Note Trainer

Learn the fretboard with your hands, not flashcards.

A Slopsmith minigame that turns rote fretboard memorization into a game you play. It shows you the neck, asks for a note on a given string (e.g. C on the low E), and listens through the microphone to check — in real time — whether you actually played it. No clicking, no guessing: pick up the instrument and play.

It reuses Slopsmith's pitch-detection pipeline (the YIN algorithm running in a Web Worker, fed by the desktop's JUCE audio bridge, with a browser-microphone fallback), so detection is fast and works for both guitar and bass.

Why it's different

• You play, it listens. Real notes from a real instrument — not a multiple-choice quiz.
• It adapts to you. The game tracks which note/string pairs you fumble and steers practice toward your weak spots.
• It also trains your ear. A separate, mic-free mode builds relative pitch and interval recognition — the skills that actually transfer to playing music.
• It rewards progress. Combos, medals, achievements and persistent stats keep the grind feeling like a game.

Game modes

Mode	What you do
Relax	Practice with no timer — scoring, combos and stats, zero pressure.
Arcade	Beat the clock: speed bonus plus a growing combo multiplier.
Challenge	A fixed series of notes, ending in a medal (🥉/🥈/🥇) based on accuracy.
Learn	Explore mode: play a note and watch every position on the neck light up with its name and fret.
Ear training	No mic, no theory required — train your ear with note names or intervals (details below).

Ear training, in depth

A "home" reference note plays, then a mystery note; you name what you heard from on-screen buttons. This trains relative pitch — the learnable kind.

• Three difficulties: 3 notes (C E G) → the major scale (7 notes) → all 12.
• Two answer styles: by note name, or by interval — the distance from the home note (Unison, Major 3rd, Perfect 5th…). Interval recognition is the foundation of melody and chords and transfers to any key. Interval mode includes an on-screen cheat-sheet that ties each label (M3, P5, TT…) to a famous tune.
• Three tries per round: points scale down with each attempt; after the third miss the answer is revealed and play moves on.
• Adaptive practice: a per-interval mastery readout tracks how well you know each one across sessions, the picker over-samples your weak intervals, and wrong guesses get contrast feedback ("you said P4 — one semitone narrower than the answer").

Levels & focus

Four levels (data/levels.json), all unlocked from the start: Naturals, Sharps, Flats, Chromatic. Pick a level and use the mini-fretboard to choose which string(s) to drill — one string in isolation or the whole neck. Each level card shows per-string mastery stars, an overall mastery bar, your best score, and the best medal you've earned.

• Free practice ignores level constraints and just uses the controls above.
• 🎯 Drill weak spots appears once you have practice data: it auto-focuses a relax session on the exact note/string pairs you miss most (the engine's pcs allowlist narrows the target pool to your trouble zone).

Progress — best scores, medals, per-note/string mastery, picked strings, lifetime totals and achievements — is saved on the backend. The microphone choice lives in localStorage.

Gamification

• Combos build a score multiplier (1× → 2× at a 3 streak → 3× at 6). The success chime climbs in pitch and gains a sparkle as the streak heats up, and the combo counter glows (hot → blazing).
• Achievements are long-term goals — first medal, 10-combo, mastering a string, 100/500 lifetime notes — that unlock with a toast and live in the header.
• Medals are awarded per level/tier for hitting the accuracy threshold.

How checking works

The audio gives us the frequency, not which string was plucked. A note counts as correct when its pitch class matches the target and the frequency falls within the physical range of the indicated string (any octave of that note on that string is valid). "Right note, wrong string" and "wrong note" get distinct feedback; after a few failed attempts the game reveals the correct positions on the fretboard.

Structure

plugin.json     manifest (menu entry, screen, script, routes)
routes.py       serves utils/workers, config (progress), tunings, levels
screen.html     layout: setup, HUD, fretboard SVG, results
screen.js       orchestrator: state, audio lifecycle, game loop
utils/
  audio.js          microphone capture + YIN          (window._noteTrainerAudio)
  note-math.js      note/frequency/fretboard math      (window._noteTrainerMath)
  fretboard.js      SVG fretboard rendering            (window._noteTrainerFretboard)
  game.js           game engine: targets, validation, scoring (window._noteTrainerGame)
  ear.js            ear-training engine: rounds, judging, scoring (window._noteTrainerEar)
  achievements.js   long-term achievement evaluator    (window._noteTrainerAchievements)
  ui.js             HUD, feedback, sounds (note synth), results, toasts (window._noteTrainerUI)
workers/yin.js  pitch detection (Web Worker)
data/levels.json  level curriculum

Tests

npm run test:js      # node --test  (note-math, game, ear, achievements, yin)
python -m pytest     # backend (config, serving, tunings, levels)

The Python tests require pip install -r requirements-test.txt (fastapi, httpx, pytest). Audio/mic behaviour can't be unit-tested — verify it live by running Slopsmith and opening the plugin screen.