Chromesthesia
A type of synesthesia in which which a nonvisual stimulus causes the individual to perceive color.
Color hearing is a form of chromesthesia.
In color hearing a musical tone elicits a color.
One well-studied case involved an art teacher who had a range of consistent linkages between tone and color.
For her, high octaves tended to evoke a lighter color value, while lower octaves evoked a darker color value.
And rapid major chord tone sequences elicited rapid flashes of colors, 'somewhat like fireworks exploding.' Ref.: Haack, P.
A., & Radocy, R.
E.
(1981).
A case study of a chromesthetic.
Journal of Research in Music Education, 29, 85-90.