I don't think Duo has tried, at least I've never heard about it, and you're probably right, the companies who create the voices won't want to share much info. – The team's favorite voices were from http://www.acapela-group.com/, but Duo has never integrated one of their voices so they said it would be too much extra work for them to do that. They have a lot of voices from Ivona, and I think also some from Linguatec http://www.linguatec.net/products/tts/voice_reader/vrs15demo
The voice is not quite perfect on this sentence, as of April 14th, 2018, so I've taken the liberty of re-recording it.
kon should be pronounced similar to the English "coon", not the English "con".
Please find a correct recording on http://duolingo.vydea.io/02dae4d553074ed0aae7a7f72a5d9d35.mp3
For more info on re-recordings, please check the info thread: https://www.duolingo.com/comment/23723515
Thanks for listening. Ha en bra dag! :)