Transcript for Legal Victory for George Zimmerman in Trayvon Martin Case
A major rung this evening in the trial of george zimmerman accused in the murder of trayvon martin. It involves the recording of a 911 call on which screams for help can be heard. But whose screams are they? Tonight the judge ruling that the jury will have to decide that for themselves. Here's abc's gio benitez. Reporter: It's a central question in the george zimmerman trial. Who is crying for help in that 911 call? Is it zimmerman or trayvon martin? So you think he's yelling help? Yes. Reporter: Zimmerman claims that's his voice, and he shot martin in self defense last year. But the martin family and prosecutors argue it's the 17-year-old crying for help. But now a judge rules prosecutors can't bring in their voice experts. Writing in an order, there's no evidence to establish that their scientific techniques have been tested and found reliable. The two sides have battled it out. Prosecutors trying to convince the jung to allow voice experts. Defense trying to dismiss them. This is not unusual for scientists to have very different views. I don't follow the difference. The 911 recording is probably the best evidence of what happened, other than george zimmerman himself, and remember, we don't have the testimony from trayvon martin. Reporter: It's so complicated even a voice analyst abc news brought the recording to said he couldn't be sure whose voice is on the tape. Because the recording isn't clear enough. There are standards for voice identification, that this case doesn't match. Reporter: And opening statements are scheduled to begin monday morning. But now we know jurors will have to decide whose voice is on that tape, david.
This transcript has been automatically generated and may not be 100% accurate.