Classical music as resulting from the addition of a ninth below a (dominant) seventh chord |175x175pxIn the 18th century, ninth and eleventh chords were theorized as downward extensions of
seventh chords, according to theories of supposition. In 1722,
Jean-Philippe Rameau first proposed the concept that ninth and eleventh chords are built from seventh chords by (the composer) placing a "supposed" bass one or two thirds below the
fundamental bass or actual root of the chord. With the theoretical chord F–A–C–E–G–B the fundamental bass would be considered C, while the supposed bass would be F. The theory of supposition was adopted and modified by
Pierre-Joseph Roussier,
Friedrich Wilhelm Marpurg, and other theorists.
A. F. C. Kollmann, following
Johann Kirnberger, adopted a simpler approach and one closer to that prevalent today, in which Rameau's "supposed" bass is considered the fundamental and the ninth and eleventh are regarded as transient notes inessential to the structure of the chord.'s
Ossa arida (1879), in, "a striking anticipation of twentieth-century harmonic experimentation". |175x175pxIn 19th century, the
seventh chord was generally the upper limit in "chordal
consonance", with ninth and eleventh chords being used for "extra power" but invariably with one or more notes treated as
appoggiaturas. in thirds: C–E–G–B–D–F–A–C. |175x175px In the 20th century, especially in
jazz and
popular music, ninth chords were used as elaborations of simpler chords, particularly as substitutes for the tonic triad at the end of a piece.
Jazz and funk Jazz from the 1930s onward,
jazz fusion from the 1970s onward and
funk all have been seen to use extended chords as a key part of their sound. In these genres, chords often include added ninths, elevenths and thirteenths as well as their altered variations. In jazz and jazz fusion, compositions consist of complex
chord progressions in which many of the chords are extended chords and in which many of the
dominant seventh chords are
altered extended chords (e.g., A7add911 or D7911). Funk also uses altered extended chords, but in this genre, pieces are usually based on a vamp on a single chord, because rhythm and
groove are the key elements of the style. When extended chords are voiced in jazz or jazz fusion, the root and fifth are often omitted from the
chord voicing, because the root is played by the bass player. ==Chord structure==