When the time came for the Coen Brothers to find the music for their Southern period piece comedy, “O Brother, Where Art Thou?,” they asked record producer T Bone Burnett to lend a hand. They wanted original recordings of old-timey, American folk music. What they came up with was a sprawling mix of authentic bluegrass musicians and contemporary alternative country stars that resulted in a surprisingly successful soundtrack album. Featured on the soundtrack are Emmylou Harris, Alison Krauss, Gillian Welch, John Hartford, Ralph Stanley, David Rawlings, and Chris Thomas King, among others.