ABSTRACT
Conventional tonal theory places structural emphasis on tritone symmetries and eleven-pitch-class harmonic areas and, in so doing, uncovers common compositional approaches to specific chromatic relationships of seemingly divergent musical epochs. The term "eleven-pitch-class tonality" relates directly to the first of these concepts, that of the missing pitch. The very fact that eleven-pitch-class systems comprise tritones organized around minor third cycles naturally raises chromatic pitch classes that are inflections of diatonic ones belonging to the key. The chapter proposes that tonality, along with its hierarchal structure, and its division into 24 major and minor keys, is ultimately derived from a chromatic gamut of all available pitch classes that is partitioned into diatonic scales of differing whole- and half-step patterns. The major advantage of perceiving any given key as a reordered hexachord is that its reordering in fifths provides the harmonic relationships that characterize the large-scale harmonic plans of most eighteenth-century music.
