The doctor in this article suffered from tinnitus for 40 years before having a stroke which cured him. The stroke did not cause any hearing loss but it did eliminate the ringing in his ears. This appears to be evidence that tinnitus lies in the brain and not the ear.
http://discovermagazine.com/2010/oct/26-ringing-in-the-ears-goes-much-deeper
http://discovermagazine.com/2010/oct/26-ringing-in-the-ears-goes-much-deeper