I feel skeptical, I think cats and also most dog breeds understand only pitches that sound excited, because that means walk or tummy rub or food, but the actual said words could be anything, every time
When I'm training my dog I don't consider them to actually "know" a command until they recognize the word specifically. I can say "sit", "stay", or "lie down" in the exact same tone and my dog responds differently based on the word.
Tone is just as much a part of language and there’s a good chance when teaching language you ended up teaching the tone pattern better than the phonemes. It’sa much better pattern March until you have a large vocabulary.