Scat singing is vocalizing either wordlessly or with nonsense words and syllables (e.g. "bippity-bippity-doo-wop-razzamatazz-skoobie-doobie-bee-bop-a-lula-shabazz") as employed by jazz singers who create the equivalent of an instrumental solo using only the voice. Also it is a type of voice instrumental. While the use of nonsense syllables in singing long predates scat, scat singing is distinguished by the fact that rather than using the sounds to exactly reproduce the melodic line, improvisations are made with the melody and rhythm, much as in other jazz improvisations. Another form of jazz singing, vocalese, is closely related, but uses lyrics rather than nonsense syllables. Often, rather than improvising melodies, practitioners of vocalese sing lyrics to improvisations by instrumental performers. http://www.answers.com/scat%20singing
