I suspect that there are varying degrees of synesthesia that range from the aura you describe to full-on hallucination. I have a friend that has an aural-color

I suspect that there are varying degrees of synesthesia that range from the aura you describe to full-on hallucination. I have a friend that has an aural-color synesthesia who tells me that listening to music in the car (or for that matter having a conversation) is very difficult because the colors get in the way of her driving. In any event, perhaps even in your case you could perform that test (or another like it) statistically significantly faster than persons without synesthesia.