off to the mad house 4 u

This has happened to me before, and I do have problems with sleep paralysis. I'd say it's normal and nothing to worry about, as it hasn't really affected me in any way other than scaring the hell out of me at the time. It also happens just outside the state of sleep with me as well (before falling asleep or just as I'm waking up).

You might have a bit of tinnitus. This is usually described as a ringing or screeching sound in one or both ears, but in some people it takes the form of buzzing, hissing, humming, or a whistling sound; or as ticking, clicking, roaring, "crickets" or "locusts", songs, or beeping. It has also been described as a "whooshing" sound like that of wind or waves. It usually lasts more than a few seconds, however.

It's not a disease but a symptom resulting from any number of underlying causes such as ear infections, foreign objects or wax in the ear, and injury from loud noises. It is also a side-effect of some oral medications such as aspirin, and may occur due to an abnormally low level of serotonin activity.

This is probably more information than you really need, but I'm providing all of this because I happen to have a wicked case of tinnitus myself :-)

Oh I think I may have that actually! But I only hear it before I go to bed when everything is really quiet. When it is in the middle of the day, I do not notice a thing!

Generally, you won't notice tinnitus during the day because other sounds will drown it out. It's most noticeable at night -- in fact, many people will buy CDs with nature sounds for nighttime listening (rain, ocean waves, etc.) so the tinnitus isn't so overwhelming.

It gets worse with age, so if you're doing anything to contribute to the problem (like listening to very loud music regularly), you might want to lessen your exposure to high volume sounds. You might also consider having an ENT doctor have a look at your ears. Sometimes, excessive ear wax can affect hearing, and that's very easily remedied with a painless ear wash.

It's not tinnitus. There is a medical term for it and if I recall it is normal. I can't remember the term.

It happens to me at about the same incidence. Once a year or so. Just as I fall off to sleep I get an auditory hallucination of some familiar sound but fairly loud.

Don't lose sleep over it. Pun intended.