if you submit yourself to loud noise/music for long periods of time on a regular basis, you will sustain hearing damage. so you can get this from listening to loud music, using power tools, standing near an aeroplane taking off etc etc.
anything over about 90dB is very dangerous. (im THINK i got that number right)
as infants, our hearing range is from 20Hz - 20kHz. by the time we are in our late teens, our hearing range is typically 30Hz - 17kHz.....this is because of the hearing damage we have sustained just by daily living. living in noisy cities and just living in a wold which is generally pretty loud.
a humans most sensative hearing frequency is 2.86kHz. usually, this is where the notch (hearing damage) is initially sustained.
the suggestion is to use hearing protection. cotton buds and other cheap hearing protection will not work sufficiantly for a sound engineer as high frequencies will be muffled and only the low frequencies will be heard. there are however specially made hearing protection which is moded to your ear and lowers the volume level of noises across the whole spectrum (human hearing range) equally and evenly. they cost a pretty penny but are aparently wll worth it, especially for audio engineers who depend on hearing so much. they are actually concidered to be a "tool of the trade" amongst audio engineers these days and youd be suprised to see how many actualy use them.