@dorkbert, you are over-simplifying the situation. From my experience, it looks like some people (aspiring managers and over-confident sales types) have a licence to shout and yell abuse and nobody doubts their entitlement to do so. Other people who try to raise their voice are disciplined and sometimes even get fired (especially true for shy people who had, just this once, a pretty good justification to do so).
For example: Nobody will dare telling loud Howard that he is too loud. However Tina, well she is in trouble because she belongs to the group which is never allowed to raise its voice.