Something's very possibly wrong physically. Careful on the spanking advice, because think how cruel it would be if he's acting this way because something's hurting him. This is how children act when they're experiencing chronic low-grade pain. He may have headaches, or his stomach hurts, or his nerves are all inflamed. They get hyper to distract - they don't feel good if they're not being hyper. They can't hear you because they're having to manage. He could have sensory problems - if you're raising your voice, that might be painful to him if there's something wrong. They don't know how to handle when the sensory input from an external source, like another person, is painful. (For example, I can't think, my brain shuts down, if my kids are throwing fits). He's not going to listen to grownups if he's in pain and no one's helping him or comforting him or making him feel better. He's not going to tell you he's in pain, that he feels lousy, because he doesn't know that's what it is. It's not clear-cut like a boo-boo. See an osteopath, a reputable alternative doctor. Have him evaluated everywhere that you can. Follow clues until they deadend. Look hard for diet problems. For example, celiac disease (gluten intolerance) can very much cause this (gut issues cause pain, inflammatory processes affect the nervous system). Doctors have been slow to clue in about celiac.
