Let's assume we have no idea where the audience is looking, and let's not even bother trying to make a guess or manipulate them.
What tools do we have to tell our stories?
Do It Anyway And Hope For The Best
This is the sort of advice that is both terrible yet exeedingly pragmatic. At some point in our films we are just putting a camera somewhere near a story and letting the story happen. We cut to a new scene using a dip to black or a cross fade.
Important plot points should be spoken. Characters should sound different. Spacialized audio helps but be sure to keep important audio 'unspacialized' enough that the audience is sure to hear it, if they need to.
Audio cues Narrators/voice-overs Music
Environmental story support
Looking anywhere in the scene, can an audience member take an educated guess to the current mood? Are things tense? Dramatic? Cheerful? Using the same codified signals as film - score, color grading, so on; a filmmaker can cover a lot of ground.