I was a heavy cell phone user for several years, I developed tinnitus in my right ear (same ear I would hold the phone to) it thankfully resolved itself when I stopped using mobile phones. Hope this information can help someone.
Anecdotally, a hearing test performed after many years of having my earpiece in my right ear found that in the vocal frequency ranges my right ear has some hearing loss. (It was not like that before.) Which may or may not be coincidental.
It's not a stretch to think that holding a speaker–which is often far louder than it should be–right up to one's ear for extended periods every day could cause tinnitus in that ear.
