"I do not hear the girl."
Translation:Nie słyszę dziewczynki.
"the" has no translation. But it can (almost) always be interpreted as "this" and that's why we accept any demonstratives at all. Still, the main answer has no demonstrative.
"tą" is in the wrong case. It's either Instrumental, or the common-but-incorrect Accusative form. You need Genitive here, which is "tej".