The journalist Michael Azerrad conducted 25 hours of late-night interviews with alt-rock hero Kurt Cobain for a biography published prior to the singer's 1994 suicide. Thirteen years later, Azerrad has revisited the tapes for the documentary "Kurt Cobain: About a Son," in which Cobain narrates the story of his life over images of three cities that shaped him. We talk with Azerrad and the documentary's director, A.J. Schnack.