The word "diatonic" = "dia" (through) + "tonic" (tones), or literally "through the tones." In a certain sense, "diatonic pitches" can be thought of as the "normative" pitches of a scale, and "chromatic" pitches ("chromos" = color) are those pitches that give additional color to the scale. In traditional Western music, the "White-Key Modes" are the most normative, and so it is no surprise that "diatonic" is usually used to refer to Major Scales and their modal rotations.
I prefer "diatonic" to refer to scales containing only whole-steps and half-steps, without consecutive half-steps. To me, these scales sound "the least chromatic" and, as you see, I am now using the word "diatonic" to mean "not chromatic." If we allow "diatonic" to refer to any contextually normative scale at all, then the leading-tone in Harmonic Minor is diatonic, as are pentatonic, hexatonic, and whole-tone scales, and the various other 7-tone scales that contain augmented seconds, and even the "Heptatonia Tertia" Modes (five whole-steps, then two half-steps) would be called "diatonic." Indeed, in 12-tone serial music, the chromatic scale itself would have to be taken as the "diatonic" norm of that music's sound world. Nevertheless, I think we should draw a line somewhere earlier than that, so as to prevent "diatonic" from becoming totally meaningless.
Jody Nagel
June 19, 2010
Copyright © 2010 by Jody Nagel. All rights reserved. Call 1-765-759-1013 or Email for additional information.