Island chords

An island chord is an 15-odd-limit essentially tempered dyadic chord which is tempered by 676/675 (island comma).

The island tetrad under octave reduction consists of three 15/13 intervals followed by a 13/10, which closes on the octave since the island comma, 676/675, is tempered out; in other words an island tempered version of

• 1-15/13-4/3-20/13, with steps 15/13-15/13-15/13-13/10.

Contained within it are a barbados triad,

• 1-13/10-3/2, with steps 13/10-15/13-4/3,

its inversion,

• 1-15/13-3/2, with steps 15/13-13/10-4/3,

and an island triad,

• 1-15/13-4/3, with steps 15/13-15/13-3/2,

which in another position is the 1-3/2-26/15 chord.

Another island tetrad of interest is a 26/15 over a major triad,

• 1-5/4-3/2-26/15, with steps 5/4-6/5-15/13-15/13,

and its inversion,

• 1-6/5-3/2-26/15, with steps 6/5-5/4-15/13-15/13.

See also

• Arto and Tendo Theory
• The Archipelago