People you know have sound turned on on their phone at work? This seems like the first problem. No polite person enables notification sounds from their phone.
This is a slightly more complex social dynamic, and a very interesting one. In my experience, it's only the alpha dog that can have their notification sounds enabled in a group setting - i.e. the person who can get away with both not giving a crap about it being annoying to others, and with pressuring others to silence their notifications.
