Headphones are part of the problem - specifically, mediocre-quality headphones such as the ones that come bundled with most MP3 players and smartphones. Loud noises can damage the tiny hairs in the inner ear, which vibrate according to sounds and transmit chemical signals through nerves to the brain. Over-shocking these hairs damages their ability to pick up sound vibrations. Repeated exposure to noises above 85 decibels can therefore cause permanent hearing loss.