In the sphere of electroacoustic music, performance does not have exactly the same signification as in other types of music. This is because adding unusual features to existing instruments or to vocals has certain repercussions for the composer, the listener and the performer. Voice is produced directly by the body, intimately linked to the singer's personality, and so is a particularly interesting case, especially in certain set-ups, such as vocal expression as part of mixed music. In the work by Gilbert Amy, Une Saison en enfer (1979-1980, for two voices, two instrumentalists and voice recording), the accent is placed foremost on the very particular way the spoken word is musicalised. The words are not produced solely by the performer's body; they are memorised, transformed, deformed - at times unrecognisable. The notion of performance is therefore broadened and the expressive possibilities of the voice are considerably enhanced. Once it has been manipulated in this way, the voice is introduced into a complex network of relations. The performance is actually a two-step process. The first step is fully controlled by the composer, and consists in creating the recording with chosen performers. The second step, the concert itself, then confronts this initial recording-composition with the emotion specific to the setting, with other performers performing live for the audience. Lastly, the musical rendering of the meaning of the poem takes on a remarkable dimension thanks to the fertility of this system. The various voices, recorded and on the stage, express the complex imaginary world contained in the autobiographic poem. Like the personality of Rimbaud as perceived by the composer, the vocal performance of the poet is threefold, between nostalgia and infantile purity, the despair of man and the poetics of womanhood.