It's hard to overstate the importance of redundancy in natural languages. There are other factors at play, such that speech perception is multi-modal. E.g. see

It's hard to overstate the importance of redundancy in natural languages. There are other factors at play, such that speech perception is multi-modal. E.g. see: https://en.wikipedia.org/wiki/McGurk_effect https://en.wikipedia.org/wiki/McGurk_effect