INTERESTING PIECE ON SYNESTHESIA: I'm interested in this. I'm quite a synesthetist myself, experiencing sound in visual terms. (Based on my experience, this is true of most sound engineers, and many musicians). The sound of falling rain "looks" like polkadots. A kick drum hit looks kind of like an overstuffed pillow, with the shape and size varying according to tone. Electric guitars look like multicolored spaghetti.
I suspect that this is actually useful, allowing more brain processing power to go to work on a problem. I can "see" differences in sound (like the difference between two nearly-identical delay times) that I can't really hear directly. I think lots of people who work with sound have similar experiences, though I wonder whether this is developed through the work, or whether people with those characteristics tend to go into such things. Perhaps some of both, though I've experienced sound this way since I was a kid.