it is impossible to fix now. We may hope TTS or duolingo programmers fix it , but duolingo Polish team can only turn off listening exercises for sentences with wrong audio.
I hope this isn't a silly question, but how do you know whether to translate it as "He needs a dog" or "He needs the dog"?
I think it can be understood in context, but where there's no context then it can be translated either way. Perhaps use 'to', 'ta' and 'ten' if you want to show an emphasis.