I think it's normal to model (often times unconsciously) the behavior that is being exhibited to us. Or at least to reciprocate it in some way. I, too, tend to find that I get loud when others do. But I have noticed that if I can remain in control of the situation and remain calm when they are not - the chaos tends to calm down quicker.

The best method I could suggest is not saying anything at all. It's worked for me like a wonder. My little cousin (who is old enough to know better) finger painted chocolate in my car. Was I upset? Yes. Did I want to yell? Yes. Was there any way that me yelling could have benefited the situation at all? No. Instead, I held my tongue and in doing that was able to come up with a better solution than simply me yelling and her crying.

My T suggests that by thinking before I act, I am exhibiting "normal" behavior. So, there's a little normal/T advice for you lol. If thinks heat up. Say nothing at all. Then, once you've had to time to calmly evaluate the chaos, resolve the situation. (This has even helped me with dealing with telemarketers).