Watch this short video of an 8-month-old baby who is suddenly able to hear. It's heart-warming.
This doesn't quite compare, but it reminds me of my father's reaction when, in his mid-50s, he had surgery on his ear. He had lost about 80 percent of his hearing in both ears when he was about 17. In about 1964 or 1965, we were watching a Canadian science show--I think it was "The Nature of Things"--that showed a new operation that could partially restore hearing. My father thought it could apply to him and he looked into it. It did and so he got the surgery. There was not a long wait because this was a few years before Canada got its government-payer program for health care. We lived on a busy street and he had the surgery in the fall. When he came home, he said that hearing people walk outside with their feet crunching the fall leaves sounded to him like little explosions.