I used to work in a very noisy factory where hearing protection was required. Noise levels well over a 100 dB, depending on where you were in the factory floor, painfully loud, and in the bands hearing is very sensitive to, 1 kHz to 2 kHz. I was always very protective of my hearing and wore 30 dB+ earplugs from before I set foot in the plant to after I exited the floor, never took em off. Some guys there did not take their hearing very seriously though, in fact, one machinist I knew used over-ear headphones to drown out the very loud factory noise with music! Once in awhile they had all of our ears tested, and my audiograms always came out pretty good, with good sensitivity out past 18 kHz, but a lot of other guys who were just too cool for hearing protection had pretty bad results, rarely being able to hear above 10 kHz. Even the younger guys had audiogram results that were troubling, but no one there took them seriously except for a handful of people.