Vocalists were influenced by the bands they sang with, so Billie Holiday learned from Count Basie, Ella Fitzgerald from Chick Webb's orchestra, and Sarah Vaughan from Billie Eckstine's group, and that's how they learned to sing jazz. Ella Fitzgerald was a master at vocal riffing (scatting), but Billie Holiday did not scat at all. Anita O'Day used the technique but Saran and Carmen, very little. But they all improvised, the hallmark of jazz.

In the early 1900's African-American musical traditions mixed with other musical forms in the melting pot of New Orleans. Gradually jazz emerged from a blend of ragtime, marches, blues, and other kinds of music played in this vibrant city. At first, jazz was mostly for dancing but then people began to listen to it.