Earphones can be as loud as jet engine

Earphones on personal music players can reach noise levels similar to those of jet engines and may result in temporary hearing loss, British researchers say. Study leader Dr. Martine Hamann of the University of Leicester said turning the volume up too high on headphones could damage the coating of nerve cells, leading to temporary deafness. The findings, published in the Proceedings of the National Academy of Sciences, indicate the coating surrounding the nerve cells can reform -- after exposure to sound louder than 110 decibels -- letting the cells function again as normal. This means hearing loss from loud sounds could be temporary, and full hearing could return, the researchers said. "The research allows us to understand the pathway from exposure to loud noises to hearing loss," Hamann said in a statement. "Dissecting the cellular mechanisms underlying this condition is likely to bring a very significant healthcare benefit to a wide population. The work will help prevention as well as progression into finding appropriate cures for hearing loss." Nerve cells that carry electrical signals from the ears to the brain have a coating called the myelin sheath, which helps the electrical signals travel along the cell. Exposure to loud noises -- i.e. sound more than 110 decibels -- could strip the cells of this coating, disrupting the electrical signals. This means the nerves can no longer efficiently transmit information from the ears to the brain, Hamann said.