What is the vocal jazz technique that uses nonsense syllables for improvisation?

Scat singing is the vocal jazz technique that uses nonsense syllables for improvisation.

Scat singing is the vocal jazz technique that uses nonsense syllables for improvisation. This technique is using emotive, onomatopoeic, and nonsense syllables instead of words in solo improvisations on a melody.

Louis Armstrong (1901-1971) became known for his scat singing.