I discovered something about myself the other day that was pretty interesting but not overly surprising . . . I do a lot of my hearing with my eyes.
As an infant I contracted spinal meningitis and was left with a few minor handicaps . . . one of which is that I am completely deaf in my left ear. Personally, I don't consider it a handicap . . . it's really a pretty cool thing. When i go to sleep at night, I can bury my good ear in my pillow and not hear a thing . . . it's awesome.
Of course, I learned to compensate for my less than perfect hearing. Growing up, because of my hearing deficit, I learned to read lips. It's a pretty cool skill to have. But, you obviously to be able to see to do it.
I didn't realize how dependent I was on seeing to hear. My boss and I were troubleshooting a network issue on the shop floor of the company where I work. Eye protection is a requirement to be in the factory and, although I can obviously see with the protective glasses on, it's not perfect. My boss had to climb up a ladder to reach the network switch that we suspected was the issue. The area we were working in has metal stamping machines and other equipment that make a lot of racket.
Anytime he spoke to me I found myself removing my glasses so that I could "hear" him better. And, although I could hear his voice, I couldn't understand what he was saying without being able to clearly see his lips.
Most people use visual cues when listening to other people speak and it does influence what they hear. But, a lot of us who have an auditory handicap use not only visual cues but can actually decipher the words people are speaking by literally reading the shapes other people's lips make when they are talking.
Just in case your curious, as far as lip reading goes, I can read the lips of people on television, the computer or movies. But, not as well as I can live and in person.