ABSTRACT
This chapter presents triadic extension, linear chromaticism, and harmonic sequence. From the tenth century to the twentieth, Western harmony has ascended the harmonic series. From the open-fifth chanting of Guido’s day to full acceptance of the triad in the later Middle Ages, from the extension of the triad to include sevenths in the Baroque era to the further accretions in the nineteenth century, each addition to the vocabulary scaled the next higher rung on the overtone ladder. In art music, dominant ninth chords, like dominant seventh chords, typically behave in only one way making it possible to refer to them by function rather than by structure. As with altered dominants, inversions of ninth chords are usually not indicated in the chord symbols because the symbols become unwieldy.
