This is when a sound evokes the perception of a colour. It has been recorded that an opera is like experiencing a painting. Sometimes each musical instrument has it's own colour. In bi-directional hearing, the changing of a traffic light (or robot as it is referred to in other countries) evokes a bell-like sound.
Coloured-Olfaction
This is when a smell evokes the perception of a colour. The smell of garlic may be perceived as blaze orange.
Coloured-Gustation
This is when taste evokes the perception of a colour. Something salty may be experienced as red, something sweet as bluish/purple.
Tactile-Gustation
This is when the taste of something is experienced as a shape. Grapefruit may be a twisted triangular shape (as represented below), other citrus fruit may have similar triangular qualities - an orange may be an equilateral triangle.
