Plexus for oboe/English horn and fifteen instruments examines the thematic of the close relationship between a soloist and an ensemble, a favourite theme of the composer. The title of the piece refers to the anatomical notion of entangled nervous endings. In Les Neuf Cercles d’ Alighieri for soprano and orchestra, the singer is the mediator between the entangled orchestral tissue and the immediate listening experience. More recently, Mémoire de vague for viola and four instrumentalists aims to polarize the discourse on the soloist voice that plays a major role by its continuous presence. Plexus is situated in the line of works in which a voice provides musical continuity by dominating the development and by periodically losing itself in the instrumental mass.
The work opens with a system of repeated notes by wood-block and bells, the looping of structures of wood and brass instruments evolving at different speeds. As the soloist enters the tempo becomes unified. The English horn begins a very ornate melodic development requiring great wind and virtuosity of the player, who is omnipresent. Activity focalizes on the soloist, whose discourse is amplified and echoed by the ensemble. The repeated notes of the English horn are commented by the vibraphone, and the sustained notes underlined by the side drum. A trill by the soloist generates tremolos and arpeggios by the strings. The constant renewal of these interactions is punctuated by the recurrent and repeated chords of the tutti.
There is a calm and the instruments’ nervous reaction to the soloist subsides. Renewed energy can be felt when the English horn gives way to the oboe. Then the relationship soloist/ensemble changes : wood, brass and string instruments are clearly individualized in three rhythmically homogeneous groups. The return of the repeated tutti chords signals a new change. The relationship between the instruments is more rhythmically drowned and new timbres appear : piano, glockenspiel, rototoms. In addition, the oboe’s part is multiphonic. As a consequence, the ensemble separates again into contrasting groups that underline the intense sustained notes of the soloist. After a progression towards the climax of the piece, the ending phase marks the return of the English horn. In Plexus Denis Cohen uses sampler keyboards that produce unusual sounds that blend in with the ensemble. Notably at the beginning of the piece and the entrance of the oboe, the sounds of the shô, a Japanese mouth organ, can be heard producing a continuous high framework.

Michel Rigoni