Rhythm changes
Rhythm changes is a 32-bar chord progression in AABA form that serves as a foundational structure in jazz music, originating from the 1930 song "I Got Rhythm" composed by George Gershwin with lyrics by Ira Gershwin for the musical Girl Crazy.[1][2] This progression, typically played in the key of B-flat major, features a cycle of dominant seventh chords and ii-V-I turnarounds that create a lively, swinging harmonic framework ideal for improvisation.[2][3] The structure of rhythm changes divides into four eight-bar sections: the first A begins with a I-vi-ii-V progression followed by a iii-vi-ii-V, establishing a sense of resolution and tension; the second A repeats this pattern with slight variations; the B bridge shifts to a series of cycle-of-fifths dominant chords (III7 VI7 II7 V7); and the final A returns to the initial pattern, often with an added tag or turnaround.[3] This blueprint, derived directly from Gershwin's tune, simplifies the original 34-bar song by omitting its introductory measures while preserving its rhythmic vitality and melodic contour.[4] Following the popularity of "I Got Rhythm," which became a hit in 1930, notably through Ethel Merman's performance in the musical and Red Nichols's recording, the chord progression quickly evolved into a staple of the swing era and bebop jazz during the 1930s and 1940s.[1][5] Jazz musicians began composing "contrafacts"—new melodies over the existing changes—as a way to practice improvisation without relying on the original lyrics, transforming rhythm changes into one of the most ubiquitous forms in the genre, second only to the blues.[5] By the mid-1940s, it had influenced the harmonic language of modern jazz, with Thelonious Monk's 1957 recording alongside Gerry Mulligan exemplifying its adaptation into more angular, exploratory solos.[1] Numerous iconic jazz standards are built on rhythm changes, including Charlie Parker's "Ornithology" (1946) and "Anthropology" (co-composed with Dizzy Gillespie, 1946), Duke Ellington's "Cotton Tail" (1940), and Sonny Rollins's "Oleo" (1954), each showcasing distinct improvisational approaches while adhering to the core progression.[3][5] These tunes highlight the form's versatility, allowing for substitutions like tritone swaps or modal interchanges that add harmonic complexity without altering its fundamental swing feel.[2] Today, rhythm changes remains a pedagogical cornerstone for jazz education, taught in all keys to develop players' fluency in standard repertoire and spontaneous composition.[3]Origins
Gershwin's Composition
"I Got Rhythm" was composed by George Gershwin in 1930 for the Broadway musical Girl Crazy, with lyrics provided by his brother Ira Gershwin. The song quickly became a hit within the production, showcasing Gershwin's ability to blend sophisticated harmony with accessible, energetic melodies typical of the era's popular songwriting.[6][7] Written in the key of B-flat major, the piece employs a classic AABA form consisting of a 32-bar chorus plus a 2-bar tag (for a total of 34 bars), a structure prevalent in Tin Pan Alley standards that allowed for lyrical repetition and contrast in the bridge. The harmonic framework revolves around cyclical I-VI-II-V progressions in the A sections, creating a sense of forward momentum through tonic-subdominant resolutions, while the bridge modulates through related keys—starting in the dominant before returning via dominant chains—to provide tonal variety and release. This blueprint exemplifies Gershwin's integration of jazz-inflected elements into theatrical music, drawing from the syncopated rhythms and optimistic drive of Tin Pan Alley conventions that emphasized lively, danceable tunes. The 2-bar tag is often omitted in jazz adaptations, simplifying it to the core 32-bar form.[3][4][8][9] This progression's rhythmic vitality, with its driving eighth-note patterns and syncopated accents, reflects Tin Pan Alley's shift toward incorporating ragtime and early jazz influences to heighten the song's exuberant character.[10][11]Early Performances
"I Got Rhythm" premiered on Broadway in the musical Girl Crazy on October 14, 1930, at the Alvin Theatre, where Ethel Merman delivered a powerhouse performance as the highlight number, repeatedly stopping the show with its energetic delivery and her sustained high note.[12][13] The production, produced by Alex A. Aarons and Vinton Freedley, ran for 272 performances until June 1931, establishing the song as an immediate sensation in the popular music scene.[14] The song's rapid ascent was fueled by early recordings and sheet music distribution, with three notable versions released within ten days of the premiere, including Red Nichols and His Five Pennies' rendition featuring Dick Robertson, which peaked at number five on the charts.[15][14] Sheet music, published by New World Music Corporation, circulated widely for home performers, contributing to its status as a Tin Pan Alley hit amid the era's emphasis on accessible popular tunes.[15][16] Early radio broadcasts amplified its reach, such as George Gershwin's own piano performance on the February 19, 1934, "Music by Gershwin" program, which showcased the song's infectious rhythm to a national audience.[17] In the 1930s, "I Got Rhythm" appeared in vaudeville acts, notably when Merman incorporated it into her post-Girl Crazy routines at venues like the Palace Theatre, adapting its Broadway flair for shorter, high-impact performances that thrilled audiences.[18] Revivals and rearrangements emerged, including a 1932 RKO film adaptation of Girl Crazy starring Mitzi Green and Bert Lahr, where Kitty Kelly sang a version of the song amid streamlined staging and new interpolations to suit cinematic pacing.[19] This marked one of the song's earliest transitions to screen, extending its popularity beyond stage revues into broader entertainment formats.[14]Harmonic Analysis
Chord Progression
The standard chord progression for rhythm changes, derived from George Gershwin's 1930 composition "I Got Rhythm," is a 32-bar framework in AABA form typically notated in B-flat major for jazz applications.[2] This progression emphasizes cycles of secondary dominant resolutions and circle-of-fifths motion, providing a versatile harmonic foundation for improvisation.[4] The structure divides into three A sections (bars 1-8, 9-16, and 25-32) and one B bridge (bars 17-24), with each A section built around repeating I–VI–II–V patterns in B-flat major. The following table outlines the complete 32-bar sequence, with chords assigned to individual bars as commonly notated in lead sheets; each bar is typically four beats, and the progression resolves to B-flat major7 at the end of bar 32.[20]| Bars | Chords |
|---|---|
| 1 | B♭maj7 |
| 2 | Gm7 |
| 3 | Cm7 |
| 4 | F7 |
| 5 | B♭maj7 |
| 6 | Gm7 |
| 7 | Cm7 |
| 8 | F7 |
| 9 | B♭maj7 |
| 10 | Gm7 |
| 11 | Cm7 |
| 12 | F7 |
| 13 | B♭maj7 |
| 14 | Gm7 |
| 15 | Cm7 |
| 16 | F7 |
| 17 | D7 |
| 18 | D7 |
| 19 | G7 |
| 20 | G7 |
| 21 | C7 |
| 22 | C7 |
| 23 | F7 |
| 24 | F7 |
| 25 | B♭maj7 |
| 26 | Gm7 |
| 27 | Cm7 |
| 28 | F7 |
| 29 | B♭maj7 |
| 30 | Gm7 |
| 31 | Cm7 |
| 32 | F7 |