The aim of the thesis is to provide an in-depth analysis of the oral, written and auditive dimension of selected novels by Joaquim Maria Machado de Assis (1839-1908), with particular emphasis on the process of gradual assimilation of modern narrative techniques, based on the written (typographical) dimension of the book, in a culture dominated by patterns of oral communication. According to the preliminary research hypothesis, the incorporation of the modern model of literary communication, which implicates distance between the sender and the receiver, took place in Brazil at the turn from the 19th to the 20th century in a way which did not erase the former model, associated with oral contexts as immediate and participative way of symbolical exchange. As this new narrative voice, seen as a "local form", will manifest itself in works by some of the most important modern Brazilian authors, a study of cultural transformations which occurred in Brazil in the late 19th century as a period of radical social and political changes (the abolition of slavery, the end of the empire and the beginning if the republic) is crucial to understand the evolution of Brazilian literature at least until the beginning of the Brazilian military dictatorship (1964). The thesis comprises five interconnected yet distinct stages. The first part (1. Modern Identity) is dedicated to the problem of the relationship between modernity, individual identity and literary representation of experience, with particular emphasis on the idea of modernity as separation from immediate reference systems. The second part (2. Auditive culture) brings a critical revision of various theoretical positions related to the interface between orality and written literature in order to discuss the concept of auditivity (Port. auditividade), proposed by L. Costa Lima (1978), and its possible usefulness in the study of Brazilian literature. The third part (3. Orality in the 19th Century) points out some aspects of oral communication pattern incorporated in the emergent literary system in 19th century Brazil and discusses a particular sense of orality in Machado de Assis' esthetical project, understood as an attitude towards the immediate, the singular and the local. The fourth part (4. The First Phase) is an attempt to analyse Machado de Assis' first four novels (Ressurreição, A mão e a luva, Helena, and Iaiá Garcia), published in the 1870s, in order to make explicit how the process of dynamical yet gradual assimilation of narrative techniques based on the written (textual) dimension of the text can be seen as parallel to the substitution of an anthropomorphic figure of the narrator as a "storyteller" and a member of the community with an impersonal and incorporeal narrative voice. The last part (5. The Second Phase) brings an analysis of Machado de Assis' two most important novels published after 1880: Memórias póstumas de Brás Cubas (1880/1881) and Dom Casmurro (1899), with some references to Casa Velha (1884-1885) and Quincas Borba (1886-1891). In the case of Dom Casmurro, perceived as the author's most complex example of the interplay between the oral, the written (textual) and the auditive, three aspects are discussed: the obliteration of explanatory chains, the narrator's apparently improvisational style, and the lacunar construction of the argument. In the final remarks, previous findings are brought together in order to propose a parallel between two dimensions of a literary work (oral and textual), two models of reader's attitude (collaborative and suspicious) and two models of identity (traditional/pre-modern and post-traditional/modern) which can be traced in Dom Casmurro, published in the first weeks of 1900 (yet dated 1899), and therefore a borderline between the two paradigms and two centuries.