I can make a rumbling noise in my head, iin?
I've asked a few friends about this already, and they don't seem to relate.
Whenever I tense up a spot about the right side of my head (I have an incapability to tense up my left), right above my ear and behind the temple, I can hear a rumbling noise in my head. It's not in my mind, but it's something I can hear in my head.
You can emulate this rumbling sound if you put your fingers in your ears (and take out the sound of your fingers rubbing against your ear and ear hairs. For me, the rumbling sound I can make in my head has a very minimal effect on drowning out other noises.
Something else I've noticed is that I have to hold my breath to make this sound. If I inhale or exhale, I can still make the sound in my head for the first second, but then it eventually dies out, and I'm unable to make the sound until I stop breathing. This is why it might have something to do with oxygen flowing into my brain, also backed up with how I feel lightheaded when I experiment too long with making this sound whilst breathing at the same time.