Tertium minor
In
harmony, the
tertium minor is the ratio 6:5 between a pair of frequencies or, equivalently, the ratio 5:6 between a pair of wavelengths. It is the
harmonic mean of
unison and
diapente:
It is equal to diapente divided by
tertium major:
-
This means that diapente is equal to a tertium major and a tertium minor, put together.
Tertium minor 1.00110011001100110011... in binary, and it is the inversion of the major sixth (5:3), viz.
-
The major sixth is the sum of the first five reciprocals of
triangular numbers:
Tertium minor is also called the
minor third.
See also: tertium major.