Music Theory Volume 1

Consonance and Dissonance

Short but wise chapter

Consonance and dissonance are subjective qualities of the sonority of intervals that vary widely in different cultures and over the ages.

Consonance (or concord) is the quality of an interval or chord that seems stable and complete in itself. Dissonance (or discord) is the opposite in that it feels incomplete and "wants to" resolve to a consonant interval. Dissonant intervals seem to clash. Consonant intervals seem to sound comfortable together. Commonly, perfect fourths, fifths, and octaves and all major and minor thirds and sixths are considered consonant. All others are dissonant to greater or lesser degree.

Context and many other aspects can affect apparent dissonance and consonance. For example, in a Debussy prelude, a major second may sound stable and consonant, while the same interval may sound dissonant in a Bach fugue. In the Common Practice era, the perfect fourth is considered dissonant when not supported by a lower third or fifth. Since the early 20th century, Arnold Schoenberg's concept of "emancipated" dissonance, in which traditionally dissonant intervals can be treated as "higher," more remote consonances, has become more widely accepted.

Dissonance is an essential element of music and used in most every culture and genre, not only for effect, but as a fundamental structural element to create motion and tension. J.S. Bach's music depends in great part on the effect of dissonance. The art of melody writing depends heavily upon the selection of consonant and dissonant tones.