colour hearing

   Also known as coloured hearing, coloured hearing synaesthesia, sound-colour synaesthesia, opsiphonia, colour audition, and audition colorée. All these terms are used interchangeably to denote the most common variant of * synaesthesia, consisting of a *chromatism (i.e. a hallucinated colour, or coloured light) arising simultaneously with, or in succession to, a regularly perceived sound. The Hungarian-Dutch experimental psychologist Géza Révész (1878-1955) defines colour hearing as follows. "By colour hearing we understand the fixed permanent association of acoustic sensations with optical images. In persons with pronounced colour hearing, certain tonal stimuli always create involuntarily, regularly, and constantly the same colour sensation (so-called chromatisms or pho-tisms). These chromatisms or photisms can be divided into three classes, according to type: perceptual, as though the colours were actually seen; conceptual, when the colour is envisaged as an ideated sensation; and mental, when the colour comes to mind, when only its name is suggested to the conscious mind." In 1786, the physicist and mathematician Johann Leonhard Hoffman published a matching list of musical instruments and colours. Whether this list was based on actual colour hearing is unknown, but it has been referred to as the earliest known historical example of this type of synaesthesia. The oldest known written report on synaesthesia, by the Austrian philologist F.A. Nussbaumer, published in 1873, involved a case ofcolour hearing, or, more specifically * coloured music. It has been known since thelate19th century that the relation between colours and sounds tends to be systematic in individual cases of synaesthesia, but no interindivid-ual - let alone universal - relation was ever established. In general, deeper tones tend to be associated with darker colours, and higher tones with brighter ones, but this relation itself tends to vary from person to person. Moreover, some people seem to respond to timbre, others to vowels or specific musical tones. The Revue de l'Hypnotisme of December 1892 includes a case report on the transformation of audition colorée into gustation colorée (i.e. *coloured taste) in a person whose somatic condition was deteriorating at the time.

   References

   Cytowic, R.E. (2002). Synesthesia. A union of the senses. Second edition. Cambridge, MA: MIT Press.

   Parish, E. (1897). Hallucinations and illusions. A study ofthe fallacies ofperception. London: Walter Scott.

   Révész, G. (2001). Introduction to the psychology ofmusic. Translated by de Courcy, G.I.C. Mineola, NY: Dover Publications.