I worked in a shipyard for nearly 10 years and been to a lot of metal concerts over the years, but to be honest I think it’s years of listening to music through ear buds at too high volume. People always warned me but I never listened (bad pun). It’s a good warning to anyone that has kids constantly listening through those ear pieces - they are damaging your hearing but it takes a long time to show.What do you think is the cause. Have you been exposed to high noise levels?