(Many people, especially youngsters, listen to music for up to one third of their waking day, but any noise over 85 decibels can be harmful. The built-in limit to iPods is around 100dB but many people have found ways to override it.
The problem is, it's a bit like smoking; the damage is a gradual process, which means that it sneaks up on people and is only noticed when it is too late.
So, here's your chance to learn phrasal verbs by doing: Turn it down.)