Scat singing
Ella Fitzgerald is considered to be one of the greatest scat singers in jazz history
Originating in vocal jazz, scat singing or scatting is vocal improvisation with wordless vocables, nonsense syllables or without words at all. In scat singing, the singer improvises melodies and rhythms using the voice solely as an instrument rather than a speaking medium. This is different from vocalese, which uses recognizable lyrics that are sung to pre-existing instrumental solos.