From an interdisciplinary angle that takes in both literature and theater studies, this thesis turns its gaze on both language and sound in the oeuvre of American theater director Robert Wilson in the three decades that separate two of his works: Deafman Glance (1970), a play characterized by the absence of words and sound, and Monsters of Grace II (2013), his first work for radio. Wielding theoretical propositions from postdramatic and performative theater, this analysis investigates the process by which Wilson came to reconcile himself with oral language, as well as exploring new approaches to the use of voice in theater. The central object of this study, Monsters of Grace II is examined in greater detail, be it in the context of productions at the crossroads between theater and radio or as a framework by which to investigate the material and corporeal possibilities of experimentation in radio.