Our inner ear hair cells pick up the mechanical energy of sound, convert it into electrical signals and transmit it to the brain. When we're born, each of us has about 30,000 such cells, and this number decreases slowly after the age of 25. But prolonged exposure to noise makes cells less sensitive. And once they're gone, they don't come back.
http://www.guardian.co.uk/society/20...alth.musicnews
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A survey in 2006 by Deafness Research UK and Specsavers concluded that 'today's youth are at risk of going deaf up to 30 years earlier than their parents because they are listening to MP3 players too loudly and too often'. They blamed the fact that 'more than 75 per cent of people own a personal music player and sophisticated sound systems in their car and homes, which allow them to blast out music day and night. We also spend more time in clubs where the noise is so loud we can barely hear the person opposite and few people, particularly in the 16- to 34-year-old age group, are aware of the damaging effect all this can have on their hearing.'