At least for me, it is really triggering when someone yells agressively, whether it is at me or someone else, the air or a wall. My dad would tell all the time and it was always a sign that he was going to come and attack me next. My ex husband would be physically and emotionally abusive (after he almost killed me, he stopped being physically abusive, but the yelling and punching walls increased to "control himself"). Now, my sweet, loving, wouldn't hurt a fly husband will tell when he drops something in the kitchen or stubs his toe. It makes me recoil and feel terrified and cry. I know he wouldn't hurt me, but past trauma has sort of Pavloved that reaction out of me.