The theories of the second half of the last century analyze the structures of literary discourses, their possible interaction with the public and the process of "interpretative cooperation". The semiotic reflection, originating in linguistics, views the works of art as "texts", i.e. "sign textures", characterized by "figures", regularities and divergences. This perspective appears suitable to the contemporary musical repertoire, whose pieces can be interpreted as chains of abstract repeated (and varied) sound structures. The interest of some composers (Boulez, Donatoni, Sciarrino, Ferneyhough) for the concept of figure suggests that rhetorics can describe the regularities and irregularities of the pieces and stress the "interpretative cooperation" process. The analysis of Éclat by Pierre Boulez, carried out according to these principles, aims at an understanding of its formal structures, seeking answers to the hypothetical questions of a self-conscious listener trying to recover the constructive strategies of the piece. The coincidence of results from perception tests on the same piece with those of the rhetoric analysis evidences the plausibility of the hypothesis.