Lydian chord

In jazz music, the lydian chord is the major 7♯11 chord,^[1] or ♯11 chord, the chord built on the first degree of the Lydian mode, the sharp eleventh being a compound augmented fourth. This chord, built on C, is shown below.

${ \override Score.TimeSignature #'stencil = ##f \relative c' { \time 4/4 <c e g b fis'>1 } }$

This is described as "beautiful" and "modern sounding."^[1] The notes that make up the Lydian chord represent five of the seven notes of the Lydian mode, and the ♯11 at the top of the chord is the ♯4 (one octave higher) that distinguishes the Lydian mode from the major scale.

Major 7♯11 may also refer to the Lydian augmented chord, an augmented seventh chord with augmented fourth appearing in the Lydian augmented scale.^[2]

${ \override Score.TimeSignature #'stencil = ##f \relative c' { \time 4/4 <c e gis b fis'>1 } }$

In a chord chart, the notation "Lydian" indicates a major family chord with an added augmented eleventh, including maj7♯11, add9♯11, and 6♯11.^[1]

Harmonic function

Lydian chords may function as subdominants or substitutes for the tonic in major keys.^[3] The compound interval of the augmented eleventh (enharmonically equivalent to ♯4, the characteristic interval of the Lydian mode) is used since the simple fourth usually only appears in suspended chords (which replace the third with a natural fourth, for example C^sus4). The fifth can be omitted to avoid creating dissonance with the ♯4; this is usually not specified in chord naming.

${ \override Score.TimeSignature #'stencil = ##f \time 4/4 <c' e' b' fis''>1 <c' e' g' b' fis''>1 }$

Cmaj^7♯11 (C–E–(G)–B–F♯), with fifth omitted and included

The dominant 7♯11 or Lydian dominant (C^7♯11) comprises the notes:

r, 3, (5), ♭7, (9), ♯11, (13)

(Note that in jazz lead sheet notation, upper extensions (intervals beyond the 7th) aren't named unless they are altered; alternatively, when including the 9th and 13th this chord could be called a C^13♯11.)

Basing this chord on the pitch C results in the pitches:

C, E, (G), B♭, (D), F♯, (A)

${ \override Score.TimeSignature #'stencil = ##f \time 4/4 <c e bes fis' a' d' fis''>1 }$

A voicing of C^7♯11 (C–E–(G)–B♭–D–F♯–A), with fifth omitted and the ♯4 doubled

The same chord may also be voiced:

C, E, B♭, 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".

References

^ ^a ^b ^c Juergensen, Chris (2006). The Infinite Guitar, p.50. ISBN 1-4116-9007-9.
^ Munro, Doug (2002). Jazz Guitar: Bebop and Beyond, p.39. ISBN 978-0-7579-8281-1.
^ Miller, Scott (2002). Mel Bay Getting Into Jazz Fusion Guitar, p.44. ISBN 0-7866-6248-4.

[Infinite-1] Juergensen, Chris (2006). The Infinite Guitar, p.50. ISBN 1-4116-9007-9.

[2] Munro, Doug (2002). Jazz Guitar: Bebop and Beyond, p.39. ISBN 978-0-7579-8281-1.

[3] Miller, Scott (2002). Mel Bay Getting Into Jazz Fusion Guitar, p.44. ISBN 0-7866-6248-4.

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