Salamander Grand Piano — Alexander Holm
Source: https://github.com/Tonejs/audio/tree/master/salamander
Original distribution license: Creative Commons Attribution 3.0 Unported
https://creativecommons.org/licenses/by/3.0/
Upstream README: https://github.com/Tonejs/audio/blob/master/salamander/README
Solfaapp uses an unmodified subset of the MP3 samples, pitch-shifted at playback.