Never heard of this before but heard the episode of All In The Mind on sunday that carried the story.
“For some people the number six is red, Friday is blue, and music evokes a range of colours and shapes. Seeing sounds and hearing colours is one type of synaesthesia – where the senses are crossed. Meet an 11-year-old girl who was surprised to find out that not everyone sees colourful auras around people, and who feels that numbers have colours and personalities.”
Well worth a listen if you have the time.
http://www.abc.net.au/radionational/programs/allinthemind/synesthesia:-seeing-sounds-and-hearing-colours/9836826