Chords are stacked distances

Two distances, glued together

A triad is not three notes to memorise — it is two intervals stacked: a 4-semitone band and a 3-semitone band. Stack them 4 + 3 and the chord is major; flip to 3 + 4 and it is minor — watch the middle note slide one semitone and listen to the light change. Slide the root anywhere: the stack is rigid, so the chord quality travels with it.

Tap any key to put the root there. Switch quality and watch one note slide; switch inversion and watch a note hop up an octave.

What to try

Major → minor in one move. Play C major, then tap Minor. Only the middle note moved — down one semitone — and the whole colour darkened. Every major/minor pair differs by exactly that one semitone of stacking.

Inversions are rotations. Tap 1st inversion: the root hops up an octave and the stack re-reads as 3 + 5 from the new bottom note — but the letter names have not changed. Same three notes, different floor.

Symmetry sounds strange. Diminished (3+3) and augmented (4+4) stack the same distance twice. Equal stacks have no “home” orientation — which is exactly why both sound unstable.

Continue in the course

This explorer pairs with the Chords section of the Essentials path, where the ideas are built up step by step — or head back to all explorers.