Shape Note

???? visualize playing music directly on the staff
???? or tap on the staff to hear what lines or spaces sound like
⬡ comes with a neat neo-Riemannian visualization
♬ and ear training exercises.

Thanks to ദിവ്യ for the colors, William Little and William Smith for the shapes, and Πυθαγόρας ὁ Σάμιος, 朱載堉, Guido D'Arezzo and Leonhard Euler for basically everything else.