Consonance and dissonance: Fundamentals of music, Music is composed of phenomena of sound, and “music theory” considers how those phenomena are and can be used in music. Music theory includes considerations of mel-ody, rhythm, counterpoint, har-mony, and form; tonal systems, scales, tuning, intervals, consonance, dissonance, durational proportions, and the acoustics of pitch systems; composition, performance, orchestration, ornamentation, improvisation, and electronic sound production; etc.
Table of Contents
Consonance and dissonance | Rhythm | Chord | Melody | Harmony | Fundamentals of music | Music theory
Consonance and dissonance:
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 Cho-rd which 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 to be consonant. All others are dissonant to a greater or lesser degree.
However, 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 is used in almost 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.
Rhythm:
Rhythm is produced by the sequential arrangement of sounds and silences in time. Meter measures music in regular pulse groupings, called measures or bars. The time signature or meter signature specifies how many beats are in a measure, and which value of the written note is counted or felt as a single beat.
Through increased stress or variations in duration or articulation, particular tones may be accepted. There are conventions in most musical traditions for the regular and hierarchical accentuation of beats to reinforce a given meter. Syncopated rhythms contradict those conventions by accenting unexpected parts of the beat. Playing simultaneous rhythms in more than one-time signature is called polymeter. See also polyrhythm.
In recent years, rhythm and meter have become an important area of research among music scholars. Recent work in these areas includes books by Bengt-Olov Palmqvist, Fred Lerdahl and Ray Jackendoff, and Jonathan Kramer.
Chord:
A Cho-rd is a group of tones heard or conceived as sounding simultaneous. In some instances, tones of a Cho-rd not sounding simultaneously but successively, for example in an arpeggio, in a compound me-lody, or the style brisé, may still be considered to form a Cho-rd. There is an ongoing debate about the minimum number of tones required to constitute a Cho-rd: two, or three (see Cho-rd). The exploitation of Cho-rds and their patterns of succession or progression is a prominent feature of Western music
but is also found in other cultures. The study of Cho-rds is a primary concern of music theory for many reasons, but especially their significance in, and effect upon har-mony, counterpoint, form, and tension and release.
In common-practice har-mony, Cho-rds are often formed of three tones in stacked thirds; such three-tone Cho-rds are called triads. They consist of a primary tone called the root, a second tone a third above the root, and another tone a third above that (that is, a fifth above the root). Triads take the name of their root tone (e.g. C, F, or E) and are further described by the quality of the intervals between their tones (e.g. A major, C minor, E diminished). Cho-rds may be inverted by changing the vertical arrangement of tones,
extended by adding tones that in the common definition of consonance and dissonance necessarily are dissonant, or altered by modifying one or several of their tones usually by a chromatic semitone. Seventh Cho-rds consist of a triad plus an additional tone a third above the fifth, i.e. a major seventh (in the case of major triads), minor seventh (in the case of diminished, minor, or major triads), or diminished seventh (only in the case of diminished triads) above the root. Clusters are built by vertical arrangements of adjacent tones.
Melody:
A me-lody is a series of tones sounding in succession that typically move toward a climax of tension and then resolve to a state of rest. Because me-lody is such a prominent aspect in so much music, its construction and other qualities are a primary interest of music theory.
The basic elements of me-lody are pitch, duration, rhythm, and tempo. The tones of a me-lody are usually drawn from pitch systems such as scales or modes. Mel-ody may consist, to an increasing degree, of the figure, motive, semiphrase, antecedent and consequent phrase, and period or sentence. The period may be considered the complete mel-ody, however, some examples combine two periods, or use other combinations of constituents to create larger form melodies.
Harmony:
Har-mony is the study of vertical sonorities in music. Vertical sonority is produced by the relationships of pitches that occur together; usually, this means at the same time, although har-mony can also be implied by a mel-ody that outlines a harmonic structure. How tones sound together and in succession to create what we recognize as music is a principal concern in music theory.
In Western music of the Common Practice Era, harmonies are generally tertian. This means that the intervals of which the Cho-rds are composed are a third—not that the Cho-rd is necessarily a triad (composed of three notes). Quartal and quintal har-mony are built on the interval of a fourth and fifth, respectively. In tertian har-mony, a root position triad (with the root note in the lowest voice) consists of the root note, a note a third above, and a note a third above that (a fifth above the root).
Seventh Cho-rds add a fourth note, a third above the top note of a triad (a seventh above the root). In 20th century classical music and jazz, many alternative types of har-mony are explored: modal, quartal, etc. One way to analyze har-mony is through a Roman numeral system whereby Roman numerals are used to identify Cho-rds based on their scalar roots (I through VII). in popular music and jazz, a system of Cho-rd symbols is commonly used (Cmaj7, E9, etc.). post-tonal music employs a variety of approaches, most frequently set theory.
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