The Four Genera of Byzantine Scales

A note about microtonal notation

There is no consensus on a microtonal notation for Byzantine music. For all practical purposes, each whole-step in Byzantine music is broken up into sixths (whereas in Western music, it is divided into halves). Therefore I've taken the liberty of setting up the following standard in my own music:

In 1881, the Patriarchate of Constantinople convoked a commission to come to a standard definition of the four main genera of musical scales used for Byzantine liturgical purposes: The Diatonic, the Enharmonic, and the two Chromatic: Soft and Intense (sometimes known as “Hard Chromatic”). The Patriarchal Commission decided that the octave should be broken up into 72 degrees; hence, a Western equal-tempered half-step would equal 6 degrees. The four genera were then defined with the following intervals:

The Diatonic Genus

In this genus, βου and ζω are lowered by one-third of a half-step, relative to an even-tempered intonation.

The Enharmonic Genus

This genus is equivalent to an even-tempered intonation.

The Soft Chromatic Genus

In this genus, we lower βου and ζω by one-third of a half-step, and we lower πα and κε by two-thirds of a half-step, relative to an even-tempered intonation.

The Intense Chromatic Genus

In this genus, we lower βου and ζω by exactly one half-step, and we raise γα and high νη by two-thirds of a half-step.