Slizz, do you know a thing or two about systema? I think read a few times about your interested (current or previous) about sparring or fighting. If that's the case, maybe this would be of interest:
His english is a bit broken and he makes notes of differences of sounds which sometimes is different to hear (vibrations would be a better term). However, I have experienced systema from a friend who used to practice it religiously. A unconctracted punch with loose arms is definitely far more painful than any full strength punch I've ever faced.