Musique concrète (French: [myzik kɔ̃kʁɛt]; lit. 'concrete music') [nb 1] 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 montage. 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, metre, and so on.  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 (l'objet sonore).  By the early 1950s musique concrète was contrasted with "pure" elektronische Musik (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 (musique acousmatique) was used in reference to fixed media compositions that utilized both musique concrète based techniques and live sound spatialisation. Musique concrète influenced many popular musicians, including the Beatles, Pink Floyd, Jean-Michel Jarre, and Frank Zappa.
In 1928 music critic André Cœuroy wrote in his book Panorama of Contemporary Music that "perhaps the time is not far off when a composer will be able to represent through recording, music specifically composed for the gramophone.  In the same period the American composer Henry Cowell, in referring to the projects of Nikolai Lopatnikoff, believed that "there was a wide field open for the composition of music for phonographic discs." This sentiment was echoed further in 1930 by Igor Stravinsky, when he stated in the revue Kultur und Schallplatte that "there will be a greater interest in creating music in a way that will be peculiar to the gramophone record." The following year, 1931, Boris de Schloezer also expressed the opinion that one could write for the gramophone or for the wireless just as one can for the piano or the violin.  Shortly after, German art theorist Rudolf Arnheim discussed the effects of microphonic recording in an essay entitled "Radio", published in 1936. In it the idea of a creative role for the recording medium was introduced and Arnheim stated that: "The rediscovery of the musicality of sound in noise and in language, and the reunification of music, noise and language in order to obtain a unity of material: that is one of the chief artistic tasks of radio". 
In 1942, French composer and theoretician Pierre Schaeffer began his exploration of radiophony when he joined Jacques Copeau and his pupils in the foundation of the Studio d'Essai de la Radiodiffusion nationale. The studio originally functioned as a center for the Resistance movement in French radio, which in August 1944 was responsible for the first broadcasts in liberated Paris. It was here that Schaeffer began to experiment with creative radiophonic techniques using the sound technologies of the time.  In 1948 Schaeffer began to keep a set of journals describing his attempt to create a "symphony of noises".  These journals were published in 1952 as A la recherche d'une musique concrète, and according to Brian Kane, author of Sound Unseen: Acousmatic Sound in Theory and Practice, Schaeffer was driven by: "a compositional desire to construct music from concrete objects – no matter how unsatisfactory the initial results – and a theoretical desire to find a vocabulary, solfège, or method upon which to ground such music. 
The development of Schaeffer's practice was informed by encounters with voice actors, and microphone usage and radiophonic art played an important part in inspiring and consolidating Schaeffer's conception of sound-based composition.  Another important influence on Schaeffer's practice was cinema, and the techniques of recording and montage, which were originally associated with cinematographic practice, came to "serve as the substrate of musique concrète." Marc Battier notes that, prior to Schaeffer, Jean Epstein drew attention to the manner in which sound recording revealed what was hidden in the act of basic acoustic listening. Epstein's reference to this "phenomenon of an epiphanic being", which appears through the transduction of sound, proved influential on Schaeffer's concept of reduced listening. Schaeffer would explicitly cite Jean Epstein with reference to his use of extra-musical sound material. Epstein had already imagined that "through the transposition of natural sounds, it becomes possible to create chords and dissonances, melodies and symphonies of noise, which are a new and specifically cinematographic music". 
As a student in Cairo in the early to mid-1940s the Egyptian American composer Halim El-Dabh began experimenting with tape music using a cumbersome wire recorder. He recorded the sounds of an ancient zaar ceremony and at the Middle East Radio studios processed the material using reverberation, echo, voltage controls, and re-recording. The resulting tape-based composition, entitled The Expression of Zaar, was presented in 1944 at an art gallery event in Cairo. El-Dabh has described his initial activities as an attempt to unlock "the inner sound" of the recordings. While his early compositional work was not widely known outside of Egypt at the time, El-Dabh would eventually gain recognition for his influential work at the Columbia-Princeton Electronic Music Center in the late 1950s. 
Following Schaeffer's work with Studio d'Essai at Radiodiffusion Nationale during the early 1940s he was credited with originating the theory and practice of musique concrète. The Studio d'Essai was renamed Club d'Essai de la Radiodiffusion-Télévision Française  in 1946 and in the same year Schaeffer discussed, in writing, the question surrounding the transformation of time perceived through recording. The essay evidenced knowledge of sound manipulation techniques he would further exploit compositionally. In 1948 Schaeffer formally initiated "research in to noises" at the Club d'Essai  and on 5 October 1948 the results of his initial experimentation were premiered at a concert given in Paris.  Five works for phonograph – known collectively as Cinq études de bruits (Five Studies of Noises) including Étude violette (Study in Purple) and Étude aux chemins de fer (Study with Railroads) – were presented.
By 1949 Schaeffer's compositional work was known publicly as musique concrète.  Schaeffer stated: "when I proposed the term 'musique concrète,' I intended … to point out an opposition with the way musical work usually goes. Instead of notating musical ideas on paper with the symbols of solfege and entrusting their realization to well-known instruments, the question was to collect concrete sounds, wherever they came from, and to abstract the musical values they were potentially containing".  According to Pierre Henry, "musique concrète was not a study of timbre, it is focused on envelopes, forms. It must be presented by means of non-traditional characteristics, you see … one might say that the origin of this music is also found in the interest in 'plastifying' music, of rendering it plastic like sculpture…musique concrète, in my opinion … led to a manner of composing, indeed, a new mental framework of composing".  Schaeffer had developed an aesthetic that was centred upon the use of sound as a primary compositional resource. The aesthetic also emphasised the importance of play (jeu) in the practice of sound based composition. Schaeffer's use of the word jeu, from the verb jouer, carries the same double meaning as the English verb to play: 'to enjoy oneself by interacting with one's surroundings', as well as 'to operate a musical instrument'. 
By 1951 the work of Schaeffer, composer- percussionist Pierre Henry, and sound engineer Jacques Poullin had received official recognition and the Groupe de Recherches de Musique Concrète, Club d 'Essai de la Radiodiffusion-Télévision Française was established at RTF in Paris, the ancestor of the ORTF.  At RTF the GRMC established the first purpose-built electroacoustic music studio. It quickly attracted many who either were or were later to become notable composers, including Olivier Messiaen, Pierre Boulez, Jean Barraqué, Karlheinz Stockhausen, Edgard Varèse, Iannis Xenakis, Michel Philippot, and Arthur Honegger. Compositional "output from 1951 to 1953 comprised Étude I (1951) and Étude II (1951) by Boulez, Timbres-durées (1952) by Messiaen, Étude aux mille collants (1952) by Stockhausen, Le microphone bien tempéré (1952) and La voile d'Orphée (1953) by Henry, Étude I (1953) by Philippot, Étude (1953) by Barraqué, the mixed pieces Toute la lyre (1951) and Orphée 53 (1953) by Schaeffer/Henry, and the film music Masquerage (1952) by Schaeffer and Astrologie (1953) by Henry. In 1954 Varèse and Honegger visited to work on the tape parts of Déserts and La rivière endormie". 
In the early and mid 1950s Schaeffer's commitments to RTF included official missions that often required extended absences from the studios. This led him to invest Philippe Arthuys with responsibility for the GRMC in his absence, with Pierre Henry operating as Director of Works. Pierre Henry's composing talent developed greatly during this period at the GRMC and he worked with experimental filmmakers such as Max de Haas, Jean Grémillon, Enrico Fulchignoni, and Jean Rouch and with choreographers including Dick Sanders and Maurice Béjart.  Schaeffer returned to run the group at the end of 1957, and immediately stated his disapproval of the direction the GRMC had taken. A proposal was then made to "renew completely the spirit, the methods and the personnel of the Group, with a view to undertake research and to offer a much needed welcome to young composers." 
Following the emergence of differences within the GRMC Pierre Henry, Philippe Arthuys, and several of their colleagues, resigned in April 1958. Schaeffer created a new collective, called Groupe de Recherches Musicales (GRM) and set about recruiting new members including Luc Ferrari, Beatriz Ferreyra, François-Bernard Mâche, Iannis Xenakis, Bernard Parmegiani, and Mireille Chamass-Kyrou. Later arrivals included Ivo Malec, Philippe Carson, Romuald Vandelle, Edgardo Canton and François Bayle. 
GRM was one of several theoretical and experimental groups working under the umbrella of the Schaeffer-led Service de la Recherche at ORTF (1960–1974). Together with the GRM, three other groups existed: the Groupe de Recherches Image GRI, the Groupe de Recherches Technologiques GRT and the Groupe de Recherches Langage which became the Groupe d'Etudes Critiques.  Communication was the one theme that unified the various groups, all of which were devoted to production and creation. In terms of the question "who says what to whom?" Schaeffer added "how?", thereby creating a platform for research into audiovisual communication and mass media, audible phenomena and music in general (including non-Western musics).  At the GRM the theoretical teaching remained based on practice and could be summed up in the catch phrase do and listen. 
Schaeffer kept up a practice established with the GRMC of delegating the functions (though not the title) of Group Director to colleagues. Since 1961 GRM has had six Group Directors: Michel Philippot (1960–1961), Luc Ferrari (1962–1963), Bernard Baschet and François Vercken (1964–1966). From the beginning of 1966, François Bayle took over the direction for the duration of thirty-one years, to 1997. He was then replaced by Daniel Teruggi. 
The group continued to refine Schaeffer's ideas and strengthened the concept of musique acousmatique.  Schaeffer had borrowed the term acousmatic from Pythagoras and defined it as: "Acousmatic, adjective: referring to a sound that one hears without seeing the causes behind it".  In 1966 Schaeffer published the book Traité des objets musicaux (Treatise on Musical Objects) which represented the culmination of some 20 years of research in the field of musique concrète. In conjunction with this publication, a set of sound recordings was produced, entitled Le solfège de l'objet sonore (Music Theory of the Acoustic Object), to provide examples of concepts dealt with in the treatise.
The development of musique concrète was facilitated by the emergence of new music technology in post-war Europe. Access to microphones, phonographs, and later magnetic tape recorders (created in 1939 and acquired by the Schaeffer's Groupe de Recherche de Musique Concrète (Research Group on Concrete Music) in 1952), facilitated by an association with the French national broadcasting organization, at that time the Radiodiffusion-Télévision Française, gave Schaeffer and his colleagues an opportunity to experiment with recording technology and tape manipulation.
In 1948, a typical radio studio consisted of a series of shellac record players, a shellac record recorder, a mixing desk with rotating potentiometers, mechanical reverberation, filters, and microphones. This technology made a number of limited operations available to a composer: 
The application of the above technologies in the creation of musique concrète led to the development of a number of sound manipulation techniques including: 
The first tape recorders started arriving at ORTF in 1949; however, their functioning was much less reliable than the shellac players, to the point that the Symphonie pour un homme seul, which was composed in 1950–1951, was mainly composed with records, even if the tape recorder was available.  In 1950, when the machines finally functioned correctly, the techniques of musique concrète were expanded. A range of new sound manipulation practices were explored using improved media manipulation methods and operations such as speed variation. A completely new possibility of organising sounds appears with tape editing, which permits tape to be spliced and arranged with an extraordinary new precision. The "axe-cut junctions" were replaced with micrometric junctions and a whole new technique of production, less dependency on performance skills, could be developed. Tape editing brought a new technique called "micro-editing", in which very tiny fragments of sound, representing milliseconds of time, were edited together, thus creating completely new sounds or structures. 
During the GRMC period from 1951 to 1958, Schaeffer and Poullin developed a number of novel sound creation tools. These included a three-track tape recorder; a machine with ten playback heads to replay tape loops in echo (the morphophone); a keyboard-controlled machine to replay tape loops at twenty-four preset speeds (the keyboard, chromatic, or Tolana phonogène); a slide-controlled machine to replay tape loops at a continuously variable range of speeds (the handle, continuous, or Sareg phonogène); and a device to distribute an encoded track across four loudspeakers, including one hanging from the centre of the ceiling (the potentiomètre d'espace). 
Speed variation was a powerful tool for sound design applications. It had been identified that transformations brought about by varying playback speed lead to modification in the character of the sound material:
The phonogène was a machine capable of modifying sound structure significantly and it provided composers with a means to adapt sound to meet specific compositional contexts. The initial phonogènes were manufactured in 1953 by two subcontractors: the chromatic phonogène by a company called Tolana, and the sliding version by the SAREG Company.  A third version was developed later at ORTF. An outline of the unique capabilities of the various phonogènes can be seen here:
This original tape recorder was one of the first machines permitting the simultaneous listening of several synchronised sources. Until 1958 musique concrète, radio and the studio machines were monophonic. The three-head tape recorder superposed three magnetic tapes that were dragged by a common motor, each tape having an independent spool. The objective was to keep the three tapes synchronised from a common starting point. Works could then be conceived polyphonically, and thus each head conveyed a part of the information and was listened to through a dedicated loudspeaker. It was an ancestor of the multi-track player (four then eight tracks) that appeared in the 1960s. Timbres Durées by Olivier Messiaen with the technical assistance of Pierre Henry was the first work composed for this tape recorder in 1952. A rapid rhythmic polyphony was distributed over the three channels. 
This machine was conceived to build complex forms through repetition, and accumulation of events through delays, filtering and feedback. It consisted of a large rotating disk, 50 cm in diameter, on which was stuck a tape with its magnetic side facing outward. A series of twelve movable magnetic heads (one each recording head and erasing head, and ten playback heads) were positioned around the disk, in contact with the tape. A sound up to four seconds long could be recorded on the looped tape and the ten playback heads would then read the information with different delays, according to their (adjustable) positions around the disk. A separate amplifier and band-pass filter for each head could modify the spectrum of the sound, and additional feedback loops could transmit the information to the recording head. The resulting repetitions of a sound occurred at different time intervals, and could be filtered or modified through feedback. This system was also easily capable of producing artificial reverberation or continuous sounds. 
At the premiere of Pierre Schaeffer's Symphonie pour un homme seul in 1951, a system that was designed for the spatial control of sound was tested. It was called a relief desk (pupitre de relief, but also referred to as pupitre d'espace or potentiomètre d'espace) and was intended to control the dynamic level of music played from several shellac players. This created a stereophonic effect by controlling the positioning of a monophonic sound source.  One of five tracks, provided by a purpose-built tape machine, was controlled by the performer and the other four tracks each supplied a single loudspeaker. This provided a mixture of live and preset sound positions.  The placement of loudspeakers in the performance space included two loudspeakers at the front right and left of the audience, one placed at the rear, and in the centre of the space a loudspeaker was placed in a high position above the audience. The sounds could therefore be moved around the audience, rather than just across the front stage. On stage, the control system allowed a performer to position a sound either to the left or right, above or behind the audience, simply by moving a small, hand held transmitter coil towards or away from four somewhat larger receiver coils arranged around the performer in a manner reflecting the loudspeaker positions.  A contemporary eyewitness described the potentiomètre d'espace in normal use:
One found one's self sitting in a small studio which was equipped with four loudspeakers—two in front of one—right and left; one behind one and a fourth suspended above. In the front center were four large loops and an executant moving a small magnetic unit through the air. The four loops controlled the four speakers, and while all four were giving off sounds all the time, the distance of the unit from the loops determined the volume of sound sent out from each.
The music thus came to one at varying intensity from various parts of the room, and this spatial projection gave new sense to the rather abstract sequence of sound originally recorded. 
The central concept underlying this method was the notion that music should be controlled during public presentation in order to create a performance situation; an attitude that has stayed with acousmatic music to the present day. 
After the longstanding rivalry with the electronic music of the Cologne studio had subsided, in 1970 the GRM finally created an electronic studio using tools developed by the physicist Enrico Chiarucci, called the Studio 54, which featured the "Coupigny modular synthesiser" and a Moog synthesiser.  The Coupigny synthesiser, named for its designer François Coupigny, director of the Group for Technical Research,  and the Studio 54 mixing desk had a major influence on the evolution of GRM and from the point of their introduction on they brought a new quality to the music.  The mixing desk and synthesiser were combined in one unit and were created specifically for the creation of musique concrète.
The design of the desk was influenced by trade union rules at French National Radio that required technicians and production staff to have clearly defined duties. The solitary practice of musique concrète composition did not suit a system that involved three operators: one in charge of the machines, a second controlling the mixing desk, and third to provide guidance to the others. Because of this the synthesiser and desk were combined and organised in a manner that allowed it to be used easily by a composer. Independently of the mixing tracks (24 in total), it had a coupled connection patch that permitted the organisation of the machines within the studio. It also had a number of remote controls for operating tape recorders. The system was easily adaptable to any context, particularly that of interfacing with external equipment. 
Before the late 1960s the musique concrète produced at GRM had largely been based on the recording and manipulation of sounds, but synthesised sounds had featured in a number of works prior to the introduction of the Coupigny. Pierre Henry had used oscillators to produce sounds as early as 1955. But a synthesiser with envelope control was something Pierre Schaeffer was against, since it favoured the preconception of music and therefore deviated from Schaeffer's principal of "making through listening".  Because of Schaeffer's concerns the Coupigny synthesiser was conceived as a sound-event generator with parameters controlled globally, without a means to define values as precisely as some other synthesisers of the day. 
The development of the machine was constrained by several factors. It needed to be modular and the modules had to be easily interconnected (so that the synthesiser would have more modules than slots and it would have an easy-to-use patch). It also needed to include all the major functions of a modular synthesiser including oscillators, noise-generators, filters, ring-modulators, but an intermodulation facility was viewed as the primary requirement; to enable complex synthesis processes such as frequency modulation, amplitude modulation, and modulation via an external source. No keyboard was attached to the synthesiser and instead a specific and somewhat complex envelope generator was used to shape sound. This synthesiser was well-adapted to the production of continuous and complex sounds using intermodulation techniques such as cross-synthesis and frequency modulation but was less effective in generating precisely defined frequencies and triggering specific sounds. 
The Coupigny synthesiser also served as the model for a smaller, portable unit, which has been used down to the present day. 
In 1966 composer and technician François Bayle was placed in charge of the Groupe de Recherches Musicales and in 1975, GRM was integrated with the new Institut national de l'audiovisuel (INA – Audiovisual National Institute) with Bayle as its head. In taking the lead on work that began in the early 1950s, with Jacques Poullin's potentiomètre d'espace, a system designed to move monophonic sound sources across four speakers, Bayle and the engineer Jean-Claude Lallemand created an orchestra of loudspeakers (un orchestre de haut-parleurs) known as the Acousmonium in 1974.  An inaugural concert took place on 14 February 1974 at the Espace Pierre Cardin in Paris with a presentation of Bayle's Expérience acoustique. 
The Acousmonium is a specialised sound reinforcement system consisting of between 50 and 100 loudspeakers, depending on the character of the concert, of varying shape and size. The system was designed specifically for the concert presentation of musique-concrète-based works but with the added enhancement of sound spatialisation. Loudspeakers are placed both on stage and at positions throughout the performance space  and a mixing console is used to manipulate the placement of acousmatic material across the speaker array, using a performative technique known as sound diffusion.  Bayle has commented that the purpose of the Acousmonium is to "substitute a momentary classical disposition of sound making, which diffuses the sound from the circumference towards the centre of the hall, by a group of sound projectors which form an 'orchestration' of the acoustic image". 
As of 2010, the Acousmonium was still performing, with 64 speakers, 35 amplifiers, and 2 consoles.