Introduction to the 12 Bar Blues

Definition of blues by Merriam-Webster's Online Dictionary:

Main Entry:

blues

Pronunciation:

\ˈblüz\

Function:

noun plural but singular or plural in construction

Etymology:

blue devils

Date:

1741

1 : low spirits : melancholy blues>
2 : a song often of lamentation characterized by usually 12-bar phrases, 3-line stanzas in which the words of the second line usually repeat those of the first, and continual occurrence of blue notes in melody and harmony
3 : jazz or popular music using harmonic and phrase structures of blues

("blues." Merriam-Webster Online Dictionary. 2009.Merriam-Webster Online. 2 April 2009 )


The Twelve Bar Blues:

The twelve bar blues is one of the most common chord progressions in music. It consists of a pattern of I, IV, and V chords. These chords are traditionally played as dominant sevenths (a major triad with a flatted seventh above it), although many artists have adapted the chords into both major and minor keys, and with or without the dominant seventh. The traditional progression consists of four measures of the I chord, followed by two measures of the IV chord, then two more measures of the I chord, then two measures of the V chord, and two measures of the I chord:

I ---- I ---- I ---- I ---- IV ---- IV ---- I ---- I ---- V ---- V ---- I ---- I

This chord progression can be played in any key, which facilitates just about any vocalist's range. Variations on the twelve bar blues include a quick change at measure two (where the I chord is replaced with a IV chord), replacement of the second V chord with a IV chord, and a turnaround at the end of the progression (ending on the V chord) among many others. The eight bar blues (which has many variations), the sixteen bar blues (where the V to IV variation is used, and is played three times before going back to the I), and many other variations of the twelve bar blues are common in popular music. Also, in jazz music, many composers use more complex music theory applied to a blues progression as I will discuss later on.