The I'm Not There soundtrack is the kind of thing that makes music nerds wet their shorts. Just as different actors portray Bobby D. in the flick, some of modern rock and folk's greatest voices—from X legend John Doe and Eddie Vedder to Wilco's Jeff Tweedy and Willie Nelson—take on Dylan's oeuvre on the sprawling two-disc, 34-song soundtrack. And I'm sure hardcore Dylan fans will analyze and dissect all of it with great joy and precision.

But cover albums are often one-offs—curious endeavors listened to for novelty's sake, or catalysts for rediscovering the subject's original work. Ultimately, the enjoyment of a cover depends on two things: how much you like the original song and how much you like the artist covering said song. I mean, however affecting Sonic Youth's "I'm Not There" or Eddie Vedder's "Watchtower," neither can beat, for me, Jim James' (My Morning Jacket) haunting rendition of "Goin' to Acapulco," as I'm a big fan of both the song and James. Then there's the issue of whose voice is truly being employed—in this case, Dylan's or the cover artist's.

Those who already sing like Dylan (Mason Jennings) sound pretty much the same; those who don't either openly (and often uncomfortably) adopt his pigeon-necking inflection and singular cadence (Cat Power) or totally reject it, singing his tunes their own way (Sufjan Stevens' "Ring Them Bells" could easily masquerade as one of his own songs). Then there are those who try to combine the two: On "Simple Twist of Fate," Jeff Tweedy does it quite well, singing in his own tone and, most importantly, with his own emotion, but he also subtly emulates Dylan's vocal upturns. Oddly, Portland's own Stephen Malkmus—who makes three contributions to the record—does all of the above.

If there's one thing Malkmus is known for, it's his unique, lackadaisical vocal style, a quality he probably owes a debt to Dylan for legitimizing. But on "Ballad of a Thin Man"—on which he's accompanied by the record's "house band," the Million Dollar Bashers (a supergroup including Sonic Youth's Steve Shelley and Lee Ranaldo, guitarist extraordinaire Nels Cline and John Medeski, whose fervent Hammond B3 pervades much of the soundtrack)—abandons his distinct style and steps fully into Dylan's shoes. It's a fine cover, but there's little to no Malkmus in it.

Conversely, the ex-Pavement, current-Jicks frontman effectively makes "Can't Leave Her Behind" his own, delivering Dylan's words so much in his own voice that it'll probably turn hardcore fans off. And on "Maggie's Farm," which Malkmus again plays with the Bashers, he reaches a perfect balance. He adopts the original song's vibrant rock attitude, but infuses it with his own smartass quirkery. The song's success, though, is as much due to the song itself as it is to Malkmus—they simply match. Malkmus is the only artist on the soundtrack who gets so many chances to satisfy varying degrees of individuality or impersonation. But seeing as the homage-payee is a true musical chameleon himself, I think Bob would approve.

opens Wednesday, Nov. 21. The soundtrack is out now. Also see

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