I hope this is a wake up call for smart phone users. Use that thing in public and people will shoulder surf. They hear what you say on voice calls. Sometimes its so loud I hear the other person too. Its a modern day PITA, Nails on a Chalkboard 
Guaranteed.
I use my phone in public. Very short conversations. Texts are stuff like “do we need milk?” “what’s planned for dinner?” Where RU? Absolutely nothing sensitive or private gets discussed unless I can separate myself from the crowd. Get at least ten to fifteen feet away.
YYMV but that’s reality. Anything you do in public is casually seen or observed.