Actually, Trayvon's girlfriend DeeDee apparently did hear the beginning of the fight. There are some of her comments here
She said that Trayvon said: "What are you following me for?" to which Zimmerman replied: "What are you doing around here?" and then she surmised that the headset fell, attributing it to Zimmerman attacking Trayvon. As far as I know, she did not publicly report hearing anything else after the headset fell.
It would appear that was the time that the physical altercation started. Does it make sense that Zimmerman would attack Trayvon at this point, or that Trayvon would attack Zimmerman? Remember, Zimmerman had the police coming. Zimmerman reported that he went for his phone. Perhaps Trayvon thought he was going for a weapon, and decided to go on the offensive.
She surmised, did she? Obviously, Trayvon terminated the call. If the headset had merely fallen, she would have been able to hear quite a lot. The shouting and the gunshot are audible on at least one of the 911 calls, which were over phones a lot further removed from the site.
Hopefully, T-Mobile has exact call times. Cell carriers keep their computer clocks dead accurate.
You don't think she would say anything at all to make Trayvon into the innocent bystander the lamestream media has been portraying him as?
Unfortunately for her, the evidence doesn't support her lies.