It's called shape-note singing because the hymnal uses shape ... shapes make it easier to read and sing the music in four-part harmony. It has an archaic sound, so associated with the South ...

Certain simple ratios of vibrating string lengths produced consonance, or a pleasant-sounding combination of notes, he found ... the traditional idea that harmony can only be one way, that ...

He found a recording that isolated the track's vocals, meticulously transcribed the harmonies note for note, and then wrote some code in Processing to render it as it played. The result is ...