As a language hunter, you’re focused on absorbing a language into your mind and body, not just knowing the grammar or vocabulary.
This is how human beings most quickly learn languages, by using all of their senses. This is how correct pronunciation is acquired. Just listening to the sound of a language can only get you so far (and only reading the pronunciation from a dictionary or other won’t get you very far at all). You need to see a speaker making the sounds, see how their body moves, and see the shape of their lips and mouth.
One of the best examples of this is the McGurk Effect – a phenomenon where your brain goes out of its way to boost what you hear, with what you see, to the extent of creating an illusion in certain situations.
Though in this case it’s demonstrated as an “illusion”, an obstacle to hearing what’s actually said, in a normal language hunting conversation you can think of tq “Read my lips” as a massive boost in clarity to what you are hearing. Your eyes confirm (and underscore) what your ears hear.