I Got Rhythm Changes in Jazz

I GOT RHYTHM

Standards that are used for jazz often have a 32 bar sequence with an AABA form. It is usual (but not compulsory) for a band to play the melody (head) at the beginning and end of the piece, with improvised solos between over the repeated chord sequence of the melody. One very common chord sequence is that of George Gershwin's I Got Rhythm, though usually with an original head and without the final 2 bar tag. Jazz musicians sometimes refer to this sequence as Rhythm changes. Along with the 12 bar blues sequence, this sequence was almost the anthem of bebop. The chord changes are of course subject to regional/stylistic variations. ex 13a shows a typical sequence based on I Got Rhythm.

ex 13a I Got Rhythm

This sequence shows two important variations:

(a) bars 5-6. (ex 13b-1) This variation uses chord IV minor which is altered to accommodate the passing note descending melody (or bass) line. (See chapter 7 - modal interchange).

(b) bars 13-15. (ex 13b-2) #IV diminished is used to accommodate the passing note ascending melody (or bass) line.

Both are common in Rhythm changes but would not usually appear in the same tune or at least not in the same chorus. I have shown them here together for convenience.

Ex: 13b I Got Rhythm variations at bars 5/6 of each A section.

Some of the many variations used on this sequence:

• The middle 8 can be more complex - V7s could be converted into IIm7-V7s (see below ex 13c)
• b5 substitutes could be used. The cycle of fifths could becomes a cycle of semitones if alternate chords are b5 substitutes (see above tutorial 7)
• The melodic resolution to tonic at the end of each A section could fall either on bar 7 (Lester Leaps In) or on bar 8 as in the original I Got Rhythm melody.

ex 13c: Addition of IIm7 chord to each V7 chord in a cycle.

This can have the same melodic effect as a suspended 4th on each chord - the G of the Am7 resolves to the F# of the D7.