the group by plucking a steady, moving bass line. The drummer perfected the beat with sticks or brushes on cymbals, snare drum, and tom-tom. The bass drum was reserved for unexpected accents called "bombs." The pianist inserted complex chords at irregular intervals to suggest, rather than state, the complete harmonies of the piece. Whereas earlier jazz was mainly diatonic, much of the thinking that informed the new movement was chromatic. Thus the harmonic territory open to the jazz soloist was greatly increased. Bebop took the harmonies of the old jazz and superimposed on them additional "substituted" chords. It also broke up the metronomic regularity of the drummer's rhythmic pulse and made solos played in double-time and having several bars with sixteenth notes. The result was complicated improvisation. Bebop musicians understood the small combo format, which was popular in small group jazz of the 1930's and early New Orleans jazz of the 1920's. Whereas the tunes performed by big band musicians often borrowed the chord changes of popular melodies, upon which they superimposed their own melodic inventions. Charlie Parker's composition "Chasin the Bird," for example, is based upon the harmonic structure of the popular tune "I Got Rhythm." By taking more syncopated and faster rhythms, bebop musicians added more to the standard isometric dance rhythms of swing. Like early New Orleans jazz bands and big bands, bebop musicians usually arranged their tunes to fit either a twelve-measure or thirty-two-measure form. There are many theories about the origin of the word bebop as there are about most jazz expressions. One possibility is that the word "bebop" originated in the jazz musician's practice of vocalizing or singing instrumental melodic lines with nonsense syllables (scat singing). Bebop phrases usually had hard endings with a specific long-short pattern on the end. This rhythm was often vocalized as "rebop" or "bebop." ...
