The Air Force did extensive studies a number of years ago on noise and its effects . It is not just the level (Decibels) but exposure time as well . even a relatively "low" amount of noise over a protracted time period will cause fatigue and irritability and possibly some hearing loss. even if below 90 db can cause loss over a time period. you almost certainly lose some hearing in the upper ranges.by the time you realize it it will be way too late. I met a fellow yesterday , late 20's , already hard of hearing.too bad