SANFORD (CBSMiami/AP) – A Florida judge has suspended the hearing to determine  if voice- recognition experts will be allowed to testify at George Zimmerman’s trial.

Circuit Judge Debra Nelson halted the hearing Saturday after an audio expert was unable to testify because he was stuck at an airport. The hearing will resume Monday.

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Zimmerman, the man charged in the shooting death of 17-year-old Trayvon Martin, is pleading not guilty, claiming self-defense.

The hearing will continue Monday along with the first day of jury selection in Zimmerman’s trial.

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

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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.

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 Peter French.

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