In a way. Either through damage or some kind of physical cause (like with me, probably my TMJ, which is fixable).
A lot of people simply don't realise they have it, then you mention it to them and they'll probably notice it.
Does it get louder when you open your mouth fully? TMJ? What about when you move your head from side to side? I may have to do the same as I'm certain it isn't hearing damage related (never go to concerts or around loud machinery etc, so never damaged my ears through hearing loss).
The random squeal you mention is probably when an 'outer' inner ear hair screws up, which causes a feedback loop in your brain. The brain fixes this by muting that entire ear for a while (which is why you get sudden ringing and go a bit deaf in that ear). Kind of amazing, really.