First of all my disability is not visible. If I were to walk into a room full of people it would be assumed that no special consideration should be given to me - and there is the problem. Were I to be in a wheel chair, or on crutches, or tapping the floor with a white cane automatic responses would kick into play at once to accommodate my obvious disability.
Second, though I know I am disabled I do not usually think like a disabled person. This problem comes from both directions. A blind person doesn't take a step without considering his or her disability. I walk into a situation thinking I'll be able to function like a normal person - and now and then that's exactly what happens, but that's rare. I believe most people with a hearing disability go through their days hoping for the best, taking their chances and swallowing the truth that they are not getting 100% of what is being said.