Florida judge weighs whether to allow voice experts in Zimmerman trial

George Zimmerman returned to court Saturday morning for the third day in a hearing that will determine whether voice-recognition experts should be allowed at his murder case.

Florida Circuit judge Debra Nelson has been listening to testimony on the issue since Thursday, and the defense still has several more witnesses to call.

The hearing is being held days before jury selection starts in Zimmerman's second-degree murder trial for fatally shooting 17-year-old Trayvon Martin in February 2012.

Zimmerman is pleading not guilty, claiming self-defense.

A British audio expert testified for the defense Saturday that it would be extremely difficult to analyze voices by comparing screaming to a normal voice.

"I've never come across a case in my 13 years where anybody's tried to compare screaming to a normal voice," said audio expert John Peter French.

French added that the voice of a person screaming is "completely different" than their normal speaking voice. "There can't be any meaningful findings," French said.

Voice experts were hired by lawyers and news organizations to analyze 911 calls made during the confrontation in which screams can be heard.

The screams are crucial pieces of evidence since they could determine who the aggressor was in the confrontation. Martin's family contends it was the teen screaming, while Zimmerman's father has said it was his son.

Audio experts have reached mixed conclusions, and defense attorneys are arguing against allowing experts who say they can match the screaming to either voice.

State expert Alan R. Reich testified Friday that it was likely Trayvon screaming in the background of the call, according to the Orlando Sentinel. "The words that were at a scream level were almost all [Trayvon]," Reich said.

However, he added that his results should not be treated as conclusive, the Orlando Sentinal reports.

In deciding whether to admit the voice-recognition technology, Nelson must determine whether it is too novel or whether it has been accepted by a community of experts.

The Associated Press contributed to this report.