The difference in level between the instrumental score and the score of electro-acoustic transformations is due to the fact that an instrument/an ensemble of instruments directly produces a sound object determined by the writing (first-degree activity, real score) ; whereas the score transmitted by the computer takes this given object, transforms it and superimposes it on the instrumental score (second-degree activity, virtual score).
The transformation of a given object can be of several kinds
- it leaves its individuality as an object, as a component of the instrumental score, and transforms only its timbre;
- it gives it a structural extension that depends to a greater or lesser extent on the context in which it is situated.
We need to be able to select the instrumental object in its context and extract it from that context
- establish any threshold (pitch, dynamics, duration) by analyzing the instrumental phenomenon you wish to develop or modify; the relationship is thus established on the basis of theeffect/sound;
- we link the instrument to an analyzer-transmitter that takes into account performance data and the manual gestures of the instrumentalist; the relationship is thus established from the cause at the origin of the sound. The first solution is easier for very general thresholds, or very specific data (time, pitch, for example).
It plays on the notion of thresholds or screens.
The second solution is more reliable; it takes virtually no account of the uncertainty of detection, and is only called into question by the failure of the executor.
(In both cases, methods for readjustment during playback are required)
In addition to these possibilities in the very instant when the sound object is produced, there is the possibility of acting according to the memory of an event. One or more samples can be recorded:
- either to give them back as they are, modified only in their appearance or arrangement, thus respecting the order of the instrumental score, but compressing, enlarging or filtering these structures ;
- or to use these samples to create a non-instrumental score, related to the instrumental score in certain respects - particularly sound - but with its own autonomy.