Diatonic Harmony


According to the Oxford Dictionary of Music Harmony is:

At its simplest, the simultaneous sounding of 2 or more notes**; in this sense synonymous with chord. More broadly, however, harmony refers to organization and arrangement of chords and their relationships to one another. It therefore concerns not only music’s vertical, synchronic dimension, but also its horizontal, diachronic progress. Used in this sense, short passages, complete works, a comp.’s oeuvre, or entire periods or genres of music may be described or characterized in terms of their harmony.

“harmony.” In The Oxford Dictionary of Music, edited by Kennedy, Joyce, Michael Kennedy, and Tim Rutherford-Johnson. : Oxford University Press, 2012.

**Note we have defined a chord (see below) as having three or more notes. This is to disambiguate it from “dyad” or “interval.” However, there are instances of harmonies that only have two chords (i.e. a power chord). Some would argue that a power chord would imply a third omitted note (a “ghost”).

Some Useful Terms:

  • Diatonic vs. Chromatic
    • Diatonic harmony: chords within the key (includes all possibilities in a minor key)
    • Chromatic harmony: chords outside of the key
    • Note that the term “diatonic” can also refer to a family of scales that contain the major, natural minor, and modes.
  • Chord: Combination of 3 or more pitches (*pitch classes, specifically) played simultaneously 
  • Tertial (vs. Quartal or Quintal):
    • Tertial harmony: Harmonies based on thirds (basis for most Western music: triads, sevenths, ninths, elevenths, etc.) 
    • Quartal harmony: Harmonies based on fourths (i.e. a chord made of C-F-Bb-Eb)
    • Quintal harmony: Harmonies based on fifths (i.e. a chord made of C-G-D-A)