Học tiếng Anh hiệu quả, nhanh chóng: http://www.facebook.com/HocTiengAnhVOA, http://www.voatiengviet.com/section/hoc-tieng-anh/2693.html. Nếu không vào được VOA, xin hãy vào http://vn3000.com để vượt tường lửa. Các chương trình học tiếng Anh miễn phí của VOA (VOA Learning English for Vietnamese) có thể giúp bạn cải tiến kỹ năng nghe và phát âm, hiểu rõ cấu trúc ngữ pháp, và sử dụng Anh ngữ một cách chính xác. Xem thêm: http://www.facebook.com/VOATiengViet
Luyện nghe nói và học từ vựng tiếng Anh qua video. Xem các bài học kế tiếp: https://www.youtube.com/playlist?list=PLD7C5CB40C5FF0531
One billion teenagers and young adults around the world risk losing their hearing by listening to loud music. This is according to the WHO, the World Health Organization. The damage people are doing cannot be reversed, or fixed. Many people like to listen to loud music, especially rock and roll. But really loud music can have a serious effect on your hearing. Dr. Shelley Chadha is a specialist on hearing damage for the WHO. Dr. Chadha says that the cells we use to hear, called sensory cells, can be permanently damaged by loud sounds. Studies in middle-and high-income countries show nearly 50 percent of teenagers and young adults aged 12 to 35 years listen to unsafe levels of sound. They are listening on their personal audio devices as well as at concerts, nightclubs and other entertainment places. The WHO says there are many kinds of unsafe levels of sound, depending on how loud the sound is and how long you listen to it. Unsafe can mean noise levels of 85 decibels for eight hours a day or 100 decibels for just 15 minutes. Dr. Chadha says when the intensity of sound increases by three decibels, safe listening time goes down by half. She adds that people can protect themselves from unsafe sound levels by wearing earplugs during concerts. Another common sense suggestion is to turn down the volume on your personal audio devices. The WHO also advises young people to limit use of such devices to less than one hour a day. The U.N. agency estimates 360 million people suffer hearing loss linked to many causes. It notes half of all cases of hearing loss can be avoided.