Male speaking voice?
I thought having a male speaking option would be pretty neat, getting to hear some words in a different way and all. I don't know, I just wondered if it would be helpful to other people. (unless of course I'm being a dummy and that's already a thing :I)
I'm not sure, but Duolingo seems to share the same text-to-speech voice as Google Translate. In other words, I'm not sure there's an easy way to add an additional voice because the primary voice may have been a 3rd-party developer.
Nothing against it, it's a great way to speed along development of a large project. But it can also leave a lot of the control out of their hands.