A secret?

There is something in my life which I've never told anyone, except for two health professionals recently and my best friend yesterday. Now that I have my diagnosis, I needn't be afraid of telling you. What I am about to describe is not unusual for people with my type of autism.
I have already told you that I feel sounds, and the sensation is sometimes pleasant but generally otherwise, according to the sound in question. What I haven't told you until now is that when I listen to music,I see it. I don't see it like I can see the keyboard in front of me, but imagine this:
In my mind's eye I see something like a continuous roll of paper. As the music plays, so it unrolls. I see the melody as a continuous, undulating line towards the top of the roll. There is a similar line towards the bottom of the roll for the bass. The area bounded by these lines is shaded in, and I can mentally see the harmonies. As the music continues, so the roll continues to open. Listening to music demands my full attention. I can neither do anything or think of anything else while I'm listening. I have learned since that this experience is called Synesthesia.