What problem does it solve?
The biggest frustration for harmonica beginners: “I’m playing a note — but is it the right one?” HarpMaster gives you instant feedback every time you blow or draw. What note did you play? Which hole is it? Is it in tune? All visible at a glance.
Core capabilities
- Real-time pitch detection — microphone capture + YIN algorithm, < 30 ms latency
- Interactive harmonica view — highlights the active hole with color-coded action (blow / draw / bend / overblow)
- Cent-precision tuning indicator — tells you exactly how flat or sharp
- 21 keys supported — Low C through High G, covering every common harmonica
- 25+ tuning systems — diatonic (Richter, Country, Paddy Richter, and more) plus chromatic (Solo / C6 / Richter across 8/10/12/14/16-hole variants)
- Adjustable A4 reference — 438–445 Hz to match your ensemble’s tuning
How it works
The core uses the industry-standard YIN pitch detection algorithm, running as WebAssembly (aubio yinfast) with automatic fallback to a pure JS implementation for compatibility. Samples at 44.1 kHz, FFT size 2048, with a confidence threshold of 0.7 to filter out noise.
iOS microphones tend to be quieter, so we add RMS normalization and automatic gain compensation — quiet playing still detects reliably.
Why this design
All audio processing stays on your device — no recording ever leaves your phone. Detection results are throttled to 30 ms (~33 fps) to keep the 60 fps UI smooth. A hole-matching engine sits between raw pitch and visual feedback, mapping notes onto the harmonica based on your current key + position + tuning settings — so even non-C harmonicas map correctly.