In 1948, a typical radio studio consisted of a series of record players, a disc recorder, a mixing desk, with rotating potentiometers, a mechanical reverberation, filters, and microphones. This technology made a number of limited operations available to a composer (Teruggi 2007):
- Record players: could read a sound normally and in reverse mode, could change speed at fixed ratios thus permitting octave transposition.
- Disc recorder: would record any result coming out of the mixing desk.
- Mixing desk: would permit several sources to be mixed together with an independent control of the gain or volume of the sound. The result of the mixing was sent to the recorder and to the monitoring loudspeakers. Signals could be sent to the filters or the reverberation unit.
- Mechanical reverberation: made of a metal plate or a series of springs that created the reverberation effect, indispensable to force sounds to ‘fuse’ together.
- Filters: two kinds of filters, 1/3 octave filters and, high and low-pass filters. They allow the elimination or enhancement of selected frequencies.
- Microphones: essential tool for capturing sound.
The application of the above technologies in the creation of musique concrete led to the development of a number of sound manipulation techniques including (Teruggi 2007):
- Sound transposition: reading a sound at a different speed than the one at which it was recorded.
- Sound looping: composers developed a skilled technique in order to create loops at specific locations within a recording.
- Sound-sample extraction: a hand-controlled method that required delicate manipulation to get a clean sample of sound. It entailed letting the stylus read a small segment of a record. Used in the Symphonie pour un homme seul.
- Filtering: by eliminating most of the central frequencies of a signal, the remains would keep some trace of the original sound but without making it recognisable.
The first tape recorders start arriving at ORTF in 1949; however, their functioning was much less reliable than the disc players, to the point that the Symphonie pour un homme seul, which was composed in 1950–51, was mainly composed with records, even if the tape recorder was available (Teruggi 2007, 216). In 1950, when the machines finally functioned correctly, the techniques of musique concrete 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 (Teruggi 2007, 217).