The principles used are :

- time delaying

- harmonization

- sound shuffling

- time contracting and stretching

- time freezing

- amplitude and ring modulation

- Doppler effect

- filtering

- resonant filters

- additive synthesis

One ore more of these principles are combined in different algorithms, easy to use and commercialized by the GRM since February 1992 permitting for the first time high-quality work on a personal system in a real-time situation.

MacSoutiLs

Another important development in the last years concerns MIDI systems. MIDI code is not the best ally of acousmatic work, its instrument oriented conception makes its use not always satisfying when one wants to control parameters differently than in an instrumental situation. The idea of the MacSoutiLs came via the MAX software, developed by Opcode, that permits a powerful programming of MIDI events. A certain number of patches were programmed by Serge de Laubier, their common point is that they are capable of generating a very large amount of MIDI events when receiving a trigger command from a keyboard. These events are organized according to mechanical behaviour models as: bouncing, fortune-wheel, granulation, glissandi, repetitions and random control. A graphic interface with sliders, memories and switches permits to have a global control of these phenomena, modifying the flow of events generated by any of these models. The first package of MacSoutiLs patches is included in the version 2.5 of MAX.

The Acousmographe and the New Syter

Research goes on and parallel to the updating work on existing software, new projects are being developed. The more immediate is the Acousmographe, this is a graphic tool for acousmatic score drawing based on a sonograph. This software that is going to be issued during 1994, permits to realize very accurate sonograms of any music and a bathygram that permits to analyze sound intensity in function of time. With this two