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traditional music, as well as genres such as
blues and
jazz. In these genres, chord progressions are the defining feature on which melody and rhythm are built.
In tonal music, chord progressions have the function of either establishing or otherwise contradicting a
quality" of the chords. For example, the previously mentioned chord progression, in the key of E
♭ major, would be written as E
♭ major–B
♭ major–C minor–A
♭ major in a fake book or
lead sheet. In the first chord, E
♭ major, the "E
♭" indicates that the chord is built on the
root note "E
♭" and the word "major" indicates that a
major chord is built on this "E
♭" note.
In rock and blues, musicians also often refer to chord progressions using Roman numerals, as this facilitates transposing a song to a new key. For example, rock and blues musicians often think of the 12-bar blues as consisting of I, IV, and V chords. Thus, a simple version of the 12-bar blues might be expressed as I–I–I–I, IV–IV–I–I, V–IV–I–I. By thinking of this blues progression in Roman numerals, a backup band or rhythm section could be instructed by a bandleader to play the chord progression in any key. For example, if the bandleader asked the band to play this chord progression in the key of B♭ major, the chords would be B♭-B♭-B♭-B♭, E♭-E♭-B♭-B♭, F-E♭-B♭-B♭.
The complexity of a chord progression varies from genre to genre and over different historical periods. Some pop and rock songs from the 1980s to the 2010s have fairly simple chord progressions.
32-bar song forms
with one or two chord changes every bar.
Basic theory
scale degrees
are numbered likewise. Thus the chord progression E minor–F–G can be described as three–four–five, (or iii–IV–V).
A chord may be built upon any note of a
type (major, minor, diminished, etc.) Chords in a progression may also have more than three notes, such as in the case of a
seventh chord (V
7 is particularly common, as it resolves to I) or an
extended chord. The harmonic
function of any particular chord depends on the context of the particular chord progression in which it is found.
[2]Diatonic and chromatic chords
The diatonic harmonization of any
", which uses I, IV and V chords).
The same major scale also has three
relative minor key) as do the three major chords, so that they may be viewed as the first (i), fourth (iv) and fifth (v) degrees of the relative minor key. For example, the relative minor of C major is A minor, and in the key of A minor, the i, iv and v chords are A minor, D minor and E minor. In practice, in a minor key, the
third of the dominant chord is often raised by one semitone to form a major chord (or a
dominant seventh chord if the
seventh is added).
In addition, the seventh degree of the major scale (i.e. the leading tone) forms a diminished chord (viio).[4]
A chord may also have
secondary dominant of the V chord (V/V). In some instances, chromatic notes are introduced to
modulate to a new key. This in turn may lead to a
resolution back to the original key later on, so that the entire sequence of chords helps create an extended
musical form and a sense of movement.
Progressions
Although there are many possible progressions, in practice, progressions are often limited to a few bars' lengths and certain progressions are favored above others. There is also a certain amount of fashion in which a chord progression is defined (e.g., the 12-bar blues progression) and may even help in defining an entire genre.[citation needed]
In western
improvisation
.
Common progressions
Simple progressions
, etc.
Alternation between two chords may be thought of as the most basic chord progression. Many well-known pieces are built harmonically upon the mere repetition of two chords of the same scale.[2] For example, many of the more straightforward melodies in classical music consist entirely or mostly of alternation between the tonic (I) and the dominant (V, sometimes with an added seventh), as do popular songs such as "Achy Breaky Heart".[7] The Isley Brothers' "Shout" uses I–vi throughout.[8]
Three-chord progressions
Three-chord progressions are more common since a melody may then dwell on any note of the scale. They are often presented as successions of four chords (as shown below), in order to produce a binary harmonic rhythm, but then two of the four chords are the same.
- I – IV – V – V
- I – I – IV – V
- I – IV – I – V
- I – IV – V – IV
Often the chords may be selected to fit a pre-conceived melody, but just as often it is the progression itself that gives rise to the melody.
Similar progressions abound in
.
Three-chord progressions provide the harmonic foundation of much African and American popular music, and they occur sectionally in many pieces of classical music (such as the opening bars of
).
Where such a simple sequence does not represent the entire harmonic structure of a piece, it may readily be extended for greater variety. Frequently, an opening
tonic chord
, giving a structure of double the length:
Additionally, such a passage may be alternated with a different progression to give a simple binary or ternary form such as that of the popular 32-bar form (see musical form).
Blues changes
Blues progressions influenced a great deal of 20th century American popular music
The
12-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 (and there are many variants), the chord progression is
| I
|
I
|
I
|
I
|
| IV
|
IV
|
I
|
I
|
| V
|
IV
|
I
|
I
|
Blues progressions have also been subjected to densely chromatic elaboration, as in the
Bird blues
.
Steedman (1984) proposed that a set of recursive
"). 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.[10]
1950s progression
Another common way of extending the I–IV–V progression is by adding the chord of the sixth scale degree, giving the sequence I–vi–IV–V or
50s progression
or doo-wop progression.
This progression had been in use from the earliest days of classical music and then generated popular hits such as
Heart and Soul" (1938).
[12]Taken up into the pop mainstream, it continued to be used sectionally, as in the last part of The Beatles' "
Happiness Is a Warm Gun".
[13]Circle progressions
