I read something once that claimed the reason hearing people talk on mobile phones compared to just hearing people have a conversation is annoying is because we only hear part of the conversation. I wonder if this is related.
Here it is:
http://news.bbc.co.uk/1/hi/technology/3643477.stm
Here it is:
http://news.bbc.co.uk/1/hi/technology/3643477.stm