I have tinnitus something fierce.
I've had my hearing checked, changed a couple of my meds. My BP is back into the normal range (it had been pre-hypertension for awhile due to one of the meds I was taking for my asthma.) If it's only in one ear then it's very likely an accoustic nueroma, which generally need to be removed, but fortunately are almost never malignant.
I had an C Scan--negative. They have no explanation at all, and unfortunately there is no cure.
Due to his age, I would look at aspirin use and hypertension as very likely culprits, with hearing loss being another. Have his primary care guy take a look at him first before running off to a specialist to rule out the BP or aspirin use possibilities.
Anne