Your ears are a complex system. Just like when your eyes think it's darker, your pupils dilate, your ears have a similar method of controlling how much sound ge

Your ears are a complex system. Just like when your eyes think it's darker, your pupils dilate, your ears have a similar method of controlling how much sound gets to the sensitive bits. It's possible that ANC convinces your ear to open up a bit more, leading to damage in the frequencies that it doesn't attenuate.