They usually respond by producing calls and approaching the speaker, presumably to ward of an intruder. But, of course, a frog cannot do that.

And we're not being as friendly as we usually are. We want to see how they respond.

Mr. Hyde has indicated these matters are above his pay grade. He's not making these calls on these matters; presumably the speaker is calling the shots,

If the frogs want to communicate, they have two options. One is to [croak louder]. The other is to shift frequency away from the background noise.

It shows a new example of independent evolutionary adaptation in the frogs for life in habitats filled with loud background noise.

That way they made the intruder even more aware that they were annoyed.