Ohio has no explicit verbal requirement, but it can't hurt. We do have a duty to retreat in public. What this means, is that if simply leaving or voicing your intention to leave does not stop the attack, then you may be justified in using lethal force to stop the attack. It does NOT mean that you must retreat in every circumstance, without question. There are times when this is simply not possible. Basically, you have to convince a judge or jury that retreating wasn't a reasonable option.
Really, in most states I think most technicalities can be ignored, as long as you remember this: Shooting someone is a LAST RESORT, used when there are no other options, and it becomes abundantly clear that it's the ONLY way to avoid being SERIOUSLY injured or killed. If shooting someone was HONESTLY your last resort - no other options - then who cares what the law is? We're talking about your life. The risk of a criminal or civil trial outcome means nothing, if your other alternative was death or serious bodily injury. If you think about it, every state's requirements are likely to be met if you consider what "absolute last resort" means (leaving, voicing the intention to leave, attempt to resolve conflict by non lethal means, not being the agressor who caused the attack, etc).
So in your scanario, let's say that your state had a requirement to issue a verbal command to stop, but you've lost your voice. Shooting the attacker was THE ONLY WAY (and that means honestly, no bullshit) to stop the threat to your life. Would you really care about the verbal requirement? Do you really think you'd be convicted? Would you have rather died (last resort, remember)?