake Shelton's Neon Lights, while the country star will tackle Stefani's No Doubt hit Don't Speak. Pharrell Williams will take on Maroon 5's Sugar, while that band's frontman will hit the high notes for Williams' Daft Punk hit Get Lucky.