Where Do the Words Go?

One of the scariest things for me concerning Sadie is that I have no idea where Sadie's words go?  Last week she would say "barn" so clearly to request a chance to play "Peek a Boo Barn" on the iPhone....now she does not.  Last week we had "bye" so clearly, now it is a faint whisper.  I feel like as I put words in, some fall out the other end.  I wish I knew how to make the words stick.