you might also want to get the book, "SOS Help for Parents," by Lynn Clark. It tells you how to effectively use the timeout method. Essentially there is a time to talk to kids, and a time where it is counterproductive. Anytime, he raises his voice - any discussion should be over period. My guess, (based on limited info) is that you do a lot of talking which leads to him doing a lot of talking. Consequences at this age need to be immediate and consistent. The trouble with talking is that the consequences are not consistent. The book I recommended will help you establish a very workable system.
One other thought, does he have the same problem in school? Schools tend to be very immediate and consistent in their consequences. If he is also having problems at school, then more professional help might be indicated.
Communication is about what you say and what he says, not just about him. You need to break the predictable, negative pattern that has crept into place. Go get a copy of "How To Talk So Your Child Will Listen And Listen So Your Child Will Talk" for you and your husband to both read (maybe get two copies. I got mine on Amazon and it's really inexpensive, since it's been around a while and is available used.) It's a great book about breaking negative communication patterns between you and your child, and a fast read, easy to understand also. If you can't get there with just a book, you and your husband might talk to a children's therapist to see if what you are doing is in some way setting up the situation.