Four-time Grammy Award nominee Jewel has signed on as a new judge for the reality competition series for a cappella groups, joining Shawn Stockman, Ben Folds and returning host Nick Lachey. NBC recently greenlighted a fourth cycle of The Sing-Off which is set to air as a holiday strip over several nights later this year. The Sing-Off did solid business for NBC when it aired as a week-long strip in December 2009 and 2010, part of the network’s holiday programming. But when NBC slated it as a two-hour regular weekly series in fall 2011, it fizzled. Now it’s reverting back to that original format. The program showcases the country’s top a cappella groups who have dreams of walking away with the top prize – a recording contract and $100,000. The Sing-Off is produced by One Three Media (a Hearst/Mark Burnett company) along with Outlaw Entertainment and Sony Pictures Television. Mark Burnett (NBC’s The Voice) is the executive producer. Deb Newmyer, Sam Weisman and Jane Mun also are executive producers. Jewel’s debut album “Pieces Of You” became one of the best-selling debut albums of all time. She released a greatest hits album this year featuring duets with Kelly Clarkson and the Pistol Annies and most recently starred as June Carter Cash in the Lifetime movie Ring Of Fire based on Cash’s life.