Also am curious what he is like at school? Any of the same problems?
Perhaps normally he has a 'quiet' life, and when others appear he is so excited he cant contain himself and wants to be heard, could you make sure he is getting attention aswell when guests come to your house, at 5 year old you also want to have a chat with him about his manners, if he is rude to you, use the time out method to show he he cannot do that .