On her fifth album, “All Hot Bodies Radiate,” Katie Bull continues to redefine the concept of “jazz vocalist.” She’s no chick singer. Bull’s instrument, her voice, isn’t extraordinarily powerful, plangent or peculiar, and she doesn’t project conservatory-trained technique and tuning. Yet her work mesmerizes and invites repeated listening. That’s because Bull is a singing poet, a writer of yearning, evocative verse that reads as good as it sounds. Delivered freely and fearlessly in a kind of Italianate recicitave, melodic talk-singing, interspersed with pleasing vocal noises, Bull’s ballads take a modernist step beyond anything you’ve heard previously. She’s the rare experimentalist who has the good taste to deconstruct and resurrect tunes like “If I Loved You” and “Ding Dong the Witch Is Dead,” performed here in a vaguely heavy metal provocation. With music this interesting, the Great American Songbook could be gently ushered into retirement.