So check this out. Some people don't just hear music, but they see colors and geometric shapes as a visual aid. They call this neurological condition Synesthesia.
Two well known artists who suffered from it were Wassily Kandisnky and a Finnish composer named Jean Sibelius.
Agency 358 Helsinki was tasked with coming up with a visual identity for the Sibelius Academy. Since no one round the office had this condition (or LSD) they went with the next best option: Creating software that analyzed music according to pitch, timber, tempo etc, and transformed it into colors. It's kinda like they asked Sibelius himself to design the identity.