If the experts can't determine who was yelling, then the jury can't determine who was yelling.....EXCEPT....common sense says the guy that was getting his head bashed BEFORE THE SHOT was the one that was yelling. And we know absolutely that he got his head bashed and that he was on the bottom...(the back of his jacket was wet, too).
Tray didn't need any help bashing George's head...he was winning...