Are you having a problem with your speakers, as my duolingo is not giving me any instructions. It all seems to work, but cannot hear anything. I have had my speakers checked and all is ok
I will also add that sometimes the volume drops in half when I am in the middle of a section. Can't figure any reason for that because all my other audio works. and the obvious is to check your Duolingo user settings to be sure the speaker did not somehow get turned off. That happened with my mic several times.
Have you checked other websites to see if you can hear their audio?
There are so many reasons not to hear audio. I often inadvertently press the MUTE button on top of my notebook, forget to turn up the volume on my headphones, redirect the audio to my monitor speakers, etc.
My audio is working fine, except for sound sometimes taking several seconds to download from the DuoLingo server. I attribute this to my slow connection speed and also notice they must be backing up their speakers around 03:00 (a.m. New York City time).
You may want to check with a friend who can help you troubleshoot your setup?