On a vaguely related note, there seems to be a bias towards bass notes for many of the visuals. When I'm listening to just trumpets (and upper register trombones) some of the visuals (the "cloudy" ones, and tripping prisoner in particular) exhibit no response at all. It just feels a bit weird when you've got loud, fast music playing and the visual remains completely blank. I expect the same thing would happen with chamber music for strings, but I don't listen to much of that.

Richard.