One in five high-schoolers has permanent ringing in the ears,and few take measures to protect their ears from loud music,according to a new study. Those numbers are surprisingly similar to results of a study of college-aged adults,said lead author Annick Gilles,a clinical audiologist at Antwerp University Hospital in Edegem,Belgium. Tinnitus,or ringing in the ears,caused by loud noise exposure is clearly linked to hearing damage,she said. People with permanent ringing in the ears may be able to hear the same volumes of sound as before the damage,but often have trouble separating speech sounds out of a mix of noises. For the new study,almost 4,000 Flemish high school students completed a questionnaire about temporary and permanent ringing in the ears,also answering questions about their attitudes toward loud noises and hearing protection. Three out of four kids experienced temporary tinnitus,and one in five heard ringing all the time.