Before the age of notated music, composition meant production of a melodic, harmonic, and / or lyrical pattern compelling enough it could be transmitted in person to other musicians. Here all that is passed on is an idea, an essence of the tune, indifferent to instrument, setting, or interpretation.
Before the age of recorded sound, composition meant the production of written instructions which could be followed by anyone who understood the relevant code. In particular, a specific array of timbres (i.e. different instruments) was assumed, as well as a particular tonal system (the Western scale).
In the age of audio recording, the composer is no longer constrained by the limitations of a system of transmission, he can produce the definitive version of a piece of music himself, adjusting all relevant parameters. In particular, he is no longer constrained to one particular set of timbres or scales.
Musique Concrète is a form of composition which could only arise in the age of audio recording. The concept behind musique concrète is that the composer begins with a set of "concrete" sounds and arranges them into a piece of music. In practice, this means the composer is not limited to the timbres available via standard instrumentation; instead, he can collect any sounds which appeal to him (of a car passing, a bird chirping, the slam of a door, a cough, running water, etc.) and arrange them into a structure constituting the finished piece of music.
Once one has decided to use "found" sounds as one's timbral palette, however, one faces a dilemma, for the theoretical structure which has developed within the western musical tradition is no longer relevant (at least not obviously so). Since this theoretical apparatus provided a structure which constrained the arrangement of sounds, some new principles must be found by which to arrange the found sounds one has chosen to work with.
(For without some principle guiding their arrangment, what is to separate the arranged sounds from their place within a natural context? ~ what will separate "music" from "noise"?)
Next: three case studies, each examining a different solution to the conceptual problem posed by musique concrète.
1. Pierre Schaeffer
2. Tetsu Inoue
3. Einstürzende Neubauten