About the german course
The German course is going from bad to worse... First and foremost, the improvement that had been implemented before (pronunciation for each word individually) was "revoked" and an essencial tool that it would turn the learning of the entries into sth more efficient by providing us with the particular and singular sound of the words was summarily taken from it.
Then, it was added up again an old voice of one guy that Duo had already used earlier but now there is not the option of a slow speech. If one is a beginner here, it will certainly take them a long time to guess what the German dude is speaking in fact.
And actually these little details end up seriously discouraging any person who's a language lover and leading them to consider about giving up.
I know that probably a lots ones will come and give their downvotes, But if so, the "I couldn't really care less" it'll always be useful!
As someone who is praticing my rusty German to keep it, whilst focussing on learning a new different language; I must say so far up to level 8 I've found the voices much clearer than most people speaking. In fact, I never used the slow button, until after I'd replayed one a few times (likely Spanish), got the answer (finally right) then suddenly noticed how easy it was, slowing the speach down. In Spanish they run the words together, so it is a big cheat.
When you live abroad or visit abroad, MOST people WILL NOT make much effort to enunciate words carefully. Part of really learning a language is developing the nack of intuition about what was said by non intellectuals or don't appear to have read the language course books.
So really I find the OP's comment a little disinguous. There are things which make life far harder for a Duolingo beginner, than those voices. You never get anything like, "ich habe, Du hast, er hat" or "wir sind, Ihr seid, Sie/sie sind"; or "der Apfel, das Wasser und die Katze" to give big clues about what is going on. Reading the comment feedback on the course, it is clear that very many beginners are really confused; without another source to go on or some major foreign language experience, simple concepts like conjugations gender of nouns is totally alien to English speakers
Your comment doesn't account for those who learn how to pronounce German based on the audio. Proper pronunciation is a key element when learning a language, even if you never reach it or it changes as you become fluent and pick up others' accents. Whatever challenges that come with verbally communicating with native German speakers will be best handled in the actual environment, rather than an accidentally fabricated one within a learning app.
When talking in real situations, there is context, there are gestures, it's not just a random sentence taken from nowhere. And not everyone taking this course is ready to be dropped alone in a place full of Germans who will not make an effort to speak slower. Anyhow, you don't have to use this feature, but it sure is useful to beginners.