I hear panic attacks

This has to be the craziest thing that's happened in quite some time. Last night as I'm brushing my teeth I started hearing this humming noise. Sort of like a high pitched mechanical noise. Instead of thinking something like "gee, that's a high pitched mechanical noise" I immediately went to "gee, what sort of medical condition causes the hearing of high pitched mechanical noises".

The medical dictionary that is my brain could only come up with two things. Aneurysm and high blood pressure. As a matter of fact, I thing if you drew a decision tree of my medical knowledge it would look something like this:

Does your head hurt?
     |
     |
Do you have ringing
in your ears?
     |
Back pain
     
Frequent Urination
     |
     |
Swollen Uvula
     | 
Dark Eyelashes
     |
     |
You are having 
an aneurysm.  Please
make sure your affairs are
  in order.

Simple, concise, accurate. I really don't understand what the other 7 years, 364 days of medical school or for. Probably something about negotiating insurance contacts and when to use a sand wedge instead of a pitching wedge.

Anyway, turns out when I went in to a different room I couldn't hear it any more... Go figure. An aneurysm that only happens while I'm brushing my teeth.