I suspect the audio file would be stored on the phone and only sent to the engine via Bluetooth when needed like a Bluetooth speaker system. I doubt there is much to edit or change your voice within the app but I suppose one could edit a clip and store it on the app and use it. I imagine Dave is chomping at the bit to demonstrate this feature.
It seems similar to MTH's protocast which I never used. I can see the kids having a lot of fun with it though.