We counted trichords in a database of vocal polyphony. In modern terminology, the most common in the thirteenth to sixteenth centuries were major (in semitones: 047), minor (037), suspended (027), unnamed (025, 035), and diminished (036). Prevalence profiles correlated with predictions of simple models of roughness and harmonicity; sometimes also with evenness (pitch-class spacing), but not diatonicity. From the thirteenth to the fifteenth century, 047 and 037 became more relatively prevalent, after which profiles stabilized. Our results imply that today the C/D of trichords depends mainly on familiarity, roughness, and harmonicity. C/D is best understood in an interdisciplinary, psychohistoric approach.

No abstract