Charlie Parker began soloing using the scales and arpeggios associated with the chords in the chord progression. Accompaniment In jazz, when one instrumentalist or singer is doing a solo, the other ensemble members play accompaniment parts. While fully written-out accompaniment parts are used in large jazz ensembles, such as big bands, in small groups (e.g., jazz quartet, piano trio, organ trio, etc.), the rhythm section members typically improvise their accompaniment parts, an activity called comping. In jazz, the instruments in the rhythm section depend on the type of group, but they usually include a bass instrument (double bass, electric bass), one or more instruments capable of playing chords (e.g., piano, electric guitar) and drum kit. Some ensembles may use different instruments in these roles. For example, a 1920s-style Dixieland jazz band may use tuba as a bass instrument and banjo as the chordal instrument. A 1980s-era jazz-rock fusion band may use synth bass for the bassline and a synthesizer for chords. Some bands add one or more percussionists. In small groups, the rhythm section members typically improvise their accompaniment parts. Bass instrument players improvise a bassline using the chord progression of the key as a guide. Common styles of bass comping parts include a walking bassline for 1920s-1950s jazz; rock-style ostinato riffs for jazz-rock fusion; and Latin basslines for Latin jazz. Improvised basslines typically outline the harmony of each chord by playing the root, third, seventh and fifth of each chord, and playing any other notes that the composer has requested in the chord (e.g., if the chord chart indicates a sixth chord on the tonic in C Major, the bassist might include the sixth degree of the C Major scale, an "A" note, in their bassline). The chordal instrument players improvise chords based on the chord progression. Chordal instrument players use jazz chord voicings that are different from those used in popular music and classical music from the common practice period. For example, if a pop musician or one from the Baroque music era (ca. 1600-1750) were asked to play a dominant seventh chord in the key of C Major, they would probably play a root position chord named G7 (or "G dominant seventh"), which consists of the notes G, B, D and F, which are the root, third, fifth and flat seventh of the G chord. A post-Bebop era jazz player who was asked to play a dominant