Reply #11: I recalled Helen Keller's observation, too, and

[Lydia Leftcoast]

since language is such a basic part of being human, the inability to hear or speak cuts one off from most of the larger world. Either one is limited to the small deaf community of fluent signers or one has to struggle to read lips (turn the TV sound off and see how well you do) and reproduce sounds they can't hear. Even if one does learn to lip read and speak, one has great difficulty following a multi-person conversation and cannot perceive ambient conversations at all.

It is extremely difficult for someone who has been profoundly deaf from birth to deal with spoken English. Some of the great lip reading and speaking success stories, such as percussionist Evelyn Glennie, lost their hearing after they had learned to speak.

Read Oliver Sacks' book about deafness for a better understanding of what so-called "prelingulally" deaf people face.

By contrast, blind children learn to speak as well as sighted children. As KamaAina pointed out, blind adults cannot drive, but the ones I have known do remarkably well getting around, interacting with people, and holding responsible jobs.