Cartonic

Absolute-pitch identification trainer: it plays a note, you name it, and your misses accumulate into a map of how you hear.

Problem: An accuracy percentage tells you how often you miss, not how you miss.
The misses carry the information: which notes you confuse, in which direction, how fast, and whether that changes over time.
Approach: A Tone.js synth plays a pitch; you tap the note you think it was. Nothing you do is ever recorded through a microphone.
The twelve pitch classes sit on a logarithmic spiral; each node's halo scales with your accuracy on that note, and a thread is drawn between any pair you confuse often enough.
A 12×12 confusion matrix is the base.
Tips are generated from those detectors once you have 15 trials, and they typically quote the specific note and figure that triggered them.
Outcome: Everything is a single triangle-wave synth, so the ear you are training is an ear for one timbre.
The app never hears you, so it says nothing about whether you can produce a pitch, only whether you can name one.
The citations are the framing behind the detectors, not evidence that the app works.

Try it — this is the real thing

ReactTypeScriptTone.jsD3

Rigorously