Chord progression

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A chord progression (also chord sequence and harmonic progression or sequence), as its name implies, is a series of chords played in order. Chord progressions are central to most modern European-influenced music and the principal study of harmony. Compare to a simultaneity succession. A chord change is a movement from one chord to another and may be thought of as either the most basic chord progression or as a portion of longer chord progressions which involve more than two chords (see shift of level).

Generally, successive chords in a chord progression share some notes, which provides harmonic and linear (voice leading) continuity to a passage. In the common-practice period, chord progressions are usually associated with a scale and the notes of each chord are usually taken from that scale (or its modally-mixed universe).

Common progressions

The most common chord progressions, in the common practice period and in popular music, are based on the first, fourth, and fifth scale degrees (tonic, subdominant and dominant); see three chord song, eight bar blues, and twelve bar blues. The chord based on the second scale degree is used in the most common chord progression in Jazz, II-V-I.

As stated by Tom Sutcliffe on harmony.org.uk:

“… during the 1960's some pop groups started to experiment with modal chord progressions as an alternative way of harmonising blues melodies. . . . This created a new system of harmony that has influenced subsequent popular music.”

“The use of modal harmonies to harmonise the blues came about because of the similarity of the blues scale to modal scales . . . by experimentation with the possible uses of major chords on the guitar. This phenomenon thus probably derives from the characteristics of the guitar and the way it is used in popular music. This is also linked to the rise in the use of power chords.”

Sutcliffe’s hypothesis is that major chord combinations such as: I , bIII , IV, V and bVII cannot be explained in pure modal terms as, in this combination, these don’t exist in the usual modes. They have to be explained as a new harmonic system combining elements from the blues and elements from modality.

The circle of fifths progression is generally regarded as the most common progression of the common practice period, involving a series of descending perfect fifths that often occur as ascending perfect fourths. The circle of fifths makes up many of the most commonly used progressions, such as II6, V, I in major.

Common progressions used in contemporary popular music

Twelve-bar blues

Rewrite rules

Steedman (1984) has proposed a set of recursive "rewrite rules" which generate all well-formed transformations of jazz, basic I-IV-I-V-I twelve bar blues chord sequences, and, slightly modified, non-twelve-bar blues I-IV-V sequences ("rhythm changes").

The original progression may be notated as follows (typical 12-bar blues):

1  2  3  4   5   6  7  8   9  10 11 12

 I/ I/ I/ I// IV/IV/ I/ I// V/ IV/ I/ I

Where the numbers on the top line indicate each bar, one slash indicating a bar line and two indicating a phrase marking, and the Roman numerals indicating the chord function. Important transformations include

replacement or substitution of a chord by its dominant or subdominant:

1 2  3 4   5  6   7    8    9  10 11 12

I/IV/I/I⁷//IV/VII⁷/III⁷/VI⁷//II⁷/V⁷/I/I//

use of chromatic passing chords:

...7    8    9...

...III⁷/bIII⁷/II⁷...

and chord alterations such as minor chords, diminished sevenths, etc.

Sequences by fourth, rather than fifth, include Jimi Hendrix's version of "Hey Joe" and Deep Purple's "Hush":

1        2        3 4  5          6       7 8   9         10      11 12

♭VI, ♭III/♭VII, IV/I/I//♭VI, ♭III/♭VII, IV/I/I//♭VI, ♭III/♭VII, IV/I/I//

These often result in Aeolian harmony and lack perfect cadences (V-I). Middleton (1990, p.198) suggests that both modal and fourth-oriented structures, rather than being "distortions or surface transformations of Schenker's favoured V-I kernel, are more likely branches of a deeper principle, that of tonic/not-tonic differentiation."

Sources

Nettles, Barrie & Graf, Richard (1997). The Chord Scale Theory and Jazz Harmony. Advance Music, ISBN: 389221056X
Middleton, Richard (1990/2002). "Studying Popular Music". Philadelphia: Open University Press. ISBN 0-335-15275-9.
Steedman M.J., "A Generative Grammar for Jazz Chord Sequences", Music Perception 2 (1) (1984) 52-77.

External links

Google spreadsheet of hundreds of 3 chord songs
Guitarz Forever's Three Chord Progressions For Guitar website
Tom Sutcliffe's Chord Progressions in Tonal Music explains how chord progressions work in relation to musical phrases
Harmony.org.uk explains the use of modal harmony in popular music and its origins
Hot Fret's Chord Progression Generator a useful tool for building chord progressions.
Robert Walker's Chord Progression player - paste a chord progression into this Windows tool and it will play it for you (in any tuning you like)