There's a lot of talk of language in Speaker for the Dead, but surprisingly little actual alien language. We hear bits of Portuguese, and there are Nordic terms, but we don't ever hear any actual Wives's language, or Mens's language; we don't even know what the piggies call themselves (or, for that matter, what the buggers call themselves). Other sci-fi stories (Ursula K. Le Guin's, for example—check out the ansible discussion in the "Symbols" section) invent or half invent languages to give you the feeling of an alien culture, but Card doesn't do that. Difference and alienness are all presented through our language; we speak them, not the other way around.
Questions About Language and Communication
"Piggies" and "buggers" are both borderline insults. What effect does it have to give the aliens these names? Does it make them more or less sympathetic?
What is the significance of Human's name?
The Hive Queen and the trees communicate. Do they form a community?
Chew on This
Ender's mistake in cutting Jane off shows that the most important moral value of the book is communication.
The fact that Ender speaks for the aliens shows that two-way communication is not important to the book.