When Howard Levy pulls out an ordinary harmonica, extraordinary sounds emerge. From intricate jazz solos to his "Concerto for Diatonic Harmonica and Orchestra,” he's stretched the little instrument beyond its ostensible limits. “Coltrane is my musical hero, along with Bach,” says Levy. “I just always wanted to try to play some of those tunes on the harmonica." In the 1970s, Levy came up with his own technique to play the full chromatic scale on a diatonic harmonica, and his ongoing forty-plus