Hi Alex, lovely work. I have just started working on a similar idea, to have level-aware language support in a podcast player (extending Anytime Player) to help the listener recognise words, phrases and meaning in native content.

I'm a non-techy person learning from scratch so it's slow going but as a language learner who selfishly wants more tools to support immersion learning if you want to support audio I think something podcast based would be super interesting.