Was the sound high pitched or a fluttering kind of noise?
ETA, either way, short periods of noise like that are normal, it happens to most people.
If it persists, then see a doc.
Noise like that is called tinnitus, but if you google it you'd probably come up with something like this....
CAUSES OF TINNITUS INCLUDE:
* cardiovascular disorders, such as high blood pressure
* metabolic abnormalities, such as low thyroid levels
* neurologic disorders, such as multiple sclerosis
* head trauma
* side effects caused by drugs such as aspirin, anti-convulsants, or diuretics
* psychological factors, such as depression
But it being temporary is key, so don't worry about the bad things you may find on the net.
Most of the time when there is long term ringing, there is an underlying cause. Anything from earwax buildup to any of the above maladies.