The musical interval we call a perfect fifth is the second most fundamental one (the most fundamental being the unison or octave). In western music, we have ended up with twelve pitches, all related to one another by the interval of the perfect fifth (more or less). On a piano keyboard, these are arranged in order by frequency. I decided instead to try arranging them so that adjacent pitches were a perfect fifth apart; this arrangement is known to musicians as the circle of fifths . Then, I applied the color wheel to this circle, so that pitches which were closely related by perfect fifths would be close in color:
This turned out to be useful for showing things about tonality. For example, all the notes in a major scale are grouped together:
This means that if you're playing a piece that stays in one key, it stays in one area of the circle. If the key changes, the notes are in a new area. Also, notes which are not in the key stand out.
This same coloring can be applied to the scrolling score. Here are the first four bars of Chopin's Prelude, Opus 28, No. 3 in G major, rendered in Music Animation Machine notation using harmonic coloring:
This excerpt remains entirely in a single tonal area, that of the tonic. In the following excerpt, the music modulates chromatically, ending with a V-to-I cadence (violet-to-blue in the bass line):
This video (Brahms Capriccio, opus 76 no. 2) uses Harmonic Coloring