Here is a sampling of some of the most active Jazz vocalists of the 1920's, '30's and '40's: Louis Armstrong, Ivy Anderson, Ella Fitzgerald, Bing Crosby, Bessie Smith, Sonny Terry and Ma Rainey. They are backed by equally big-time instrumentalists: Jelly Roll Morton, Duke Ellington, Jimmy Dorsey, Count Basie and Bix Beiderbecke who, according to legend, threw a week's pay on the floor the first night he heard Bessie Smith, hoping her singing would never end.