In my uni degree I have to study a variety of things one such thing is 'Presbycusis', which basically is damage to tiny hairs responsible for transmitting sound to the brain.
"Presbycusis is considered to be a disability of old age, however it is becoming much more common in younger people as our world grows noisier. The damage caused by excessively loud noises is progressive and cumulative. Each assault causes a bit more damage. Music played and listened to at deafening levels definately contributes to the deterioration of hearing receptors."
All I have to say about this is enjoy the loud music while it lasts cos we all know its worth it!