Synesthesia
The experience of involuntary sensory cross activation where the presentation of a particular stimulus elicits a secondary sensory-perceptual experience. It most commonly occurs in the association of color with linguistic stimuli such as letters, numbers, words, or music, but can also occur between other senses. Although synesthesia can be acquired or transient due to trauma or drug use, there is also a strong genetic component, with a prevalence of about 1 in 2,000 individuals and a female to male ratio of 6:1.