I think you are talking about "reactive" tinnitus here...a form of H.is that the t u get when u get exposed to something as in u feel like a static type noise on top of ur head but goes away after a while?....
Just noticed a perfect example of how common the spreading thing is - in the tinnitus and masturbation thread (ignore the masturbation part, it does not matter the cause ):
In my case , when I first started I also noticed just a little morse code that was hardly there, just in the background and couldn't even hear it until I put my finger over ear to listen. I didn't relate mine to mastubation, so continued .... Until white noise came , then the other ear.... And now it's multiple tones in each.