> Will Grunts (and other Covenant races) speak English (or other human languages), or will they speak their native tongues?
> For the most part, Covenant characters will not speak English. However, Grunts are, as they have always been, curious, and will learn the human equivalents for important words. (In other words, when you HEAR English coming from a Grunt, pay attention.)
http://halo.bungie.org/misc/random_questions_at_e32012.html
so the grunts will speak little english