Interesting. I think the way I feel it is that my thoat constricts to varying degrees depending on the note, as if I was singing, but I don't make any sound. Sounds strange doesn't it? But if I want to produce a sense of music in my head (and throat, I guess), that's the only way I seem to be able to do it when I'm awake.

So what I percieve is just a sense of higher than or lower than, based on how constricted my throat is. Although I do seem to perceive what I could only describe as a shadowy sense of some sort of tonal quality, but it's extremely vague.

I can't imagine playing at all, whether my eyes are open or closed. Although I can position my fingers as if I was playing even if I don't have the instrument in my hands. I guess everything originates with some sort of kinesthetic sense with me.