Chord Progression - Blues Changes

Blues Changes

The twelve bar blues and its many variants use an elongated, three-line form of the I - IV - V progression that has also generated countless hit records, including the most significant output of rock and rollers such as Chuck Berry and Little Richard. In its most elementary form (there are many variants) the chords progress as follows:

I - I - I - I

IV - IV - I - I

V - V - I - I

Again, blues progressions have formed the entire harmonic basis of many recorded songs but may also be confined to a single section of a more elaborate form, as frequently with The Beatles in such songs as "You Can't Do That", "I Feel Fine", and "She's A Woman". They have also been subjected to densely chromatic elaboration, as in the Bird blues.

Steedman (1984) proposed that a set of recursive rewrite rules generate all well-formed transformations of jazz, both basic blues chord changes and slightly modified sequences (such as the "rhythm changes"). Important transformations include:

• replacement of (or addition to) a chord with its dominant, subdominant or the tritone substitution.
• use of chromatic passing chords.
• extensively applying the ii-V-I turnaround.
• chord alterations such as minor chords, diminished sevenths, etc.