Do Cats Respond to Human Language?

The results of this study suggest that cats really do respond to human language, but perhaps only from humans they already know well. But what happened when they heard the strangers talking their cat or baby voices? Well, nothing. It was almost as if no one was talking to the cat at all. Even after the stranger voice switched to baby cat talk! So what does any of this even mean? And when do we get to the part where the scientists prove that cats are broken?