Hi headphones23! I don't take Portuguese, but I hope I can see what problem this is! Does the audio work for other lessons? If it does then it's most likely a problem with DuoLingo, and you should Report a Problem at the bottom of the page (after finishing the problem) or click Support on the side. Otherwise, have you made sure that your sound is on and Speaker in Settings is on (I'm actually not sure about this setting, because I haven't turned it off before, so I don't know how it works.)? Hope this can answer your problem! :)