Force a de-escalation. This is done by patterning the behavior you want him to follow. If he raises his voice, do not act frightened, but respond in a calm, soft voice. This demonstrates that you are the one in control. It also has the additional affect of creating a dissonance to those observing.
When someone yells, and another cowers, it appears to the observer that the person doing the yelling is justified. However, if the person being yelled at stands their ground assertively, but not aggressively, it appears to the onlooker that the yelling is unnecessary, and the one yelling looks like a fool.
Do not try to out-shout him. Remember, the goal is to change his behavior. When you speak softly, people will naturally speak more softly, or even be silent so that they can hear you. A soft voice and relaxed posture is actually a dominant stance. It shuts down a bully very quickly. Yelling back will get you disciplined, cowering reinforces the behavior, but quiet dominance will end it.
I have used this and it is very effective.