III.

Nondiatonic Scales

By the late 19th century, because of the ever-increasing use of sharped and flatted tones, Western music was based not on diatonic scales, but on a chromatic scale: 12 tones within the octave, all a half-step apart—C C-sharp D D-sharp E F F-sharp G G-sharp A A-sharp B (C). Many composers have experimented with other scales, such as the whole-tone scale—C D E F-sharp G-sharp A-sharp (C)—and microtonal scales (using intervals smaller than a half step). Pentatonic, or five-tone, scales, found in much folk and non-Western music, normally mix step-and-a-half intervals (D-F, E-G, A-C, etc.) with whole steps: C D F G A (C) or C D E G A (C). Many other scales exist, including the heptatonic (seven-tone) scales with half-steps.