Chord Lab

Play it now: https://lauren.wang/chord-lab/ (Chrome or Edge, with your piano plugged in by USB)

Plug in your piano and play. Chords scroll along a treble staff toward a blue band, one per bar, on a steady beat. Play each chord as it reaches the band. The app picks every next chord for you:

• ↺ again: a chord you missed or were slow on comes back a few chords later, then less and less often as you get it right.
• ★ new: when you're doing well, a new chord unlocks (major triads → minor → more keys → inversions → diminished/augmented → 7ths).
• ≈ similar: when you're struggling, it stays close to what you just played.
• When you play the right chord, it says the name out loud ("E flat minor").
• Chord names disappear once you read a chord quickly 4 times in a row, so you're reading the notes.
• Tempo goes up every 6-chord combo and down after mistakes.

Progress is saved in the browser, so next time you start with your tricky chords.

Run it locally

Use Chrome or Edge (Safari and Firefox can't talk to MIDI pianos).

1. Connect your digital piano to the computer with USB.

2. In this folder, start a small local server:

   python3 -m http.server 8765
   

3. Open http://localhost:8765 and allow MIDI access when Chrome asks.

4. Play any note to start.

Opening index.html directly also usually works in Chrome. If the piano isn't detected that way, use the server.

No piano? The computer keyboard works too: A W S E D F T G Y H U J K play C up to C, and Z / X shift the octave.

Controls

• Wait for me (on by default): the music pauses at each chord until you play it. Turn it off to keep the beat going no matter what.
• Stop: shows a check-in with your stats, what's new, what's solid and what's still tricky. It also appears every 5 minutes.
• Settings: beat sound on/off, say chord names on/off, always show chord names, reset progress.

Files

• js/music.js: chord spelling and voicing
• js/coach.js: the levels and the next-chord picker
• js/staff.js: the scrolling SVG staff
• js/game.js: clock, judging, tempo, check-ins, saving
• js/input.js, js/keyboard.js, js/audio.js: piano input, on-screen keys, beat click