Thought I'd post it here instead of making you go through the thread to find my answer!
FI is deaf also and he knows sign language. He grew up being able to speak and he wears a hearing aid. He can hear sounds, but not exactly understand what they mean. He can talk pretty good. He became sick at 6 months old from spinal meningitis and became deaf. His fever was at 107 and his parents were pretty sure he'd die.
I, on the other hand, am profoundly deaf and don't wear hearing aids. I was born deaf- possibly in the genes since my mom has a deaf cousin and great aunt. I use American Sign Language exclusively; and I don't really speak well. My dog understands me though!