What kind of title is “Relator”? After first mistaking the word for “realtor,” we thought of a sensitive cousin to Skeletor. Scarlett Johansson has taken no end of flack for the deep, distant-ish singing voice Dave Sitek embedded into their Tom Waits cover album Anywhere I Lay My Head, and since people seem to assume that she’s too pretty and successful to be a real person, it seems a risky idea to give her first new song since that album — this one recorded with hairy singer-songwriter Pete Yorn as part of a fall 2009 disc of duets called Break Up (actually recorded before Anywhere I Lay My Head) — a name evoking a robot that is manufactured to love. But it’s ironic, of course — Scarlett and Pete play a couple struggling to connect, and the language reflects that. So, too, does their singing: Scarlett’s syrupy, dreamy; Pete’s insistent, quavery. It’s a rare kind of interplay. And a rare kind of song: a pieced-together little number that evokes all kinds of classic pop, and passes like warm breeze.