From VOA Learning English, this is the Health and Lifestyle report.

　　One billion teenagers and young adults around the world risk losing their hearing by listening to loud music. This is according to the World Health Organization. The U.N. agency is asking young people to turn down the volume to prevent irreversible damage to their hearing.

　　Few things get the blood pumping like good music. Many people believe louder is better if you are listening to rock and roll.

　　But experiencing really loud music, even really good music, can have a serious effect on your hearing.

　　Dr. Shelley Chadha is a specialist on hearing damage for the World Health Organization. Dr. Chadha says that the cells we use to hear, called sensory cells, can be permanently damaged by loud sounds that happen over a long period of time, or are prolonged, and happen regularly, or are habitual.

　　"When this exposure is particularly loud or prolonged or habitual, the sensory cells are damaged permanently leading to irreversible hearing loss."

　　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.

　　But what is an unsafe level of sound?

　　The WHO says there can be many kinds of unsafe levels of sound. It depends 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 told VOA when the intensity of sound increases by only three decibels, safe listening time goes down by half.

　　"If a person takes a subway to go from one place to the other for half an hour in the morning and a half an hour in the evening, and every day has to turn up the volume on his device because there is so much of noise of the train and everything around, and is listening to - let us say 100 db (decibels) for one hour every day, his hearing is going to get irreversibly damaged in a few years, in a couple of years time, for sure."

　　Simple ways to prevent irreversible hearing loss

　　Dr. Chadha says there are simple measures to protect people from unsafe sound levels. She says young people who wear earplugs during concerts can enjoy music at 90 decibels as much as they can at 110 decibels. But she admits that earplugs may not look very cool.

　　"The fact that earplugs may look un-cool may be true today, but if there is a change in behavior that may not necessarily be true in the future and wearing earplugs may actually be cool."

　　A common sense suggestion is to turn down the volume on your personal audio devices. The WHO also advises young people to limit their use of such devices to less than one hour a day. It reminds people to use their technology to stay safe. Smart phone apps can help to monitor safe listening levels.

　　The U.N. agency estimates 360 million people suffer hearing loss linked to many causes, including noise, genetic conditions, infectious diseases and aging. It notes half of all cases of hearing loss are avoidable.

　　And that's the VOA Learning English Health and Lifestyle report.

　　I'm Anna Matteo.

　　Lisa Schlein reported this story from Geneva. Anna Matteo wrote it for Learning English. Mario Ritter was the editor.