Yes I can see your point about it being easier for the user. But my concern is, if it is a separate package in extras, the size of which would come to nearly 700MB, each time we reflash, the user would have to redownload it from the repos again.

But if you're making the audio files as downloadable from within the app itself and it would be permanently stored somewhere in the EMMC, that would work, even after reflashes.