Why do you sometimes hear ringing within your ears at chaotic times?

Just happened to me. Why is this?Why do you sometimes hear ringing within your ears at chaotic times?
It does begin to people at uninformed, but it usually goes away second or minutes later. Pretty much regular random stuff.
If you own a loud noise that bothers you or a constant ringing that doesn't shift away, you could have tinnitus which can be cause by a number of things. But most those who I know that have it get it from listening to music too loud or going to one too various concerts.
http://en.wikipedia.org/wiki/tinnitus...
it's caused by little fairy that ring little bells
Same here. Not constant though, only when it's too silent. I have an idea that it's because it's too quiet that you competent to hear the unheard. But mines isn't really "ringing," (like a bell, do you mean?) mines is unyielding to describe, it's like an alarm more, constant w/o breaking.
I don't exactly know why...