Usually people who suffer from hearing loss do not regain their hearing. That is due the mechanism of the trauma being caused with constant suffering of loud voices. I was a peacekeeper so I had my share of noises even with the headphones on. I am also a musician and play bass. In these cases the hearing loss is caused by pressure on the inner ears system and those cells in there do not rebuild.
In cases of opiates it is suggested that it actually does not cause the same kind of damage (and even could not) and not even in the same place as normal loss of hearing due loud voices.
It actually causes damage in the cells that transmit the electronic signal from the hearing system to the brains. Therefore it is much more simple structure than the system that transforms pressure into neurosignals. I think that this kind of systeme might actually repair itself when given time. It might be even able to speed the process with the hormones that also help other brain tissue to form new signal routes.
Those are just my opinions based on the studies I read when I discovered this thread and someone called it bullshit.
