The idea of synesthesia, with the idea of use of multimedia, is taking an increasing importance in both daily use tools and arts system. The synesthesia concept has several meanings: the mutual fecundation of forms of expression that once were strictly separated; the knocking down of barriers and above all the attenuation of hierarchies among the significant matters, similarly to what happened when the avant-garde movements brought in the ending of the dualism noise-music in the Twenties; the assignment of an active role to the audience of the work of art, with regard to the ways of signification of the work of art itself; the overcoming of the hierarchy between senses that are supposed to be more properly cognitive (sight and hearing) and senses of "orientation" for receiving the unprocessed sensorial data, not considered like object of cultural processing. The concepts of synesthsia that have circulated in the debate about the arts and the relationship between art and technique have chosen one or the other of these different meanings. All of them are appropriate, but they have in common a basically deterministic and in some points prescriptive view. A new way of analysis could perhaps considered the tendency to the synesthesia and the tendency to a sensorial specialisation like two equally basic aspects of perception; the arts have chosen one or the other also by contemporaneous alternative tendencies in the same historical period. The drive bringing the art system to the synesthesia is more accurately understood in a systemic interpretation of the cultural processes, by whom the artistic and technological productions are considered like different but interdependent places where changes are processed.