Bob Dorough. You've probably heard him, even if you don't know him by name. If you were a kid growing up in the '70s and watched Schoolhouse Rock, for instance, you're familiar with an infectious little ditty called "Three Is a Magic Number." That's his. Or if you came of age in the next decade, you've no doubt heard "Magic Number," one of the more innovative cuts from De La Soul's debut, which draws from the Dorough classic. The guy is no mere novelty act, though. In the jazz world, he's a heavy hitter -- even if he's never quite gotten his due. Miles Davis thought enough of Dorough's cozy vocal delivery to have him sing on his 1962 Sorcerer album, and his unique lilting vocal style has inspired an array of jazz crooners from Mose Allison to Michael Franks.