Actually, you probably want to do something similar to what Danny Hillis did with Babble. In his case emit speech sounding zero info sounds. In this case, vibra

Actually, you probably want to do something similar to what Danny Hillis did with Babble. In his case emit speech sounding zero info sounds. In this case, vibrate similarly to a keyboard writing Lorem Ipsum (though not exactly that - then it could be filtered out). Best thing would be to train the babble-keyboard with the pattern of the specific user.