Instrument samples: tonejs-instruments by Nicholai Brosowsky.
https://github.com/nbrosowsky/tonejs-instruments
Samples licensed under Creative Commons Attribution 3.0 Unported:
https://creativecommons.org/licenses/by/3.0/
Upstream revision: 622c2f1c32c8cfce4158ddc3eb26e518ddef37e5
Acoustic guitar source: University of Iowa Electronic Music Studios.
Piano source: VSO2, as credited by upstream sample-source-info.txt.
MP3 files redistributed unchanged. Playback may transpose nearby samples and apply gain/release envelopes.