[jeargefef]

Yes. It's actually caused by the tiny hairs in the inside of our ears. The hairs are microscopic in size, and change polarities when they get vibrated by sound. When there is no sound (no loud enough sound, anyway) the hairs sit there with electrons 'just standing by'. It is my idea that the 'standby' electrons are what are forming the staticky noise- white noise, in fact. If you notice, when there's a storm coming, and the air pressure changes, the noise will radically change.
It is my theory (theory only) that these electrons should vary their response also by brainwaves and other, perhaps telepathic stimuli also, explaining why some people change variation in tones when others think about them, or hear hypnagogics. Perhaps astral entities excite these electrons with their fields and you can hear voices that 'sound tinny' and such. I'd suppose some radio waves would also cause a response, though that would be more complicated, considering modulation and all that.
Of course, these are all theories that go through my head when I'm bored.