In a report released Tuesday, one expert says the screams for help belong solely to the 17-year-old Martin, while another says the voices are a mix of both Martin and Zimmerman, the Palm Beach Post reported.
The experts were hired by the prosecution, and the analysis of the call could have significant ramifications on a case hinging on Zimmerman's claims he shot Martin because he feared for his life.
Martin's family said they recognize the teen's voice on the call, while Zimmerman's father says he hears his son. The 911 call was made by a bystander, who heard, but not saw, the confrontation and called the police.
The second-degree murder trial is set to begin next month.