People should listen to music for no more than one hour a day to protect their hearing, the World Health Organization suggests.
It says 1.1 billion teenagers and young adults are at risk of permanently damaging their hearing by listening to "too much, too loudly".
It said audio players, concerts and bars were posing a "serious threat".
WHO figures show 43 million people aged 12-35 have hearing loss and the prevalence is increasing.
In that age group, the WHO said, half of people in rich and middle-income countries were exposed to unsafe sound levels from personal audio devices.
Meanwhile 40% were exposed to damaging levels of sound from clubs and bars.
The proportion of US teenagers with hearing loss went from 3.5% in 1994 to 5.3% in 2006.
WHO v The Who
Dr Etienne Krug, the WHO's director for injury prevention, told the BBC: "What we're trying to do is raise awareness of an issue that is not talked about enough, but has the potential to do a lot of damage that can be easily prevented."