Though jazz had long since achieved some limited popularity, it was Louis Armstrong who became one of the first popular stars and a major force in the development of jazz, along with his friend pianist Earl Hines. Armstrong, Hines, and their colleagues were improvisers, capable of creating numerous variations on a single melody. Armstrong also popularized scat singing, an improvisational vocal technique in which nonsensical syllables (vocables) are sung. Armstrong and Hines were influential in the rise of a kind of pop big band jazz called "swing". Swing is characterized by a strong rhythm section, usually consisting of double bass and drums, medium to fast tempo, and rhythmic devices like the swung note, which is common to most jazz. Swing is primarily a fusion of 1930s jazz fused with elements of the blues and Tin Pan Alley. Swing used bigger bands than other kinds of jazz, leading to bandleaders tightly arranging the material which discouraged improvisation, previously an integral part of jazz. Swing became a major part of African American dance, and came to be accompanied by a popular dance called the swing dance.