Logos Seminar Series – On Modulation in Early Medieval Chant: the φθοραί in Byzantium and the vitia in the West

Presenter: Professor Charles M. Atkinson

Chair: Dr Eleanor Giraud

One of the most fascinating phenomena in early medieval chant is that of modulation: the shift from one echos to another in Byzantium and from one tonus to another in the West. In the East, a modula-tion can be produced either by parallage, a tonal shift created when the ambitus and melodic formulae of a melody move up or down within the same diatonic array, or by what are known as phthorai—corruptions—that introduce different species of octave within a given ambitus. The same phenomena are documented in the West by the 9th-century Musica and Scolica enchiriadis, the latter treating modulation under the heading of vitia—corruptions—that likewise introduce different species of oc-tave within a given ambitus. The seminar will begin with a brief paper, followed by discussion of the theoretical and practical issues manifested by examples drawn from both Eastern and Western chant.