The antonym to consonance, hence a discordant sounding together of two or more notes perceived as having ‘roughness’ or ‘tonal tension’. In Pythagorean terms this meant that dissonances were intervals produced by string lengths in ratios formed from numbers greater than 4. For the subsequent development of this view by music theorists and for psychoacoustic explanations of the phenomenon of consonance and dissonance, see Consonance.
See also Fourth, Resolution and Septimal system.