**FILE** Singer-actor Justin Timberlake attends a gala benefit for the Metropolitan Museum of Art's Costume Institute in New York in May 2012. (Associated Press)
Singer-songwriter Katy Perry attends the eighth annual UNICEF Snowflake Ball at Cipriani 42nd Street on Tuesday, Nov. 27, 2012, in New York. (Evan Agostini/Invision/AP)
Singer-rapper Nicki Minaj performs at the Radio One Hackney Music Festival in Hackney Marshes in east London on Saturday, June 23, 2012. (AP Photo/Joel Ryan)
Singer-songwriter Sheryl Crow attends the Entertainment Industry Foundation's "Unforgettable Evening" in Beverly Hills, Calif., on Wednesday, April 18, 2012. (AP Photo/Matt Sayles)
Singer-songwriter Sixto Rodriguez, who uses only his last name professionally, is the subject of the documentary “Searching for Sugar Man.” Though his career faded in the U.S. in the 1970s, his music was wildly popular in South Africa. (Sony Pictures Classics)
** FILE ** Singer-actress Jessica Simpson poses with her fiance, Eric Johnson, at the Footwear News Achievement Awards at the Museum of Modern Art in New York on Tuesday, Nov. 29, 2011. (AP Photo/Starpix, Amanda Schwab)