The augmented seventh chord, or seventh augmented fifth chord,[1]orseventh sharp five chord is a seventh chord composed of a root, major third, augmented fifth, and minor seventh (1, 3, ♯5, ♭7).[2] It can be viewed as an augmented triad with a minor seventh.[3] When using popular-music symbols, it is denoted by +7, aug7,[2]or7♯5. For example, the augmented seventh chord built on A♭, written as A♭+7, has pitches A♭-C-E-G♭:
The chord can be represented by the integer notation {0, 4, 8, 10}.
The root is the only optional note in an augmented seventh chord, the fifth being required because it is raised.[4] This alteration is useful in the major mode because the raised 5th creates a leading tone to the 3rd of the tonic triad.[3] See also dominant.
Inrock parlance, the term augmented seventh chord is sometimes confusingly and erroneously used to refer to the so-called "Hendrix chord", a 7♯9 chord which contains the interval of an augmented ninth but not an augmented fifth.[5]
^Kroepel, Bob (1993). Mel Bay Creative Keyboard's Deluxe Encyclopedia of Piano Chords: A Complete Study of Chords and How to Use Them, p. 15. ISBN0-87166-579-4.
^ abGarner, Robert (2007). Mel Bay Presents Essential Music Theory for Electric Bass, p. 69. ISBN0-7866-7736-8.
^ abKostka, Stefan; Payne, Dorothy (2004). "The Dominant with a Raised 5th". Tonal Harmony with an Introduction to Twentieth-Century Music (6th ed.). New York. pp. 446–447. ISBN978-0-07-332713-6.{{cite book}}: CS1 maint: location missing publisher (link)
^Latarski, Don (1991). An Introduction to Chord Theory, p. 29. ISBN0-7692-0955-6.
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