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If the sentence is garbled/muffled, which I will poorly attempt to represent in text by
l__'s g_ for _ wa__
a human is likely to still understand it. A dog would not (I assume, I am no dog researcher). So, a human’s understanding of the “correct” ungarbled sounds is not the same as a dogs, otherswise the dog would understand the garbled sounds.
Yes, if you assume something is true then you can conclude that it is true.