I'm not sure how to put it in words but I believe a Sounder to be a "herd" living/coexisting together and when on the defensive, like Paul spoke of defending cattle behaviors to be a "Rally" The noise they make is eery and I am wanting to get it on an audio tape.
We named this local unusualy large sounder "The MOB" because that is what it reminded us of a riot where the energy grows and esculates into bigger things

the picture angle does not show all the hogs, this was kinda like what Paul was talking about where a dominant hog would charge out at the dogs and the other hogs would start moving towards the same direction, these two dogs weren't going to sit still and let that big fat sow run them over, like she was trying to do. What you can't see inthe picture were about 20-30 more sows and pigs and on the backside of them were Mr.Masons dogs baying on the other side opposite of where we were standing.