Some people do conflict loudly, whether due to familial or cultural roots, habit, or a low boiling point. When you want to interrupt someone’s habitual yelling during conflict, try to make the request without contributing to the fight.
Someone screamed and yelled at me in public recently. Her anger had flared and yelling is her lifelong habit. I am weary of this habit of hers, though I have experienced it directed toward me only rarely.
I said, “You mistake me for someone who will put up with being treated this way.” Then I parted company with her for a while.
I regret those words. I regret them not because they weren’t effective (they did have some impact), but because they were fighting words.
They could just have easily escalated her further, because I had thrown down the figurative gauntlet. You don’t get to talk to me like that! Stop yelling at me! All versions of the same intention: I’ll press back on you about the same amount as I think you’re pressuring me.

There are better phrases I could have used in that moment, phrases designed to interrupt a habitual behavior I was not willing to tolerate yet at the same time invoke her self-awareness instead of more wrath. Phrases like these:
I can’t hear you when you raise your voice. I prefer this to “I can’t hear you when you yell” because using the word “yell” can trigger more yelling as they defend themselves against the label. I have used this phrase many times in my mediation work and in my own life and it is very powerful. It speaks to the underlying interest: To be heard.
Ouch. This one is too short to get attention in a tirade, but if the pace of their yelling slows, this one word, said with zest, can be a show stopper. It conveys that they’re doing damage and this awareness can interrupt the pattern.
When we argue like this I can’t think straight. The power in this phrase lies in the word “we.” It invites a collaborative halt to the way things are unfolding. It says, I am by your side, here, let’s change this together.
I can hear how important this is to you. While popular culture would have you think that people yell to coerce and bully, that is not the only reason people yell. Sometimes they yell because they’re desperately trying to be heard about something important. The power of this phrase is that it acknowledges what they most want, making further yelling unneeded.
Hang on, I missed that. Tell me again. This sounds like an invitation to continue yelling, but it usually has exactly the opposite effect. When you acknowledge you’re interested in the underlying message, the histrionics can abate.
Of course, these are not the only possible phrases that could achieve results, not by a long stretch. You must discover what feels and sounds right coming out of your own mouth when you’re faced with someone who habitually does conflict loudly. Perhaps the above phrases will get you started in discovering your own impactful phrase.
I feel duty-bound to note that I am discussing a conflict situation with someone whom you do not have reason to believe is escalating to violence. If you fear violence, remove yourself from the situation.