Joan Baez always knew a good song when she heard one. Exactly 40 years ago she took on tour with her a little-known ingrate called Bob Dylan and she’s been championing the cream of left-field American songwriting ever since. The current crop to get the seal of approval on her new album includes Ryan Adams, Caitlin Cary and Gillian Welch, while selections by Steve Earle and Natalie Merchant are also smart choices. Sadly, though, her once pure voice has gone. Worse, she fails to make up for it with the kind of convincing, lived-in patina that has allowed Emmylou Harris and Lucinda Williams to make some of the best records of their careers into their fifties.