Enharmonic Genus - Notation

Notation

Modern notation for enharmonic notes requires two special symbols for raised and lowered quarter tones or half-semitones or quarter steps. Some symbols used for a quarter-tone flat are a flat with either an upward-pointing arrow or an acute accent above it, or a simple grave accent or downward-pointing arrow ↓. For a quarter-tone sharp, some symbols are h (half sharp), a sharp with either a downward-pointing arrow or a grave accent above it, or a simple acute accent or upward-pointing arrow ↑. Three-quarter flat and sharp symbols are formed similarly. Other symbols are a struck-through or crossed flat (♭ or ), or a backward flat for quarter flats, and ‡ or for quarter sharp. Hence modern notation for an enharmonic tetrachord would be:

D E♭♭ F G ,

or

A B♭♭ C D .

The double-flat symbol is preferred for modern notation of the third tone in the tetrachord to keep scale notes in letter sequence, and to remind the reader that the third tone in an enharmonic tetrachord (say F, shown above) was not tuned quite the same as the second note in a diatonic or chromatic scale (the E♭ expected instead of F).

Like the diatonic scale, the ancient Greek enharmonic scale also had seven notes to the octave (assuming alternating conjunct and disjunct tetrachords), not 24 as one might imagine by analogy to the modern chromatic scale. A scale generated from two disjunct enharmonic tetrachords is:

D E♭♭ F G - A B♭♭ C D or, in music notation starting on E: Play,

with the corresponding conjunct tetrachords forming

A B♭♭ C D E♭♭ F G or, transposed to E like the previous example: Play.

Ancient Greek notation, transferred to modern notation might be more analogous to:

D D D♯ G - A A A♯ D