Having experienced this for several years (one does get ued to it... sort of) in both ears. My ENT Dr. here in the U.S. also confirms there is no cure. In most cases and certainly in mine, the culprit is exposure to loud noises, especially those percussive in nature (in my case, probably extensive use of firearms as a youth) and possibly a viral infection (not applicable in my case).
I realize that individual descriptions can be questionable in nature, but I do find that certain foods aggravate and make the condition more noticeable. With my particular version of the nerve damage salty foods or those containing vinegar will certainly increase the perception of the sound. My case is also due to my employment, which is in aviation. When I learned to fly and several years of flying large, round-engined (read noisy) airplanes with no hearing protection (no one thought about it at the time) participated to the increase in the detectability of the condition.
Also, usually accompaning the sound is a loss of higher frequency sound detection. Now, that drives one up the wall. The loss affects clear understanding of human speech, especially if there's nearby background noise.
Best of luck!