When you think of the austere sound of a voice traveling over a few notes, you're thinking of dhrupad, the oldest north Indian vocal style. Slow tempo-ed and somber, dhrupad is introduced by a long non-verbal alap that can last up to an hour before the melody begins. Basically a Hindu art form, the genre deals most often with mythological stories, the deeds of kings, and devotion. Though dhrupad is seen as the quintessential Indian vocal style, it was supplanted in the last century by khyal, a more improvisatory style that begins slowly and gets very fast, allowing for more displays of technical virtuosity. Other vocal styles include the rare, romantic dhammar; the quick, nonsense syllables of tarana, which probably began as a Persian art form; and the lakshan geet, songs that actually teach the singer how to perform a particular raag (melody). While vocalists have traditionally been male, the field has opened to female singers in the last half-century.