I think I know what you're talking about, I sometimes get that, for me I would describe it as a static haze kind of noise that is oh so quiet, so only noticable in absolute silence. However I find that it goes away if you make a noise and doesn't come back for a while.
Mine though might be related to an eye condition I have, it causes me to see specks hovering over my entire field of vision. It looks like very faint static and is a greeny tinge. I forget what the name for it is, seeing as it doesn't come up much as I don't notice it usually, it's so faint.
Anyway, you're not alone on this .