Bop" for his composition "52nd Street Theme", was the origin of the name bebop. Some researchers speculate that it was a term used by Charlie Christian because it sounded like something he hummed along with his playing. Dizzy Gillespie stated that the audiences coined the name after hearing him scat the then-nameless compositions to his players and the press ultimately picked it up, using it as an official term: "People, when they'd wanna ask for those numbers and didn't know the name, would ask for bebop." Another theory is that it derives from the cry of "Arriba! Arriba!" used by Latin American bandleaders of the period to encourage their bands. At times, the terms "bebop" and "rebop" were used interchangeably. By 1945, the use of "bebop"/"rebop" as nonsense syllables was widespread in R&B music, for instance Lionel Hampton's "Hey! Ba-Ba-Re-Bop". The bebop musician or bopper became a stock character in jokes of the 1950s, overlapping with the beatnik. Instrumentation The classic bebop combo consisted of saxophone, trumpet, double bass, drums and piano. This was a format used (and popularized) by both Parker (alto sax) and Gillespie (trumpet) in their 1940s groups and recordings, sometimes augmented by an extra saxophonist or guitar (electric or acoustic), occasionally adding other horns (often a trombone) or other strings (usually violin) or dropping an instrument and leaving only a quartet. Musical style Bebop differed drastically from the straightforward compositions of the swing era and was instead characterized by fast tempos, asymmetrical phrasing, intricate melodies, and rhythm sections that expanded on their role as tempo-keepers. The music itself seemed jarringly different to the ears of the public, who were used to the bouncy, organized, danceable compositions of Benny Goodman and Glenn Miller during the swing era. Instead, bebop appeared to sound racing, nervous, erratic and often fragmented. While swing music tended to feature orchestrated big band arrangements, bebop music highlighted improvisation. Typically, a theme (a "head," often the main melody of a pop or jazz standard of the swing era) would be presented together at the beginning and the end of each piece, with improvisational solos based on the chords of the compositions. Thus, the majority of a piece in bebop style would be improvisation, the only threads holding the work together being the underlying harmonies played by the rhythm section. Sometimes improvisation included references to the original melody or to other well-known melodic lines ("quotes",