Regarding the brain, Andrew, I think that is a very important point that you make. What I suppose music and photography have in common is that they can bridge the two hemispheres and unite complex analytical thinking with a broader, spatial experience. Both music and photography (and all art) can be purely technical... we all know what that looks/sounds like! But in order to engage deeper emotions, the thought process has to move beyond the technical/analytical part of the brain. Perhaps that is the function of the background music, for me- to remind me that there are single notes played technically and perfectly... and then there are compositions that transcend all of the technicals.