When you find yourself singing along to your favorite rock'n'roll songs, you're probably not singing along with a front man like David Bowie or Bruce Springsteen. You're probably singing along with their backup singers. http://www.youtube.com/watch?v=tWyUJcA8Zfo The documentary film, “20 Feet From Stardom,” seeks to tell the story of backup singers whose stories often go unsung. Morgan Neville, the director of “20 Feet From Stardom,” joins Host Frank Stasio today on The State of Things to discuss the making of the film.