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In jazz and jazz harmony, "rhythm changes" refers to the chord progression occurring in George Gershwin's song "I Got Rhythm". This pattern, "one of the most common vehicles for improvisation," forms the basis of countless (usually uptempo) jazz compositions, was popular with swing-era musicians: It is found in "Shoeshine Boy" (Lester Young's 1936 breakout recording with Count Basie) and "Cotton Tail" written by Duke Ellington in 1940, as well as Charlie Christian's "Seven Come Eleven", Dizzy Gillespie's "Salt Peanuts", and Thelonious Monk's "Rhythm-a-Ning", for instance. The earliest known use of rhythm changes was by Sidney Bechet in his September 15, 1932 recording of "Shag" with his "New Orleans Feetwarmers" group.
Contents
History
This progression's endurance in popularity is largely due to its extensive use by early bebop musicians. The chord changes began to be used in the 1930s, became extremely common in the '40s and '50s, and are now ubiquitous. First, "I Got Rhythm" was by then already a popular jazz standard; second, by listening to the song and writing a new melody over its chord changes, thereby creating a composition of a type known as a contrafact, a jazz musician could claim copyright to the new melody rather than acknowledge Gershwin's inspiration and pay royalties to his estate.
Today, mastery of the blues and rhythm changes are "critical elements for building a jazz repertoire".
Application
The "rhythm changes" is a thirty-two-bar AABA form containing four eight measure sections. In roman numeral shorthand, the original chords used in the "A" section are
a two bar phrase (I−vi−ii−V) played twice, then
In a jazz setting the changes are usually played in the key of B♭ with various chord substitutions. Here is a typical form for the A section with various common substitutions:
The "bridge" consists of a series of dominant sevenths that follow the circle of fourths (ragtime progression), sustained for two bars each and thus conveying the sense of a shifting key center:
This is known as the Sears Roebuck bridge, named after Sears, Roebuck and Co.
The B section is then followed by the second 8 bars of the A section
Variant versions of changes are legion due to substitutions: bebop players, for instance, would often superimpose series of "two-fives" (passing sequences of minor seventh and dominant seventh chords) or other substitutions for interest or in order to discourage lesser musicians from sitting in on the bandstand. The B section may appear as follows:
or it may be lifted out of this progression and used in the middle of another piece as follows:
The component A and B sections of rhythm changes were also sometimes used for other tunes. For instance, Charlie Parker's "Scrapple from the Apple" and Juan Tizol's "Perdido" both use a different progression for the A section while using the Rhythm changes B section. "Scrapple from the Apple" uses the chord changes of "Honeysuckle Rose" for the A section, but replaces the B section with "Rhythm"'s III7–VI7–II7–V7 bridge. Other tunes, such as Sonny Stitt's "The Eternal Triangle" and the theme from "The Muppet Show", use the A section of "Rhythm" but have a different bridge. Tadd Dameron's "Good Bait" uses the A section of the Rhythm changes but a different progression for the bridge. Sometimes in rhythm changes tunes, the B section is left free for improvisation even during the head (e.g. in Sonny Rollins' "Oleo").
Examples
The following is a partial list of songs based on the rhythm changes: