system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] So, what's with all of the sign language?
gpt
Also, piece of information from the book that was not in the film, some people/houses even have verbal sub languages that can be spoke in the middle of normal sentences to speak with someone from your house to alert of something while still talking to other people.

Of course this one would be almost impossible to adapt in the film, but the language have the same porpoise, to speak with someone in public without everyone knowing what you two are speaking. In the book there is an important couple that function as something like a judge of transition/other organizations overseer of some big event that have a language based on hhuumms during the speak. So, you would think these people are just slow speaking/don't know your language, while they are having full conversation about you while talking to you.

There is also one scene from the books that is also not in the film, were Paul and Jessica are having an important dinner with important people from arrakis, were the nerves were heated, and they used their own non verbal language to discuss the best way to conduct the dinner while taking to other people.