I have constant ringing in my ears because of a TBI.

Kids are so active they sometimes hurt themselves without realizing it. Is there any chance that your son has suffered a head trauma: struck by an object like a baseball, fallen and struck his head, had a shaking of some sort like from riding a violent amusement park ride...?

Has he been exposed to too much noise? Those IPOD ear buds can be big trouble.

Good luck to your son. I know just how annoying that ringing is!!!