If it isn’t too much trouble it would be nice to be able to disable the sounds, or have it respect the system mute state.

Damn, I would really like to try this; iOS-only is a bummer.

It looks decent. A project like this is always a great way to learn how to do something. May I suggest as your knowledge increases you could potentially build sentences in furigana across the lines as new ways to learn Japanese further.

wen web app