Biyatismic chords

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Biyatismic chords are essentially tempered dyadic chords tempered by the biyatisma, 121/120.

There are two triads, nine tetrads, seven pentads and one hexad as 2.3.5.11 subgroup 11-odd-limit essentially tempered chords. In this article, voicing with the perfect fifth is prioritized.

The two biyatismic triads are in inverse relationship:

  • 1–11/8–5/3 with steps 11/8, 11/9, 6/5;
  • 1–11/8–18/11 with steps 11/8, 6/5, 11/9.

For tetrads, there are three palindromic chords and three pairs of chords in inverse relationship. The palindromic chords are

  • 1–9/8–11/8–18/11 with steps 9/8, 11/9, 6/5, 11/9;
  • 1–11/10–11/8–3/2 with steps 11/10, 5/4, 11/10, 4/3;
  • 1–3/2–18/11–11/6 with steps 3/2, 11/10, 10/9, 11/10.

The inversely related pairs of chords are

  • 1–11/8–3/2–18/11 with steps 11/8, 11/10, 11/10, 11/9, and its inverse
  • 1–11/10–3/2–11/6 with steps 11/10, 11/8, 11/9, 11/10;
  • 1–5/4–3/2–11/6 with steps 5/4, 6/5, 11/9, 11/10, and its inverse
  • 1–6/5–3/2–18/11 with steps 6/5, 5/4, 11/10, 11/9;
  • 1–11/8–3/2–5/3 with steps 11/8, 11/10, 10/9, 6/5, and its inverse
  • 1–11/10–3/2–9/5 with steps 11/10, 11/8, 6/5, 10/9.

For pentads, there are one palindromic chord and three pairs of chords in inverse relationship. The palindromic chord is

  • 1–9/8–11/8–3/2–18/11 chord with steps of 9/8, 11/9, 11/10, 11/10, 11/9.

The inversely related pairs of chords are

  • 1–11/8–3/2–5/3–11/6 with steps 11/8, 11/10, 10/9, 11/10, 11/10 and its inverse
  • 1–11/10–3/2–18/11–9/5 with steps 11/10, 11/8, 11/10, 11/10, 10/9;
  • 1–5/4–3/2–5/3–11/6 with steps 5/4, 6/5, 10/9, 11/10, 11/10 and its inverse
  • 1–6/5–3/2–18/11–11/6 with steps 6/5, 5/4, 11/10, 11/10, 10/9;
  • 1–5/4–11/8–3/2–11/6 with steps 5/4, 11/10, 11/10, 11/9, 11/10 and its inverse
  • 1–11/10–6/5–3/2–18/11 with steps 11/10, 11/10, 5/4, 11/10, 11/9.

Finally, there is a palindromic hexad,

  • 1–5/4–11/8–3/2–5/3–11/6 with steps 5/4, 11/10, 11/10, 10/9, 11/10, 11/10.

Equal temperaments with biyatismic chords include 7, 9, 15, 16, 22, 24, 29, 31, 38, 46 and 53.

See also