Symmetric visualization of harmony

In an effort to understand how Hooktheory organizes harmony, I’ve been working on a visualization for some time and I figured I’d share. My apologies if others find it confusing, or typos have been introduced; potentially a better version could be created.

To interpret, start with the row in the middle of the diagram; look to the left for a red box containing ‘I’. This row represents the Ionian mode of the Major scale and is what you see when you open a Hookpad.

This diagram uses Roman notation, but for the purpose of discussion, it’s best to assume the key of C(I). Chord color corresponds to type, chord extensions such a 9, 11 & 13 are included making each chord distinct.

Each row in the diagram represents a key ascending or descending in the cycle of fifths, but rather than shift notes, the C (or C#) remains the leftmost chord.

The row above C(I) is another key, to determine what it is, either:

  • Count the sharps or flats - 1 sharp
  • Use the roman notation of the red chord - V, relative to C(1)
  • Map the key color to chromatic color key - Blue is 5th note of the major scale

In this case, all signs point to the key of G, but because rows are relative to C(I), the row is displayed as C Lydian (Ly):

  • C(I), D(II), E(iii), F#(#iv), G(V), A(vi), B(vii).

The thick green border of the first chord further illustrates Lydian mode.

The key D is above G, F (Mixolydian) below C, and so on through the cycle of fifths, creating a symmetric grid that, hopefully, mirrors chord borrowing functionality in Hookpad.

Note that the keys above Lydian are what the Hooktheory team refer to as supermodes, my notation counts sharps, eg. 2#. These keys do not correspond to modes because they contain the note C#, rather than C.

Again, hopefully this visualization clarifies rather than confuses, that having all the chord relationships visible on one page is helpful, especially if you are looking for a specific chord.

Interested to hear any feedback or corrections from the Hooktheory team or others.


Since space on the page was available, another grid displays what occurs when a note in the major scale is altered.

For example, when the Aeolian/Minor mode (represented by the purple box) is altered with by sharp 7 (#7), the Harmonic Minor scale is created along with a host of other modes and chords. And so on…

Best, Sean

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What does the triangle represent here? You didn’t say in your original post.

The triangle is a symbol for major seventh quality.