- Barry Kernfeld
- and Allan F. Moore
The underlying harmonic structure of the blues. In the broad sense, the term can refer to the harmonic basis of any piece called a Blues (an exhaustive survey of these progressions can be found in Dauer), but it must be noted that in an attempt to capitalize on the blues craze of the early 1920s, popular songwriters used ‘blues’ in the titles of pieces whose harmonies bear no relation to that of the blues progression (e.g. Limehouse Blues). In the narrow sense, it refers to a flexible, cyclic 12-bar structure, consisting of three four-bar phrases with the chord pattern shown in ex.1. Many variants of this pattern are possible: frequently IV is used in place of I in bar 2, or in place of V in bar 10. Country blues guitarists characteristically vary the rhythms of the basic progression, and sometimes maintain a tonic drone on the bass strings; in this case a blues harmonic progression may be intimated by the vocal and treble-string melodies....