Sub-harmonics are lower frequencies whose harmonic series also contain all given components.

Evidence

This is the case because by definition, 100 divides into each harmonic frequency to give an integer result (n) and all values appearing in the 100 Hz row are found by integer (m) division of 100 Hz; therefore all values in the 100 Hz row can be gained by division of harmonic frequencies by (m  n), which must itself be an integer. These are f0 values (50 Hz, 33 Hz, 25 Hz, 20 Hz, etc.) whose harmonic series also contain all the given components, and they are known as “sub-harmonics.” This is why it is the highest common factor which is used. — David Howard, Jamie Angus, coustics and Psychoacoustics, 844

Categorization

• DEFINE: Defines ‘sub-harmonics’ in terms of the highest common factor of harmonic frequencies.