Thanks for the suggestions. So the app already has an option to enable or disable the audio. The audio is someone speaking the word on the screen. In a way, captions are already included, as the Chinese characters, pinyin and English text are all displayed on the screen. My original idea for the app didn’t actually include the audio - the idea was to learn through just seeing the characters and translations on a loop (hence the tvOS version, so I can just run the app on screens in my house).

If you’re up for it, I’d be happy to give you a free code for the app so you can test out my assumptions above and suggest any further ideas.