[jpfromlondon]

>that her mother is irritated

no, only that she sounds irritated, we have to assume there was information we were not party to that the girl was.

[kazinator]

That could be right. If we imagine that to be a screenplay, then the intent is that the actress portraying the mother sound irritated. It's not necessarily the intent that the daughter character is picking up on the irritation; it's an effect for the audience.