His guitar, when he has one, is a rinky-dink Takamine. No pickup, and the strings haven't been changed since he bought it. He's a solid rhythm guitarist who once fronted the quasi-jam band Jitney Ride and, briefly, the Sharky Farmers, but he drops his pick when he plays and forgets the words to his best songs. He lives in Marlborough, and his voice sounds as if he's smoked too many. He can cover a bit of Nelly and segue into a song about rolling "reefer with loose-leaf paper." But he takes writing seriously, and his best songs, such as "John Denver's Ghost" and "Widowmaker's Son," sound like outtakes from Blood on the Tracks. "You don't like my shadow," Ahearn sings. "It's a victim of the nine-to-five lie/and I'll just wink when you say good-bye." Like his musical heroes, Jack Logan and Bob Dylan, he's prolific, a little obscure, viciously funny and completely original.