Pierre Boulez in the context of "Olivier Messiaen"

Musique concrète (French pronunciation: [myzik kɔ̃kʁɛt]; lit. 'concrete music') is a type of music composition that utilizes recorded sounds as raw material. Sounds are often modified through the application of audio signal processing and tape music techniques, and may be assembled into a form of sound collage. It can feature sounds derived from recordings of musical instruments, the human voice, and the natural environment, as well as those created using sound synthesis and computer-based digital signal processing. Compositions in this idiom are not restricted to the normal musical rules of melody, harmony, rhythm, and metre. The technique exploits acousmatic sound, such that sound identities can often be intentionally obscured or appear unconnected to their source cause.

The theoretical basis of musique concrète as a compositional practice was developed by French composer Pierre Schaeffer, beginning in the early 1940s. It was largely an attempt to differentiate between music based on the abstract medium of notation and that created using so-called sound objects (French: l'objet sonore). By the early 1950s, musique concrète was contrasted with "pure" elektronische Musik as then developed in West Germany – based solely on the use of electronically produced sounds rather than recorded sounds – but the distinction has since been blurred such that the term "electronic music" covers both meanings. Schaeffer's work resulted in the establishment of France's Groupe de Recherches de Musique Concrète (GRMC), which attracted important figures including Pierre Henry, Luc Ferrari, Pierre Boulez, Karlheinz Stockhausen, Edgard Varèse, and Iannis Xenakis. From the late 1960s onward, and particularly in France, the term acousmatic music (French: musique acousmatique) was used in reference to fixed media compositions that utilized both musique concrète-based techniques and live sound spatialisation.

Indeterminacy is a composing approach in which some aspects of a musical work are left open to chance or to the interpreter's free choice. John Cage, a pioneer of indeterminacy, defined it as "the ability of a piece to be performed in substantially different ways".

The earliest significant use of music indeterminacy features is found in many of the compositions of American composer Charles Ives in the early 20th century. Henry Cowell adopted Ives's ideas during the 1930s, in works allowing players to arrange the fragments of music in a number of different possible sequences. Beginning in the early 1950s, the term came to refer to the (mostly American) movement which grew up around Cage. This group included the other members of the New York School. In Europe, following the introduction of the expression "aleatory music" by Werner Meyer-Eppler, the French composer Pierre Boulez was largely responsible for popularizing the term.

The Second Viennese School (German: Zweite Wiener Schule, Neue Wiener Schule) was a group of composers that comprised Arnold Schoenberg and his pupils, particularly Alban Berg and Anton Webern, and close associates in early 20th-century Vienna. Their music was initially characterized by late-Romantic expanded tonality and later, a totally chromatic expressionism without a firm tonal centre, often referred to as atonality; and later still, Schoenberg's serial twelve-tone technique. Using this technique when composing, Schoenberg employed all 12 tones present in Western music's chromatic scale when forming a melody, this melody being the "prime series". This method would later be enhanced in compositions by Schoenberg and his followers through permutations such as "retrogrades", "inversions", "transformations" etc. Later, composers such as Pierre Boulez drew influence from Schoenberg's technique in furthering serialization; serializing not only pitch but rhythm, articulation, and dynamics as well. Theodor Adorno said that the twelve-tone method, when it had evolved into maturity, was a "veritable message in a bottle", addressed to an unknown and uncertain future. Though this common development took place, it neither followed a common time-line nor a cooperative path. Likewise, it was not a direct result of Schoenberg's teaching—which, as his various published textbooks demonstrate, was highly traditional and conservative. Schoenberg's textbooks also reveal that the Second Viennese School spawned not from the development of his serial method, but rather from the influence of his creative example.

Julius Eastman (October 27, 1940 – May 28, 1990) was an American composer. He was among the first composers to combine the processes of some minimalist music with other methods of extending and modifying his music as in some experimental music. He thus created what he called "organic music". In compositions like Stay On It (1973), his melodic motifs were not unlike the catchy refrains of then pop music.

He studied performance and composition in New York and contributed to new music scenes in New York, Buffalo, and Chicago, touring and recording as a performer and enjoying many performances of his own music. As a conductor, musician, and vocalist, he had a close artistic relationship with Arthur Russell and worked briefly with Meredith Monk and Pierre Boulez. His voice is that of Peter Maxwell Davies' Mad King on Nonesuch Records. He worked in a variety of musical styles, including classical, jazz, and crossover.

Aleatoricism (or aleatorism) is a term for musical compositions and other forms of art resulting from "actions made by chance".

The term was first used "in the context of electro-acoustics and information theory" to describe "a course of sound events that is determined in its framework and flexible in detail", by Belgian-German physicist, acoustician, and information theorist Werner Meyer-Eppler. In practical application, in compositions by Mozart and Kirnberger, for instance, the order of the measures of a musical piece were left to be determined by throwing dice, and in performances of music by Pousseur (e.g., Répons pour sept musiciens, 1960), musicians threw dice "for sheets of music and cues". However, more generally in musical contexts, the term has had varying meanings as it was applied by various composers, and so a single, clear definition for aleatory music is defied. The term was popularised by the musical composer Pierre Boulez, but also Witold Lutosławski and Franco Evangelisti.

Richard Vance Maxfield (February 2, 1927 – June 27, 1969) was a composer of instrumental, electroacoustic, and electronic music.

Born in Seattle, Maxfield studied at Stanford University, University of California, Berkeley (with Roger Sessions) and privately with Ernst Krenek in Los Angeles. A Hertz Prize travel scholarship allowed Maxfield to travel to Europe, where he met Pierre Boulez, Karlheinz Stockhausen and Luigi Nono. In 1953 he studied at Tanglewood with Aaron Copland. In 1954–55 he studied at Princeton University with Sessions and his pupil Milton Babbitt. A Fulbright Scholarship allowed Maxfield to live in Europe between 1955 and 1957, where he studied with Luigi Dallapiccola and Bruno Maderna, lived for a brief period with Hans Werner Henze and met John Cage and David Tudor. In 1958, he attended Cage's courses at the New School for Social Research (now The New School). In 1959 he taught classes there himself, becoming the first American to teach purely electronic music (as opposed to electroacoustic music based on musique concrète-style recordings with microphones).