Post-tonal music theory is the set of theories put forward to describe music written outside of, or 'after', the tonal system of the common practice period. It revolves around the idea of 'emancipating dissonance', that is, freeing the structure of music from the familiar harmonic patterns that are derived from natural overtones. As music becomes more complex, dissonance becomes indistinguishable from consonance.
In the latter part of the 19th century, composers began to move away from the tonal system. This is typified in Richard Wagner's music, especially Tristan und Isolde (the Tristan chord, for example). Arnold Schoenberg and his pupil Anton Webern proposed a theory on the emancipation of the dissonance to help analyse the general trend and, in particular, their own atonal music. Composers such as Charles Ives, [1] Dane Rudhyar, [2] and even Duke Ellington [3] and Lou Harrison, [4] connected the emancipation of the dissonance with the emancipation of society and humanity.
The basic idea is that as time progresses, the ear becomes acclimatised to more and more complex sounds. This happens not just for individuals but also for societies as they start to write more complex music. Consonance and dissonance become indistinct from each other: dissonances slowly become heard as consonances. Jim Samson [5] explained it this way: "As the ear becomes acclimatized to a sonority within a particular context, the sonority will gradually become 'emancipated' from that context and seek a new one. The emancipation of the dominant-quality dissonances has followed this pattern, with the dominant seventh developing in status from a contrapuntal note in the sixteenth century to a quasi-consonant harmonic note in the early nineteenth. By the later nineteenth century the higher numbered dominant-quality dissonances had also achieved harmonic status, with resolution delayed or omitted completely. The greater autonomy of the dominant-quality dissonance contributed significantly to the weakening of traditional tonal function within a purely diatonic context."
Music written within the tonal system is generally analysed by defining a certain note as the primary or tonic note and the derived triad is the tonic chord. Other notes and chords are subservient to the tonic and in a strict hierarchy: the dominant note/chord is second in importance, others are lower down still. One example of this style of analysis is called Schenkerian analysis. However, this form of analysis cannot be applied to atonal music since the very point is to make all the notes and chords equal: there is no hierarchy. Instead, notes/chords can be described in terms of their properties and relationships at any particular moment: whether one note is higher than another, whether one chord has more notes than another, whether one chord is more widely spaced than another, and so on. One can also compare and contrast different strings of notes as transpositions (change in pitch) or inversions (change in note order) of each other. These terms are also used to compare chords. These methods of analysis have been used for centuries but became more important as music began to lose its tonal basis. One also needs to consider other aspects, such as how two or more simultaneous melodies relate to each other (counterpoint) and the same tools are used for this.
In the later 20th century, analysts started to adapt these tools to the yet more complex music being written. Musical set theory was first elaborated for tonal music [6] but was quickly applied to atonal music [7] since it simply provides concepts for categorizing musical objects (notes, chords, melodies and so on) and describing their relationship, without defining any particular note or chord as "primary". The later Transformational theory [8] uses a similar approach but concentrates on the relationships themselves. There are also theories which attempt to relate pitch and rhythm.
Compositional applications of these theories are numerous, but in the present context of post-tonal music the most important is serialism . In this system, certain notes are chosen then written in an order e.g. E–F♯–C–B♭–G–F. (Usually there is no repetition, but this is not always observed.) These notes are then used as the basis for a composition by playing them in the original order, in reverse order (retrograde), in "upside down" order (Inversion i.e. upward intervals now go down, and vice versa), or both (retrograde inversion or "reversion" [Stravinsky's term]), and then transposed up or down. Chords can also be formed out of the series and these can be treated to similar techniques. Schoenberg used these methods in what has become known as twelve-tone technique. In this, all unique twelve notes of the musical scale are played once and once only in a specified order. The serial techniques described above are then applied. [9] Later composers, such as Jean Barraqué and Pierre Boulez, sought to unify pitch and rhythm by organising the elements into sets of twelve, which resulted in what became known as total serialism. [10] See also Formula composition which describes techniques used by Karlheinz Stockhausen.
Aside from serialism, other forms of compositional technique arose such as those based on chords utilizing fourths rather than the more traditional thirds (see quartal and quintal harmony and Synthetic chord), those based on other mathematical processes (see Schillinger System) and those based on specific scales (or "modes": see hexatonic scale, Heptatonic scale, Octatonic scale and Synthetic scale). Olivier Messiaen in his work The Technique of my Musical Language developed what he called modes of limited transposition which displayed a special type of symmetry and which he used in numerous compositions.
Microtones and especially quarter tones have been used in music of the 20th and 21st centuries. These are the intervals between semitones. A full theory governing these has yet to be developed but the articles relating to these contain some of the most recent thoughts. (See 15 equal temperament, 19 equal temperament, 24 equal temperament, 34 equal temperament and 72 equal temperament.)
Transposition:
Inversion:
When viewing the following musical examples, it may help to imagine a mirror being placed between the various versions:
In music, harmony is the concept of combining different sounds together in order to create new, distinct musical ideas. Theories of harmony seek to describe or explain the effects created by distinct pitches or tones coinciding with one another; harmonic objects such as chords, textures and tonalities are identified, defined, and categorized in the development of these theories. Harmony is broadly understood to involve both a "vertical" dimension (frequency-space) and a "horizontal" dimension (time-space), and often overlaps with related musical concepts such as melody, timbre, and form.
In music theory, a scale is "any consecutive series of notes that form a progression between one note and its octave", typically by order of pitch or fundamental frequency.
In music theory, an interval is a difference in pitch between two sounds. An interval may be described as horizontal, linear, or melodic if it refers to successively sounding tones, such as two adjacent pitches in a melody, and vertical or harmonic if it pertains to simultaneously sounding tones, such as in a chord.
The chromatic scale is a set of twelve pitches used in tonal music, with notes separated by the interval of a semitone. Chromatic instruments, such as the piano, are made to produce the chromatic scale, while other instruments capable of continuously variable pitch, such as the trombone and violin, can also produce microtones, or notes between those available on a piano.
In music theory, the tritone is defined as a musical interval spanning three adjacent whole tones. For instance, the interval from F up to the B above it is a tritone as it can be decomposed into the three adjacent whole tones F–G, G–A, and A–B.
In music, a whole-tone scale is a scale in which each note is separated from its neighbors by the interval of a whole tone. In twelve-tone equal temperament, there are only two complementary whole-tone scales, both six-note or hexatonic scales. A single whole-tone scale can also be thought of as a "six-tone equal temperament".
A seventh chord is a chord consisting of a triad plus a note forming an interval of a seventh above the chord's root. When not otherwise specified, a "seventh chord" usually means a dominant seventh chord: a major triad together with a minor seventh. However, a variety of sevenths may be added to a variety of triads, resulting in many different types of seventh chords.
Musical set theory provides concepts for categorizing musical objects and describing their relationships. Howard Hanson first elaborated many of the concepts for analyzing tonal music. Other theorists, such as Allen Forte, further developed the theory for analyzing atonal music, drawing on the twelve-tone theory of Milton Babbitt. The concepts of musical set theory are very general and can be applied to tonal and atonal styles in any equal temperament tuning system, and to some extent more generally than that.
A semitone, also called a minor second, half step, or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent notes in a 12-tone scale, visually seen on a keyboard as the distance between two keys that are adjacent to each other. For example, C is adjacent to C♯; the interval between them is a semitone.
In music theory, a third is a musical interval encompassing three staff positions, and the major third is a third spanning four half steps or two whole steps. Along with the minor third, the major third is one of two commonly occurring thirds. It is described as major because it is the larger interval of the two: The major third spans four semitones, whereas the minor third only spans three. For example, the interval from C to E is a major third, as the note E lies four semitones above C, and there are three staff positions from C to E.
The intervals from the tonic (keynote) in an upward direction to the second, to the third, to the sixth, and to the seventh scale degrees of a major scale are called "major".
In music theory, a minor third is a musical interval that encompasses three half steps, or semitones. Staff notation represents the minor third as encompassing three staff positions. The minor third is one of two commonly occurring thirds. It is called minor because it is the smaller of the two: the major third spans an additional semitone. For example, the interval from A to C is a minor third, as the note C lies three semitones above A. Coincidentally, there are three staff positions from A to C. Diminished and augmented thirds span the same number of staff positions, but consist of a different number of semitones. The minor third is a skip melodically.
In music theory, a sixth is a musical interval encompassing six note letter names or staff positions, and the major sixth is one of two commonly occurring sixths. It is qualified as major because it is the larger of the two. The major sixth spans nine semitones. Its smaller counterpart, the minor sixth, spans eight semitones. For example, the interval from C up to the nearest A is a major sixth. It is a sixth because it encompasses six note letter names and six staff positions. It is a major sixth, not a minor sixth, because the note A lies nine semitones above C. Diminished and augmented sixths span the same number of note letter names and staff positions, but consist of a different number of semitones.
The intervals from the tonic (keynote) in an upward direction to the second, to the third, to the sixth, and to the seventh scale degrees (of a major scale are called major.
In music theory, an augmented sixth chord contains the interval of an augmented sixth, usually above its bass tone. This chord has its origins in the Renaissance, was further developed in the Baroque, and became a distinctive part of the musical style of the Classical and Romantic periods.
Modes of limited transposition are musical modes or scales that fulfill specific criteria relating to their symmetry and the repetition of their interval groups. These scales may be transposed to all twelve notes of the chromatic scale, but at least two of these transpositions must result in the same pitch classes, thus their transpositions are "limited". They were compiled by the French composer Olivier Messiaen, and published in his book La technique de mon langage musical.
In music, an augmented sixth is an interval produced by widening a major sixth by a chromatic semitone. For instance, the interval from C to A is a major sixth, nine semitones wide, and both the intervals from C♭ to A, and from C to A♯ are augmented sixths, spanning ten semitones. Being augmented, it is considered a dissonant interval.
In music, 53 equal temperament, called 53 TET, 53 EDO, or 53 ET, is the tempered scale derived by dividing the octave into 53 equal steps. Each step represents a frequency ratio of 21 ∕ 53 , or 22.6415 cents, an interval sometimes called the Holdrian comma.
In musical set theory, an interval vector is an array of natural numbers which summarize the intervals present in a set of pitch classes. Other names include: ic vector, PIC vector and APIC vector
Music theory analyzes the pitch, timing, and structure of music. It uses mathematics to study elements of music such as tempo, chord progression, form, and meter. The attempt to structure and communicate new ways of composing and hearing music has led to musical applications of set theory, abstract algebra and number theory.
Diatonic and chromatic are terms in music theory that are used to characterize scales. The terms are also applied to musical instruments, intervals, chords, notes, musical styles, and kinds of harmony. They are very often used as a pair, especially when applied to contrasting features of the common practice music of the period 1600–1900.
In music theory, an inversion is a rearrangement of the top-to-bottom elements in an interval, a chord, a melody, or a group of contrapuntal lines of music. In each of these cases, "inversion" has a distinct but related meaning. The concept of inversion also plays an important role in musical set theory.