There is definitely some type of foreign sound/voice around the time Zimmerman says something in regard to an officer getting over there.
Could simply be something on Sean's end, however at this time Zimmerman did describe Martin to be nearby his truck so I suppose it could very well be a possibility TM did say something. With that said, one of the parts of the reenactment that always stuck out to me was Zimmerman mentioning something to the effect of Trayvon may have said something to him but he didn't hear it, his windows were up and he was talking to the dispatcher. It always struck me as odd, because it seemed irrelevant. However, the fact he pointed it out does kind of imply that perhaps he thought Martin said something as he passed his truck.
Early on, Tracy Martin mentioned that Serino told him there were words exchanged at the truck also. I've never been able to understand what that was all about, as clearly nothing of the sort took place on the NEN call besides that single foreign voice/sound that could be numerous things.
Tracy never really seemed to elaborate on this, so I'm not sure Serino was perhaps implying to him that the two exchanged words before the actual call. Who knows. I've often wondered if there was something else we're missing here that escalated the situation so quickly. But then again, with DeeDee likely on the phone at that time Martin entered into the development, it would have been likely she would have mentioned something if unfavorable words were exchanged.