You guys may find this interesting:
One of the more fascinating mixing of the senses is a condition known as
synesthesia, which affects about one in every 2,000 people. People with synesthesia claim that real sensory experiences trigger other entirely inappropriate perceptions. For instance, they might “see” sounds, “hear” colors, or “feel” tastes. The condition is not a new one; it has been known to the scientific community for at least 300 years, although it hasn’t been much investigated until relatively recently, and some still doubt whether it is a genuine neurological condition.
A common type of synesthesia is “colored-hearing.” People with this condition see specific colors in their “mind’s eye” when they hear words, letters or numbers spoken out loud. The term “mind’s eye” is used because although these people see the colors in front of them, the colors don’t interfere with their normal vision. Another common type of synesthesia is “colored-touch.” People with this condition see colors when they feel certain objects.
http://apu.sfn.org/content/AboutSFN1...teraction.html