You don\'t hear more, you merely hear more effectively. Instead of subconsciously ignoring the small things you don\'t care about, you will take note of them, because you NEED to hear every small nuance in your environment to get by.
Once you regain your sight, you hearing would return back to \'normal\' after a certain amount of time, given that you don\'t need to rely on it.
It\'s basically the same philosophy of you listening to your music loudly, and quietly. You become more sensitive if everything is quiet, and desensitive if everything is loud. It\'s just your brain subconciously compensating for your environment.