Coco Ear Training – a research-backed ear training app for musicians

Hey HN, I'm Marco, a musician and developer. I built Coco because every ear training app I tried felt like a random quiz generator with no actual pedagogy behind it.

*What it is:* A mobile app (iOS/Android) with structured courses for ear training (intervals, chords, scales, relative pitch, and pitch recognition). Sessions are 2–5 minutes. Levels unlock sequentially, each one designed with a specific learning goal.

*How I got here:* I spent a long time going through the research literature on pitch perception and aural skill acquisition (Levitin, Zatorre, Deutsch, and others). A few findings shaped the whole design: 1. Isolated interval drills barely transfer to real musical listening. Tonal context matters. 2. You learn faster when you start with maximally contrasting sounds and gradually introduce similar ones ("contrast before similarity"). 3. Short daily sessions with spaced repetition outperform long sporadic ones. 4. Most people conflate ear training with perfect pitch. Relative pitch (understanding how notes relate in context) is the actually useful skill.

No existing app I found followed these principles in a structured way. Most just randomize exercises from a flat pool with no progression logic. So I built one.

*What's different pedagogically:* Every course follows a deliberate arc. For example, in melodic intervals you don't start with all 12 intervals at once; you start with a perfect 5th vs. minor 2nd (maximally different), build up contrast pairs, then progressively add intervals that are closer in size. Each practice level is preceded by a short theory intro so you know what you're listening for and why.

*Current state:* Just launched. Six courses live (Perfect Pitch, Relative Pitch, Melodic Intervals, Harmonic Intervals, Chords, Scales). It's still early and I'm actively iterating. Would love feedback from anyone here who plays music or has thought about how skill acquisition works in audio/perceptual domains.

Happy to answer questions about the pedagogical design, the technical architecture, or the research that informed it.