One day this week, I got onto the bus downtown, and managed to get my preferred seat, the left-side one in back that faces across the aisle. I was slightly aware of a woman sitting in the right corner of the seat across the back, mostly because she was talking on her cell phone. Generally I did not notice, but along about T St. I heard that she was explaining to her interlocutor the difference between introverts and extroverts.
Perhaps we should add the category "Metrovert", one who carries on private conversations in a carrying voice on public transportation.