My little experiment, that is. I will say it here plainly: changing my tone has changed his moods. Oh, he still needs corrections and sometimes punishments, he still has occasional crankiness, but we're not sinking into the deep miry pits of prolonged irritability so hard to get out of.
I've realized that while I've always sought to avoid yelling at my child, I've never thought much about speaking impatiently. I assumed that as long as my voice wasn't loud, I was being gentle.
A cranky act from him, followed by my cranky response, would only make him more cranky. Which would make me more cranky, then him more cranky, and so on. Someone has to break the chain, and I am the adult.
At least I'm trying to be.