- This article is about musical harmony. For other uses of the term, see Harmony (disambiguation).
Harmony is the art of using pitch simultaneity (or chords, actual or implied) in music. It is sometimes referred to as the "vertical" aspect of music, with melody being the "horizontal" aspect. Very often, harmony is a result of several melodic lines or motifs being played at once, creating counterpoint and called polyphony.
Harmony is based on harmonics and resonances. Notes may be considered to be in harmony with each other when some of the harmonics of each note, especially the louder harmonics (which are often the lower ones), share the same frequency (with a small margin of error). Some traditions of music performance, composition, and theory have specific rules of harmony, typically amounting to a simplified description of harmonics and resonances, which will be more or less appropriate depending on the instrument(s) to which they are applied.
Although most harmony comes about as a result of two or more notes being sounded simultaneously, it is possible to create harmony with only one melodic line. There are many pieces from the baroque period for solo string instruments for example, in which chords are very rare, but which nonetheless convey a full sense of harmony.
For much of the history of western classical music, including the common practice period, the conventions and rules of harmony were strictly enforced, often by the controlling influence of the Roman Catholic Church, while folk music and non-Western music also developed often widely different notions of harmony. Church music was controlled by the churches in the Baroque and Classical periods, and music which had harmonies considered too dissonant were frowned upon. However, there was a general trend from the classical period to the 20th century in western classical music for harmony to become more advanced, with composers breaking many of the conventions which were once considered "rules".
Carl Dahlhaus (1990) distinguishes between coordinate and subordinate harmony. Subordinate harmony is the hierarchical tonality or tonal harmony well known today, while coordinate harmony is the older Medieval and Renaissance tonalité ancienne, "the term is meant to signify that sonorities are linked one after the other without giving rise to the impression of a goal-directed development. A first chord forms a "progression" with a second chord, and a second with a third. But the earlier chord progression is independent of the later one and vice versa." Coordinate harmony follows direct (adjacent) relationships rather than indirect as in subcordinate. Interval cycles create symmetrical harmonies, such as frequently in the music of Alban Berg, George Perle, Arnold Schoenberg, Béla Bartók, and Edgard Varčse's Density 21.5.
- Harmonic series
- Chord sequence
- Physics of music
- Mathematics of musical scales
- unified field
- Dahlhaus, Carl. Gjerdingen, Robert O. trans. (1990). Studies in the Origin of Harmonic Tonality, p.141. Princeton University Press. ISBN 0691091358.
- Tonal Harmony Reference Materials for the Undergraduate Theory Student
- Harmonic Progressions with demos and how to harmonise a melody
- General Principles of Harmony by Alan Belkin
- Tonalsoft Encyclopaedia of Tuning