More than 1billion people aged from 12to 35are at the risk of losing their hearing from     1     (listen) to loud music on their audio devices. According to WHO,     2     is considered unsafe that you hear a sound that is above 85decibels for eight hours or 100decibels for 15minutes.     3     (normal), users of personal audio devices choose to set the volume between 75-105. Shelly Chadha of the WHO suggested that all smartphones should be fitted with a measurement system,     4     would tell you how much sound you’re listening to, and when you go over the limit.