What do you do when someone out shouts you in an argument?

I calmly tell them that I will only continue the conversation if they conduct themselves as an adult.

I have asthma and I am not about to have an asthma attack because of their ill-mannered behavior.

What someone raises their voice, I usually excuse myself. I have a soft little voice, and I refuse to scream myself hoarse.
So if they want to stand there and yell at [b]nobody[/b], that’s on them.
On the other hand, I like the idea of a bullhorn. 📢