Yeah, definitely. [ Saves a lot of trouble. ] How many speak the language you speak, anyway? With these things, is it possible to tell?
[ Because when he wears the thing, he definitely hears perfect Clarinessian (or whatever their language may be called) yet when he looks at her mouth he can also definitely see that the words that he hears and the words shaped with her mouth are different. He won't be able to do lipreading if he doesn't know what language someone actually speaks. ]
We'd probably be very lost, it's impossible to know every language ever. By the way, what are telephones?