One night last week the coaches of “The Voice” turned the tables on the press and were able to judge their critics when NBC held a special charity karaoke event for Children's Hospital Los Angeles at Hyde Kitchen in Hollywood, California. All four coaches -- Blake Shelton, Christina Aguilera, Adam Levine and Pharrell Williams -- were in fine spirits as media that usually cover the show faced the music, all singing for charity and getting critiqued by the superstars.