Think of your child's brain as a computer. We have all experienced a slow computer or program. This can be very frustrating. What happens if you keep clicking the program you are trying to use? It takes longer because your computer has to process each and every click. Your computer can't filter out the unnecessary clicks. Your child's brain is doing the same thing. He can't filter out the extra words, so ignoring some of the requests isn't an option for him. And he can't process the language quickly enough to say, "Stop. I heard you the first time."
So give your child more thinking time and you may find that he is listening. He just needs more time to respond.