Pitch Fox — original lesson diagrams, scripts and generated exercise examples
Authored/reorganized 2026-10-04. Voice synthesis: Kokoro v1.0, af_heart.

Piano: Salamander Grand Piano by Alexander Holm. CC BY 3.0 Unported.
https://github.com/sfzinstruments/SalamanderGrandPiano
MP3 distribution: https://tonejs.github.io/audio/salamander/
https://creativecommons.org/licenses/by/3.0/

Guitar: samples edited by Nicholaus P. Brosowsky, tonejs-instruments,
from University of Iowa Musical Instrument Samples. CC BY 3.0 Unported
for tonejs-instruments edited samples.
https://github.com/nbrosowsky/tonejs-instruments
http://theremin.music.uiowa.edu/
https://creativecommons.org/licenses/by/3.0/

Violin: samples edited by Nicholaus P. Brosowsky, tonejs-instruments,
from CC0 VSCO 2 Community Edition (Sam Gossner, Simon Dalzell; cutting by
Elan Hickler/Soundemote). CC BY 3.0 Unported for edited samples.
https://github.com/nbrosowsky/tonejs-instruments
https://github.com/sgossner/VSCO-2-CE
https://creativecommons.org/licenses/by/3.0/

Instrument changes: compressed to MP3; repitched, mixed, converted to mono,
volume/duration shaped and re-encoded into original narrated exercises.
No endorsement by sample authors is implied.

Kokoro model/voice pack: hexgrad/Kokoro-82M, Apache-2.0.
https://huggingface.co/hexgrad/Kokoro-82M
https://huggingface.co/hexgrad/Kokoro-82M/blob/main/VOICES.md
https://www.apache.org/licenses/LICENSE-2.0
Local inference wrapper: kokoro-onnx, MIT (thewh1teagle).
https://github.com/thewh1teagle/kokoro-onnx
Models/runtimes are not distributed with these clips or the mobile app.