That's not how perfect pitch works. "Perfect pitch" is just learning and memorizing what notes sound like, so it doesn't help you recognize voices or anything like that. And the wall bonking is ridiculous, as that's obviously going to be ridiculously out of tune, which would make it harder to recognize the note and is obviously what she would have mentioned first: "You just hit the wall. That's not a musical tone; it's just a sound that happens to have a "pitch" just like any other sound would."
I have a feeling that the author might, in fact, not have a single clue how music works and just thinks of it all as, like, magic or something.