Monika, I fear you may well be right about their hearing being affected by over loud music.
Years ago, I used to go to Rock Music concerts,night clubs and the like, in the days when there was no legislation regarding decibel levels. The night club I went to 3 times a week, was so loud, you could not hear conversation...just see folks mouths moving. When I left, my ears would be ringing and everything was muffled...they would just about be recovered when I went the next time.
The result of this being, by the time I was in my late thirties, I was having difficulty in hearing conversation when there was any sort of background noise. The hearing test revealed I was becoming hard of hearing and the damage to my ears was caused by noise damage...as I have never worked in a noisy environment, the conclusion was, my love of loud rock concerts/music and my frequent visits to the nightclub has taken it's toll on my precious hearing.
Now I'm 57, the problem has only got worse, despite my taking care not to expose my poor eardrums to further assaults. While I am by no means deaf, I struggle to hear conversations on social occasions where there is any sort of background noise, be it music or just general hubbub of voices. I have to ask folks to repeat themselves several times, whilst watching their lips and it extremely annoying to only catch half of what is being said! If someone speaks to me, whilst not looking my way, I haven't a hope of hearing what they are saying.
When meeting folks for the first time, I explain my predicament instead of trying to bluff it out.
If only I had known in my youth, the damage that my love of loud music was doing....but there again...I don't suppose I would have stopped going to concerts and nightclubs!! At least todays generations are partially protected by noise level regulations in public places. It's the ones who use their gadgets with earphones, with the volume full blast and those whose cars positively throb and you can hear it coming from way down the street, that are heading for trouble with their hearing. I don't suppose they would heed warnings, any more than I would have!
Cheers.