Synesthesia is an unusual phenomenon that is occasionally reported in artists and writers. In its pathological context, synesthesia is described as a confusion of the senses where the excitation of one sense triggers stimulation in a completely different sensory modality. In contrast to this pathological form, synesthesia can also be considered as a physiological behavior that involves a multimodal combination of all senses. Such an expression of sensory perception can also be considered as a natural process that contributes to the adaptation of the living organism to its environment. The author attempts to analyze the cerebral mechanisms involved in sensory perception and synesthesia.

Intersensoriality is part of the more general problem of musical meaning: How does sound relate to something outside of the world of sound? If we distinguish the “form” of sound from its “matter,” the discussion can then be divided into two parts. First, how can sound forms (shapes, profiles) suggest other temporal forms, such as movement? The hypothesis developed here is that sensorimotor experience is generalized to furnish a base, in successive layers, for identifying suggested movements that are more and more abstract. Secondly, how can a sound be said to be “hot” or “cold,” “dark” or “clear”? Metaphors concerning the matter of sound deal with a common level of synesthesia; a few stages of the historical study of this phenomenon are recalled here.

Music appeals to more than just our sense of hearing, and clearly we often associate other sensations with music. These non-sonorous sensations seem to be inseparable from the experience of music; in particular, images of movement appear to be deeply embedded in our perception and cognition of music. Explorations of mental images of music-related movement could enhance our understanding of music as a phenomenon, as well as be of practical value in various music-making tasks.