They are more importent then we sometimes can belive; they make us hear people talk, music play, birds sing, the ocean roar and much more that we want to hear in our surroundings.
 

For most of us these are natural experiences. For others, these are experiences they have lost – or are losing – their ability to hear properly. What they have instead is an injury that seldom can be repaired. The hazard comes from loud sounds or noise, stored without being realized, over a long or short period of time. Much too often, the hazard is ignored.