Language

I got this idea, if we only had a sign language and no other form of commmunication how would it affect how we obtain knowledge? Would it hinder the meaning behind it such as you couldn't give any verbal importance to the converstation, or how you would always have to give eye contain to the speaker to understand what they are saying. Would it also depend on what type of learner you are? Like for expample I'm a visual learner so therefore I learn not for speech. Would audio learns be affected if our society was based off of that type of language. I got my idea from The Clan of Cave Bear by Jean M. Auel.