When extremely loud or repetitive sounds travel through your ear canal, they beat against your eardrum, sending waves that move minuscule hairs that convert sound into electrical impulses. Big waves can sometimes damage these tiny hairs—and they never grow back. Long or repeated exposure to sounds at or over 85 decibels can cause hearing loss—and an mp3 player at max volume tops out over 100 decibels, so turn it down.

READ MORE: Will Your Headphones Make You Go Deaf?