I think this company will end up pivoting into a B2B context before long. Hopefully they will still stick to the mission, but who knows (and I wouldn't fault them if they don't – survival comes first).
That is not a problem. Language is messy, you don't need 100% accuracy to learn. The problem is that LLM errors are fundamentally different from human errors, and you won't even know how to recognize them.
Your interlocutors can work around human errors, because they tend to follow the same patterns in same language. But they will freak out with LLM errors.
If OpenAI puts resources to language learning, they could build a great product. But 3rd party devs relying on someone's tech hasn't proven to be a good strategy.
Trying out your tool, I'd really like to know if the sound is north or southern Vietnamese. I think your tool is southern vietnamese, but idk.. I personally prefer learning southern, but all the AI TTS tools use the north dialect. Ideally, I'd like a 'pure' southern accent and not a hybrid.
For your tool, You might want to get into the way to address people (Anh, em, ba, co, etc). You seem to just use toi (which I hear vietnamese people using with each other too...) but my understanding is the (Anh/Em/Ba/etc) are more 'intimate' whereas toi is more formal/business like?
One idea I haven't tried too much of yet is making flash cards that teach me a sentence structure, but introduce new vocabulary. Learning a diaspora of phrases works for short 2-3 word ones, but when I try to learn more complex sentences, my brain isn't able to draw the patterns as nothing is connected.
For example, trying to learn "bạn tên là gì" and "nhà vệ sinh ở đâu" (from your website) is harder than learning "Bạn tên là gì?", "Bạn nghề là gì?", "Bạn số điện thoại là gì?"
The other huge challenge I have is feeling like I am making progress. I'm definitely getting better, but its pretty disheartening to study for 40+ hours and still can't pronounce words like Can Tho properly, despite knowing how to read and write.
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My email is in my profile. Feel free to reach out to me if you have more updates or want to bounce ideas.