How it works
The question comes before the chord
The usual question is «which chord can follow this one?», and it has thousands of answers. This tool asks another one first: what is the listener expecting at this moment, and what do you want to do with that? There are only three answers — confirm, delay, surprise — and once you have chosen one, the chords that do it can be counted.
A surprise needs a handrail
After G7, everybody expects Cmaj7. A♭maj7 instead sounds like «it arrived, but somewhere else» — not like a mistake — because the B of G7 still rises to C, exactly as it would have. That surviving thread is a handrail: a note that stays, a note that moves a semitone to where it was going, a bass that keeps walking. In the surprise panel you choose which ones must survive, and the tool returns every chord that keeps all of them.
What the numbers mean
st means semitones. The distance is how far the notes have to move, in total, to get from one chord to the other: near 0–2, mid 3–4, far 5–6, very far 7 or more. Each chord shows two degrees: in the key (I, ♭VI…) and counted from the chord you are on, which is how the book's maps and cards are written.
The list is not a ranking
The candidates come nearest first, and that order means nothing about quality. The engine narrows three hundred chords down to a handful; which one is right is decided by playing them. If nothing comes out, loosen one condition. If too much comes out, add one. The numbers filter. The ear decides.
What it does not calculate
Rhythm, register, texture, timbre and style. The engine sees the notes of each chord and its bass; the way the voices are spread when you press play is chosen here to move as little as possible, so you can hear the note that delivers. On your instrument, you decide the voicing.
On an iPhone, turn the silent switch off: it mutes web audio.
Project 05 · Harmony
Project 03 · Harmony
Project 06 · Perception and creativity
