The judge would NOT allow the prosecution to have testimony of either of the two "expert witnesses" that were trained in voice recognition technology... Both, BTW, had previously said that whereas they could not verify the voice was Martin's that they were sure it wasn't Zimmerman's...
That ruling came before the start of the trial and has been 9mm slug to the chest of the prosecution... That's one reason why I say this trial is rigged to get Zimmerman off...
One needs to keep in mind the reality that the folks in Florida, especially those sending in big $$$ for Zimmerman's defense, didn't give a flying fig that Martin had been murdered...
"Another poor boy dead and in the ground" (Blind Lemon Jefferson) is fine with them...