So, how Duolingo worked before was, if the language does not have a text-to-speech, it hired a person to record 3000 sentences. The new sentences, therefore, didn't have any audio.
Recently they added an option "record audio" for contributors to submit their own audio!! This is great! I'm not sure it works though. I recorded a couple of sentences (including this one), and I can play the sound back through the Incubator (the contributors' tool), but the button up here still hasn't appeared :( Would be glad if you could also check whether there's audio now.
If it works, I would be happy if you comment on sentences without audio, so that I can record them ^_^