A male singer, using his "smooth like butter" voice on songs of romance. Bing Crosby, big in radio's early days, was one; Frank Sinatra, the first teen idol, was another. This is the part of pop music where baritones reign supreme; it has fallen off in an age where raucous tenors and teen markets rule. But it has been an extra arrow in the quiver of rockers, past and present, like Iggy Pop and Jim Morrison, usually minus the "moon june spoon" old school mating-ritual context.