This piece was produced at IRCAM with the help of Miller Puckette, scientific advisor, and Cort Lippe, musical assistant, and was premiered July 15 1988, at the Festival d'Avignon by Ichiro Nodaira, piano.

Pluton is the second piece of the Sonus ex Machina cycle, which includes Jupiter (for flute and computer, 1987), La Partition du Ciel et de l'Enfer (for flute, two pianos, ensemble, and electronics, 1989) and Neptune (for three percussionists, 1991).

Pluton, composed in 1987, is the point of departure for all the theoretical work that I performed at IRCAM under the heading of 'virtual scores'. For me, the aim was to integrate the dimension of performance with synthesised electronic music.

I quickly realised that this research opened a path to a field of experimentation which far surpassed the initial objective. Performance in this case is not only a way of producing discourse, but of modifying it in its own morphology. This means that at certain points, the rhythms, the harmonies, the musical structures are determined in real time by the machine according to the way the pianist plays the score. This is what evokes the name of virtual scores. The electronic score is not only based on a fixed element (tape or samples), and only certain elements are predetermined. To produce these scores, the machine performs an analysis of what the soloist is playing, and it is the confrontation of this analysis with the elements I composed, in the memory of the machine, which give rise to music.

This is in no way an improvisation. The score of the pianist is rigourously composed. But everyone knows that a performance can not be precisely predetermined, and that it is constantly subject to the vagaries and variations of tempo, rhythms, dynamics, phrasing, etc. Asking a pianist to play pianissimo or fortissimo is a subjective element which varies according to context, the performer, and the way in which the performer responds to what he or she is playing.

It is this grey zone which is detected, analysed, and then converted into sound parameters, and which is at the heart of this new concept of composition.

Pluton is composed of five large sections :

1- Toccata, the solo part based on repeated notes, is surrounded by electronic transformations of the sounds of the piano..

2-Antiphonie, in which, as indicated by the title, contemplative aspects are opposed to a second, more active toccata. First alternating, these two aspects then confront one another.

3-Séquences, in which the piano engenders and controls the sound environment, which reacts in function of probability data.

4-Modulations, where the quality of synthesised sounds depends on an acoustic analysis of the sounds of the piano.

5-Variations, starting with a long, virtuoso cadence, and then linking with a gigantic finale representing the outgrowth of the tocatta of the beginning. This last section covers almost the whole second half of the work.

First written for the 4X computer, Pluton was later transcribed for IRCAM's musical workstation. Miller Puckette wrote all the computer programmes using his Max software, for which this was the first musical application.

Conceived for diffusion through six channels, Pluton was remixed, for the CD, in stereo. Work specifically aimed at the spatialisation was undertaken in order to simulate the sound movements of the concert performance.

- Philippe Manoury, 1996 (Excerpt from the insert - CD Ondine ODE 888-2)