Another one to add to your list of different types of synaesthesia: visually-induced auditory synesthesia, or in plain language, hearing-motion synesthesia.

You may wish to watch the short video from Newscientistvideo on YouTube to see/hear whether you have this condition.

The research that is reported and discussed in the references listed below is the third study of synaesthesia that I am aware of in which the researchers demonstrated that a particular type of synaesthesia is a genuine difference in neurological functioning by ingeniously designing a test in which the synaesthete subjects out-performed the normal control subjects. The fact that some synaesthetes can be demonstrated to out-perform people who are neurologically normal in some tasks brings us back to the questions of why do at least 1% of the population have synaesthesia, have the genes for synaesthesia been selected by the forces of evolution, and are these genes generally useful things to have?

Researcher Melissa Saenz is quoted in Scientific American as saying “I think of these people as having an enhanced soundtrack in life”. I think I’d agree with that.


List of links about hearing-motion synaesthesia

Carpenter, Siri (2008) Seeing is Hearing: New Type of Synesthesia Discovered. Scientific American Mind. August 2008.
http://www.sciam.com/article.cfm?id=the-sound-of-sight

Hubbard, Edward M. (2008) Synaesthesia: The Sounds of Moving Patterns. Current Biology. Volume 18 Issue 15 August 5th 2008 p. R657-R659.
Abstract:
http://www.current-biology.com/content/article/abstract?uid=PIIS0960982208007963

Motluk, Alison (2008) Screensaver reveals new test for synaesthesia. NewScientist.com news service. August 4th 2008.
http://www.newscientist.com/channel/being-human/brain/dn14459-screensaver-reveals-new-test-for-synaesthesia.html

New Scientist (2008) Some synaesthetes "hear" moving dots. New Scientist. August 6th 2008 Issue 2668, p. 17.
http://www.newscientist.com/channel/being-human/mg19926685.100-some-synaesthetes-hear-moving-dots.html

Newscientistvideo (2008) Screensaver reveals new test for synaesthesia. YouTube. added August 4th 2008.
http://www.youtube.com/watch?v=hLhuRIeHj6Q

Saenz, Melissa & Koch, Christof (2008) The sound of change: visually-induced auditory synesthesia. Current Biology. Volume 18 Issue 15 August 5th 2008 p. R650-R651.
Abstract:
http://www.current-biology.com/content/article/abstract?uid=PIIS0960982208007343
Paper at Scribd:
http://www.scribd.com/doc/4601229/The-sound-of-change-visuallyinduced-auditory-synesthesia

The home page of Melissa Saenz, Ph.D. at the California Institute of Technology
(with pictures of brains and stuff)
http://www.klab.caltech.edu/~saenz/