Post-tonal music theory

Atonality in its broadest sense is music that lacks a tonal center, or key. Atonality, in this sense, usually describes compositions written from about the early 20th century to the present day, where a hierarchy of harmonies focusing on a single, central triad is not used, and the notes of the chromatic scale function independently of one another. More narrowly, the term atonality describes music that does not conform to the system of tonal hierarchies that characterized European classical music between the seventeenth and nineteenth centuries. "The repertory of atonal music is characterized

musical scale with twelve pitches, each a semitone above or below another

scale in which each note is separated from its neighbors by a whole tone; in 12-tone equal temperament, there are only two complementary whole tone scales

Microtonality is the use in music of microtones — intervals smaller than a semitone, also called "microintervals". It may also be extended to include any music using intervals not found in the customary Western tuning of twelve equal intervals per octave. In other words, a microtone may be thought of as a note that falls "between the keys" of a piano tuned in equal temperament.

a particular musical chord used by Richard Wagner

musical chord comprising at least three adjacent tones in a scale

representation of music through the use of visual symbols outside the realm of traditional music notation

musical scale with 8 pitches per octave

musical modes or scales that fulfill specific criteria relating to their symmetry and the repetition of their interval groups

six-note synthetic chord that appears in compositions by Alexander Scriabin

thumb|300x300px|Fred Steiner's 1957 Perry Mason theme, "[[Park Avenue Beat", ends with a polychord quoted by Frank Zappa in "Jezebel Boy", Broadway the Hard Way (1988) and described by Walter Everett as "juicy". ]]In music and music theory, a polychord consists of two or more chords, one on top of the other. In chord notation, polychords are written with the top chord above a line and the bottom chord below, for example, F over C (shown below) is notated as .

alt=Detail from "Farben", 3rd movement of Arnold Schoenberg's Fünf Orchesterstücke Op. 16 (1909).|thumb|Detail from "Farben", 3rd movement of Arnold Schoenberg's Fünf Orchesterstücke Op. 16 (1909). Klangfarbenmelodie (German for "sound-color melody") is a musical concept that treats timbre as a melodic element. Arnold Schoenberg originated the idea. It has become synonymous with the technique of fragmenting a melodic line between different timbres.