The amount of environmental noise that exceeds safe limits is worrying. Went to buy some firewood a few hours ago. There was a machine running breaking coal up at the depot. At maybe 30 yards I get a measurement of 88dBA on my phone. The employees were all standing next to this machine with no hearing protection. Last year on holiday, the PA system for the kid's entertainment in the evening was averaging 90dBA at maybe 40 yards with everyone's kids stood right at the front. Try taking your noise cancelling headphones off mid flight for an idea as to how loud the interior of an aircraft really is. I don't doubt that excessive volumes via headphones and earbuds is causing a lot of hearing damage, but the outside world is far from quiet.