Watch The Swing Era (2012) : Full Movie Online Free Jazz began to "swing" as musicians began to adopt swing eighths, the string bass, high hat cymbals, and a looser, more rhythmic feeling . This change occurred gradually starting in the twenties notably with Louis Armstrong, and continued on into the 40's. A lot of the music that came out of this period was played by bands of ten musicians or more. Because of this the swing era is also often known as the big band era.