Synaesthesia is the general name for a related set of various cognitive states having in common that stimuli to one sense, such as smell, are involuntarily simultaneously perceived as if by one or more other senses, such as sight or / and hearing.

Luigi Russolo (1885 - 1947), Italian futurist painter and musician and inventor of the "intonarumori" expounded his musical theories in 1913 in this manifesto entitled "L'arte dei rumori" (The Art of Noises) in which he presented his ideas about the use of noises in music.