I have a question about NIHL (Noise induced hearing loss) i have been reading up on my notes i recieved to train for my CPL exams and i am currently on the chapter of hearing. It says that the average noise level on a turbo prop aircraft can range from 90 Db to 110Db and that obviously repeated exposure to this can cause hearing problems. My question is how much is that sound reduced for the pilots wearing headphones? Or do different headphones provide a different amount of Db reduction?