Organum for Mary Beth Ackerley -- notes

Hello, there, everyone, and here are the notes that I wrote about
_Organum for Mary Beth Ackerley_ in 13-tET:

Organum for Mary Beth Ackerley (13-tET, MBA Phi Voice) ~2:25

In the era of around 850-900, certain treatises from medieval Europe
document a new art of organum or "organized" part-singing, and
describe for singers how it is done. By the 12th century, composed
organa take a Gregorian chant and often draw out each note to a kind
of a moveable pedal point, with a florid melody woven above and about
it. This piece, using a timbre named in Mary Beth Ackerley's honor and
optimized for the 13-tET "fifthlike" interval or 8-step and its
near-Phi interval or 9-step, is inspired by such styles, along with an
"organ" timbre based on FM Algorithm 32 of the TX-802 (with a
"drawbar-like" mix of partials).

Here I might add that the 9-step interval of 13-tET at ~830.77 cents,
is quite close to the Golden Section or Phi at ~833.09 cents, and even
closer to the ratio 13:21 (~830.25 cents) formed from two of the
numbers in the famous Fibonacci series (1 1 2 3 5 8 13 21 34 55...)
where successive pairs form ratios more and more closely approximating
Phi.

In neo-Gothic tuning systems of a more conventional kind, this
interval typically serves as a "supraminor sixth" or augmented fifth,
a highly valued effect; but in 13-tET, which has its own categories,
such conventional names may or may not fit the "harmonic geometry" of
a beautiful and different system.

Often the 9-step is more or less equivalent in its "quasi-diatonic"
role to a usual minor sixth, the intervals "adding up" in their own
way.

Again, thanks to Mary, Robert, and everyone for your encouragement and
support as we share our music together.

In peace and love,

Margo