When you think of 1940s songs, you likely think of swing and big bands. Jazz became popular and its swing became the pop music of that era. The 1940s gave birth to rock and roll -- not yet accepted by the masses. Popular big band artists from the 1940s include Glenn Miller, Tommy Dorsey and Jimmy Dorsey (brothers), Benny Goodman, and Dizzy Gillespie. The 1940s jazz artists include Rosemary Clooney, Bing Crosby, and Frank Sinatra. A form of jazz called scat also became popular with artists such as Ella Fitzgerald and Cab Calloway. According to the Encyclopedia Britannica, scat music "is a jazz vocal style using emotive, onomatopoeic, and nonsense syllables instead of words in solo improvisations on a melody."