Do you have this? Have you ever experienced something like it?
I sometimes experience mild-ish forms of it with music and some letters and numbers. Most of the time, it's fleeting flashes of colour at some notes, but most of the time certain songs seem to be so powerfully one colour. For example, the other day I was listening to Pretty Girls Make Graves and whenever I listened to something off their first EP or Good Health all I could see was gold. Glittering, wonderful gold everywhere: I was picturing them playing the songs in my head and they were all gold and the room was gold. It was amazing how vividly it stood out in my head. Usually, I can only see the colour of music as I'm listening to the music but this has stuck in my head for a while.
I'm going to listen to lots of music now and write down the colours I see. What can you see?