Jazz harmony

Jazz harmony is the harmonic idiom or harmonies used in jazz. Similarities between jazz harmony and traditional or common practice harmony or tonality include, notational techniques, (e.g. the musical staff, clefs, accidentals etc.) many chord progressions, and many musical scales. In jazz harmony, however, additional tensions are added to harmonic progressions. Additionally, jazz scales are used as the basis of many harmonic elements found in jazz.

In jazz, chord construction is similar to traditional harmony but includes the wider use of 7th chords as well as chords containing compound intervals. Also, the principles of voice leading, the practice of smoothly moving individual notes of one chord to another, are considerably different from traditional harmony.

The piano and guitar are the two instruments which typically provide harmony for a jazz group. Players of these instruments deal with harmony in a real-time, flowing improvisational context as a matter of course. It is one of the biggest challenges in jazz.

In a big-band context, the harmony is the basis for the writing for the horns, along with melodic counterpoint, etc. The improvising soloist is expected to have a complete knowledge of the basics of harmony, as well as their own unique approach to chords, and their relationship to scales. A style of one's own is made from these building blocks, along with a rhythmic concept.

Jazz composers use harmony as a basic stylistic element as well. Open, modal harmony is characteristic of the music of McCoy Tyner, whereas rapidly shifting key centers is a hallmark of the middle period of John Coltrane's writing. Note that the saxophonist wrote all the chords, and the piano player wrote vamps. Horace Silver, Clare Fischer, Dave Brubeck, and Bill Evans are pianists whose compositions are more typical of the chord-rich style associated with pianist-composers. Joe Henderson, Woody Shaw, Wayne Shorter, Benny Golson, Dizzy Gillespie, and Charles Mingus, are non-pianists who also have a strong sense of the role of harmony in compositional structure and mood. These composers have a musicianship grounded in chords at the piano, even if they are not performing keyboardists.

The harmonic and Roman numeral analyses of chord progressions are also different. Also included in jazz harmony are diatonic and non-diationic reharmonizations, the addition of the V7(sus4) chord as a dominant and non-dominant functioning chord, major/minor interchange, blues harmony, secondary dominants, extended dominants, deceptive resolution, related II-V7 chords, direct modulations, pivot chord modulations, and dominant chord modulations.

Chord Symbology

Jazz harmony recoginizes four basic chord types, plus diminished seventh chords. The four basic chord types are major seventh, minor seventh, half-diminished--which is also known as minor seventh flat five, and dominant. When written in a jazz chart, these chords may have alterations specified in parentheses after the chord symbol. An altered note is a note which is a deviation from the canonical chord tone.

There is variety in the chord symbols used in jazz notation. A jazz musician must have facility in the alternate notation styles which are used. The following chord symbol examples use C as a root tone for example purposes.

Equivalent Symbols		Chord tones in example key		Name
C∆, CM7		C E G B		major 7th chord
C-7, Cm7		C E♭ G B♭		minor 7th chord
C∅, Cm7♭5, C-7♭5		C E♭ G♭ B♭		half-diminished chord
C7		C E G B♭		dominant 7th chord
C°7, Cdim7		C E♭ G♭ B♭♭		diminished 7th chord
Csus7		C F G B♭		dominant or minor suspended 4th chord

Most jazz chord symbols designate four notes. Each typically has a "role" as root, third, fifth, or seventh, although they may be severely altered and possibly use an enharmonic spelling which masks this underlying identity. For example, jazz harmony theoretician Jim Knapp has suggested that the ♭9 and even the ♯9 alterations are functioning in the root role.

The jazz chord naming system is as deterministic as the composer wishes it to be. A general rule of thumb is that chord alterations are included in a chart only when the alteration appears in the melody or is crucial to essence of the composition. Skilled improvisers are able to supply an idiomatic, highly-altered harmonic vocabulary even when written chord symbols contain no alterations.

It is possible to specify chords with more than four notes. For this, the word add is included within the parentheses containing the alteration. For example the chord Cm(∆,add 9) contains the notes (C E♭ G B D).

Melodic Minor Scale

Much of jazz harmony is based on the melodic minor scale, one difference being that the "descending" version of the scale used in classical harmony is not used. The modes of the (ascending) melodic minor scale are the basis for much of jazz improvisation and are variously named as below, using the key of C-minor as an example:

Melodic minor scale tone		Characteristic chord in C-minor		Scale Tones (chord tones in bold)		Scale Name(s)
Ⅰ - C		Cm(∆)		C D E♭ F G A B		melodic minor
Ⅱ - D		Dm7sus(♭9)		D E♭ F G A B C		Phrygian ♯6 or Dorian ♭2
Ⅲ - E♭		E♭∆(♯5)		E♭ F G A B C D		Lydian ♯5
Ⅳ - F		F7(♯11)		F G A B C D E♭		Mixolydian ♯4
Ⅴ - G		G(-6)		G A B C D E♭ F		Mixolydian ♭6 or "Hindu"
Ⅵ - A		A∅		A B C D E♭ F G		Locrian ♯2
Ⅶ - B		B7(alt)		B C D E♭ F G A		Altered, diminished whole tone, or Locrian ♭4

The Ⅶ chord in particular is rich with alterations. As it contains the notes and alterations (Ⅰ, ♭9, m3/♯9, ♭11, ♭5/♯11, ♭13, m7), it is particularly important in the jazz harmonic idiom, notably as a Ⅴ chord in a minor key. For our example key of C-minor, the V chord is G7, so the improvisor would draw upon the G7 altered scale (mode Ⅶ of the Ab melodic minor). A complete ⅱ-Ⅴ-ⅰ progression in C-minor might suggest the following:

ii		D∅		D Locrian ♯2 (mode Ⅵ of the F melodic minor scale)
V		G7(alt)		G altered scale (mode Ⅶ of the A♭ melodic minor scale)
I		Cm(∆)		C melodic minor (mode Ⅰ of the C melodic minor scale)

References

Nettles, Barrie & Graf, Richard (1997). The Chord Scale Theory and Jazz Harmony. Advance Music, ISBN: 389221056X