B-

Following up his Al Gore documentary “An Inconvenient Truth,” Davis Guggenheim opts for something completely different. No longer focusing on an earth-shaking problem like climate change, he zeroes in instead on a subject that might be interesting, but is surely of lesser import: what makes a rock guitarist, and what makes a rock guitarist unique, or great? “It Might Get Loud” offers an answer by bringing together three players—Led Zeppelin’s Jimmy Page, U2’s The Edge and White Stripes’ Jack White—to talk together and jam, too. The result isn’t likely to snag Guggenheim another Oscar, but it’s interesting enough, even for non-fanatics.

The picture, of course, consists of a good deal more than footage of the trio talking and, eventually, playing together (however briefly), though their swapping of stories and sharing of techniques are pretty irresistible in themselves. It also offers a glance at the three men’s pasts, following White’s beginnings as a furniture uphoalsterer, Edge’s days in a Dublin school band and Page’s years as a London session musician for hire. And it follows them “home”: White visits a Tennessee farm where he plays an old instrument, Edge takes us to his state-of-the-art recording studio, and Page visits the estate where one of Zeppelin’s most famous songs was recorded, commenting on its peculiar acoustic properties. The men also discuss their different attitudes toward technical manipulation of guitar sound.

One gets a real sense of each man as the material builds up, with Page’s amiable gentility, Edge’s quiet self-confidence and White’s cockiness coming through clearly. Their strengths and eccentricities are both touched on, lightly but tellingly. And, of course, their instrument—or rather instruments—are as much stars as they are.

“It Might Get Loud” works not because of the decibel level, but because by bringing together three dissimilar players who share a single passion, it succeeds in demonstrating the expressive possibilities of their common instrument.

Would-be rockers and fans of these three performers will especially appreciate the movie, but others shouldn’t be turned off by it; it presents their human qualities as well as their musical ones.