Saying the world is designed for people with hearing is causally inaccurate. Hearing evolved because sound is a useful way to perceive the world, the same way vision evolved in the spectrum it did because those are the strongest frequencies of sunlight. And more generally, I don't see many things in my everyday life with exclusively audio feedback. Usually anything designed with an audio cue just uses it to reinforce a visual one. Things we are interested in (animals, cars, etc) make noise, and we have evolved hearing in response to that. Without hearing, you have no way to be notified about things outside your field of view. This is not something we've designed about the world, it's just how that sense works.