The general problem addressed by this thesis is the use of the audio-haptic interaction, in order to allow blind and visually impaired users to access the visual content of a Web document. This idea emerged from the fact that all current user agents transform the visual content of a digital document into raw text that can be restituted by a synthetic speech or a Braille line. This transformation destroys the visual content of the document which often bears important information for the sighted people and should be restitued to visually impaired people. WebSound evolved from this vision. WebSound is not only a traditional user agent, but it also implements the audio-haptic interaction. The user can explore the digital document using a graphical tablet while the system responds with an auditory feedback corresponding to the location and the type of the "touched" element. Moreover, WebSound has also been developed in order to become a framework for further research in the area of Human Computer Interaction/Interface. Finally, we also present the realization of a virtual library which allows the users to listen and borrow talking books from the Bibliothèque Braille Romande of the Association pour le Bien des Aveugles et malvoyants de Genève.