Harmony (music)

III

History

Harmony first appeared in Western music in the Middle Ages as composers began to add contrapuntal parts to plainchant, which had developed as a monophonic (unharmonized single-part) music. Over the centuries composers explored different combinations of intervals and different ways of connecting them. Harmonies evolved from more or less coincidental occurrences between contrapuntal lines, with stable intervals occurring only at beginnings or endings of sections. Eventually, composers began to regulate carefully the interactions of consonances and dissonances. At first only fourths, fifths, and octaves were considered consonant; later, thirds and sixths were added to this category.

A

Functional Harmony: Growth and Dissolution

By the 16th century, in the music of such composers as the Italian Giovanni da Palestrina and the Flemish Orlando di Lasso, the triad had become the preferred sonority. In music of this era the motion from one triad to another is so arranged in the parts that a complete triad (with root, third, and fifth present) is sounding almost all the time. Functional harmonic motion appears at many cadences. Within phrases, however, the use of modes (scales other than major and minor) prevents the sense of directed harmonic motion that is found in later eras throughout phrases of tonal music. By the second half of the 17th century, functional harmony had become the established musical language. This is the language in which composers such as the Germans Johann Sebastian Bach and Ludwig van Beethoven, the German-English George Frideric Handel, and the Austrians Joseph Haydn and Wolfgang Amadeus Mozart wrote their music.

By the 19th century functional harmonic progressions had been in use so long that composers considered them too commonplace for many of their individual needs. Within functional harmony, composers such as the Polish-French Frédéric Chopin and the Germans Robert Schumann, Johannes Brahms, and Richard Wagner explored new sounds. Their techniques included connecting chords hitherto considered only distantly related to one another; adding nonharmonic tones that last for most of the duration of a chord; employing dissonant chords more often than triads; using chromatic notes ever more frequently; and moving rapidly from one key to another without firmly establishing any one of the keys passed through. Novel harmonic effects became a primary interest.

B

20th-Century Replacements

As a result of these 19th-century trends, functional harmony had ceased to be a potent force in new music by the early 20th century. Some composers, such as the Frenchman Claude Debussy, the Hungarian Béla Bartók, and the Russian-born Igor Stravinsky, continued to write music based on a tonal center. These composers, however, projected the sense of a tonic by means other than functional tonality. Such techniques included frequently repeating the tonic note; centering melodies around it; and employing an ostinato (a repeating pattern) that featured the tonic.

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Other composers, such as the Austrians Arnold Schoenberg, Alban Berg, and Anton Webern, abandoned a sense of tonality altogether and began writing atonal music (that is, music without a tonic; see Atonality). In this music the earlier distinction between consonance and dissonance no longer holds, because, depending on the context, all chords and intervals have the potential to sound either stable or in need of resolution. The term harmony can still be used to describe a group of notes sounded together in this music. The triads and other chords that are common in tonal music, however, hold no special status—they are simply various three- or four-note chords among many others. No harmonic progressions exist that are common to many pieces; instead, in each piece an individual harmonic language is developed. In recent writings the term simultaneity has replaced harmony to describe notes that sound together in this music.

IV

Categories and Names of Tonal Chords

The first and second sections of this article discussed the essential qualities and history of the traditional harmonic system of Western music. This final section is a summary of technical information about chords and their nomenclature.

The most common chords in tonal music are triads and seventh chords. Triads, as previously discussed, appear in four principal varieties: major, minor, diminished, and augmented. Seventh chords have five principal varieties:

A

Functional Chord Names

Functional names show the placement of a given chord in a major or minor key. Such names include the Roman numerals used for chords, as well as the following terms:

Whether any of these chords is major or minor depends on its position in the key. For a major key the chord types are as follows:

For a minor key (built on a harmonic minor scale, such as A B C D E F G# A) the chord types are as follows:

In one common system major chords are indicated by capital Roman numerals (I, IV) and minor chords by lowercase Roman numerals (ii, vi); diminished chords are written in lowercase, followed by the symbol ^o (for example, ii^o) and augmented chords are shown in capitals, followed by the symbol ⁺ (for example, III⁺).

In a tonicization, the chromatic chord is shown either in parentheses or before a slash, followed by the Roman numeral for the note that has lent its key; an example is (V₇)V or V₇/V, read as “five-seven of five.”

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