There are known unknowns and there are unknown unknowns, as Donald Rumsfeld liked to say, and bless Speedy Ortiz for somehow shining a light on both. Which is to say: The wiry Massachusetts fuzz bombers have covered a song by German folk singer Sibylle Baier, who so far is largely unrecognized beyond a cult that includes Dinosaur Jr.‘s J Mascis. And they’ve done so in a way that amplifies and distorts, somewhat literally, the original’s eerie sense of mystery. The occasion for Speedy Ortiz’s cover of “Lost Something Beyond the Hills” — recorded in the early ’70s and released on 2006′s Colour Green after Mascis brought Baier to the attention of Orange Twin Records — is Rookie magazine’s new monthly theme, “The Great Unknown.” Aside from the gnarled, gale-force guitars, laid down with assistance from Palehound‘s Ben Scherer at a summer camp guitarist Sadie Dupuis has frequented as both a childhood attendee and a teacher, what’s most striking about the interpretation is how naturally the distant, decades-old material translates into something conversational and sharply contemporary. Unknowns, known or unknown, can be pretty great, sure enough.