What is said changes with different levels (Hayes uses an "Elemental" form here; Earth, Fire, Water, Wind, Void). "Stop it!" is taught for the "Earth" responces (firm, hold your ground type actions, so the command is dominant and unyielding), "Whoa!" for "Water" (a receding element, which is used against surprise attacks in which you initially move away from the attack, then move back in to respond), "Hey!" for "Fire" (aggresive, moving forward, with the feeling of overwhelming the opponent), and "Easy" for "Wind" (evasive, looking to defuse a situation and avoid conflict). These are taught for the usual Kiai reasons (breathing etc), with the specific words being an expression of that element, as well as having legal reasons for each of them.