Better sounding voices
I have some difficulty understanding what the woman is pronouncing during the lessons, due to the bad quality of her voice. This isn't the case in other courses, such as Irish, where I can fully understand what is being said. I think this course would be better with new, clearer recordings.
I also wish for a new French voice. Ideally, I'd like recordings with real people. Since the sentenses are fixed, I don't see why the TTS (text-to-speech) is necessary.
Voice actors are lots of money and Duo is non-profit and doesn't have much excess money, it lives on volunteers.
Actually... I asked this before (I'm sure a lot of people would be willing to contribute via voicing sentences!) but someone said they'd actually tried it before and found the test audience usually ended up preferring the computer voices :O
I heard that too, from Luis's AMA or something. I think they spend most of the money on keeping the website up and running and other costs.
The sentences are not fixed, they are constructed from patterns and a range of applicable words. Using real speakers would either mean to record each word separately and stringing that together (unnatural) or recording every permutation of every pattern (impractical).
I agree that it is unclear. Sometimes if it says in adjective, I am supposed to write it in its correct gender but the voice doesn't sound clear when saying a word in general.
I actually really like the voice on Lingvist, I find that it is really clear in it's pronunciation. Another thing that would be great, especially for gendered languages like French, would be having a male and female voice so that you get a better understanding of when the different gendered words come up in speech (male voice would say "Je suis heureux", female voice would say "Je suis heureuse").