B.R.
My daughter is doing this, too. She does it when she is tired and overly excited, or when I am talking to my husband and not paying attention to her. I just consistantly (like the other person said) whisper to her "that's too loud, it hurts my ears." and continue to talk to my husband. Explain to me, please, exactly what you think these "pow pows" accomplish. I mean, I believe that you aren't hitting him hard enough to hurt him, but you are conveying to your son that it is okay to hit someone if they're doing something you don't like, and I guarantee that he's not learning anything from them. I'm just saying... This is a hard age, and nothing will work the first time. Be consistant, make sure he gets enough attention otherwise, and don't give him any reaction or attention when he does it other than telling him it's not okay. I guarantee he is doing it to get a reaction out of you, because often to children they don't care what kind of attention they get as long as they get it.