Nomenclature

Each chord is described as a series of intervalic relationships to the root of the chord. This provides an accurate and easily understandable basis for working out these chords in each key.

Intervals

The terms used to describe intervals are as follows:

• r = root of the chord
• b2 = minor second = 1 semitone above root
• 2 = major second = 2 semitones above root
• b3 = minor third = 3 semitones above the root
• 3 = major third = 4 semitones above the root
• 4 = perfect fourth = 5 semitones above the root
• #4 = augmented fourth (aka tritone) = 6 semitones above the root
• b5 = diminished fifth = 6 semitones above the root
• 5 = perfect fifth = 7 semitones above the root
• #5 = augmented fifth = 8 semitones above the root
• b6 = minor sixth = 8 semitones above the root
• 6 = major sixth = 9 semitones above the root
• b7 = minor seventh = 10 semitones above the root
• 7 = major seventh = 11 semitones above the root

Compound intervals

Compound intervals are those intervals greater than an octave. They can also be described as an octave plus a simple interval. Note that this is not a complete list of compound intervals but only those that are commonly used in Jazz chords.

• b9 = compound minor second (minor ninth) = 1 semitone + an octave OR 13 semitones above the root
• 9 = compound major second (ninth) = 2 semitones + an octave OR 14 semitones above the root
• #9 = compound augmented second (augmented ninth) = 3 semitones + an octave OR 15 semitones above the root
• 10 = compound major third (tenth) = 4 semitones + an octave OR 16 semitones above the root
• 11 = compound perfect fourth (eleventh) = 5 semitones + an octave OR 17 semitones above the root
• #11 = compund augmented fourth (augmented eleventh) = 6 semitones + an octave OR 18 semitones above the root
• b13 = compound minor sixth (minor thirteenth) = 8 semitones + an octave OR 20 semitones above the root
• 13 = compound major sixth (thirteenth) = 9 semitones + an octave OR 21 semitones above the root

Example

For instance, a chord described as:

r 3 5

contains the root, a major third above the root and a perfect fifth above the root. If this chord were built on Bb (with Bb as the root), it would contain the notes:

Bb(root) D (root + a major third) F (root + a perfect fifth)

However, building the chord on D instead would produce the following chord:

D (root) F# (root major third) A (root + perfect fifth)

Optional extensions to the chords are written in brackets, e.g. (#11). These notes are not absolutely necessary to define the chord to the listener, but may be included to add colour or fill out the sound according to the tastes of the performer.

Many arrangers and composers will write extensions into the chords if they are required.

Voicings

Most chords below are described with each interval a third (major, minor, diminished or augmented) above the previous. This is a standardised method frequently used when describing Jazz chords as it shows them hierarchically, in that the lower intervals (third, fifth and seventh) tend to be more important in defining the chord to the listener than the upper intervals or extensions (9th, 11th, 13th).

However, although it is possible to play the chords as described, it is also possible to use different configurations of the same notes, known as a different voicings, or even by omitting certain voicings.

For instance, the chord known as a "dominant 7th #11" or "lydian dominant" (written e.g. C7#) is described thus:

r 3 (5) b7 9 #11 (13)

Basing this chord on C, hence creating a C7#11 produces the following notes:

C E G Bb D F# A

This is a perfectly acceptable voicing of C7#11, but the same chord type may also be voiced thus:

C E Bb F# A D F#

This voicing omits the perfect fifth (G) and raises the major ninth (D) by an octave. The augmented eleventh (F#) is also played twice in two different registers. This is known as "doubling".

Basic chord types

Descriptions

Major Seventh (written e.g. CÄ OR CMaj7)

r 3 5 7 (9) (6)

Major 6/9 (written e.g. C6/9 OR C6)

r 3 5 9 6

Lydian (written e.g. CÄ#11)

r 3 5 7 (9) #11 (6))

Notes

The above chords, despite the fact that they have different symbols, are often used interchangeably. Often the melody note or other pitched phenomena influences which of the above chord types a performer selects. For example, if the melody note is the root of the chord, including a major seventh can frequently cause a harsh dissonance.

The Lydian chord has a strange quirk, where if you put the root both above and below the augmented eleventh it creates an unpleasant dissonance.

The interval of the sixth is used even though it is described after other compound intervals, and perhaps should also be a compound interval (i.e. 13th). However, convention in Jazz dictates that when describing the major sixth, the simple interval, i.e. 6 is almost invariably used instead of the compound interval, i.e.13. This helps avoid confusion with the dominant thirteenth (see below)

Basic dominant chords

Dominant seventh (written e.g. C7)

r 3 5 b7 (9) (13)

Dominant thirteenth (written e.g. C13)

r 3 (5) b7 (9) 13

Dominant ninth (written e.g. C9)

r 3 (5) b7 9 (13)

Sus (written e.g. Csus OR C7sus)

r 4 (5) b7 (9) (10) (13)

Notes

"Basic", as used above, is used to describe those dominant chords which are based on the major scale.

In many instances, dominant chords than are written as a basic chord (e.g. C13) can be substituted (subbed) for a more complex chord, as long as it remains part of the same group (i.e. dominant chords) and does not clash with the melody note. In the case of C13, this particular symbol is often used if the 13th is found in the melody. If the performer retains the 13th in the chord and/or avoids playing a b13th, in can be subbed for a C13b9. Likewise a C9 can often be subbed for a C+7, as long as the 9th is retained and/or the b9th and #9th is avoided.

Dominant chords tend to sound unstable (the exception being C7#11) and often resolve down a perfect fifth or up a perfect fourth (e.g. C7 tends to resolve onto chords based on F).

Minor seventh (written e.g. C-7, Cmin7 or Cmi7)

r b3 5 b7 (9) (11) (13)

Minor ninth (written e.g. C-9, Cmin9 or Cmi9)

r b3 5 b7 9 (11) (13)

Minor eleventh (written e.g. C-11, Cmin11 or Cmi11)

r b3 5 b7 (9) 11 (13)

Minor thirteenth (written e.g. C-13, Cmin13 or Cmi13)

r b3 5 b7 (9) (11) 13

Dominant #9/#5 (written e.g. C7#9/#5)

r 3 #5 b7 #9

Dominant b9/#5 (written e.g. C7b9/#5)

r 3 #5 b7 b9

These chords can be voiced in a great variety of ways including building the chord on the b7. They very often, but not always, lead to a minor chord built on an interval 4th up from the root. It is also not unusual for either the #9 or b9 or the #5 to be expressed in the melody. (Courtesy of Wikipedia)