The hearing to determine whether state voice experts will be included in George Zimmerman's second-degree murder trial ended without a decision on Monday.
Nelson said the remainder of the Frye hearing will be held Wednesday at 4 p.m. for the state to call a rebuttal witness.
The third defense witness, Jim Wayman of San Jose State University, was unable to testify at the June 8 hearing, prompting Nelson to delay the rest of the hearing until jury selection.
The state audio experts in question are Dr. Alan Reich, who says he hears Trayvon Martin saying "I'm begging you" in the background of the 911 calls, and New Jersey audio forensic expert Tom Owen, the expert who excluded Zimmerman as the source of the screams in the 911 calls.
The defense are hoping Wayman will be able to convince Nelson the state's voice expert didn't use common scientific practices when analyzing the screams heard in the background of a 911 call.
"Currently there is no standard for speaker recognition, so there is nothing for them to be certified to," Wayman said. "When I listen to those screams I am not willing to jump to conclusion the all those screams are being made from a single speaker."
Wayman, who has a PhD in acoustic engineering and works on voice recognition software, testified via video chat from London on Monday after another day of jury selection.
He said Reich's' use of spectrographic analysis was "given up on 40 years ago."
"I don't know this methodology, I didn't understand this methodology. I was baffled," Wayman said.
Wayman said the report contained insufficient detail for him to really understand how he even arrived at conclusion.
"A lot of this appears to be like magic to me," he said.
Wayman also said speech recognition technology needs a lot of work and that looping audio for analysis, as Owen did, is not accurate. Wayman said software doesn't exist, calling it "breathtakingly new" when defense attorney Don West asked if the methodology would be new and novel.
"I certainly would nominate the creator of this software for our highest scientific prize," Wayman said.
In questioning from state prosecutor Richard Mantei, Wayman said that he listened to the analysis for 10 minutes, saying "no analysis on those recordings could reach a reliable result."
The defense previously called forensic speech/audio expert Dr. John Peter French from the United Kingdom, who said it is difficult to do a voice comparison when someone is shouting and that you can't determine from someone's normal voice what they sound like when under severe attack.
George Doddington, voice recognition exert and electrical engineer, also previously testified for the defense, calling Reich's technique of looping the 911 call to analyze the audio as "absurd."
When asked why Doddington listened to the tapes when he doesn't evaluate forensic samples, he replied, "what got me to listen to the tapes is Dr. Reich's findings. It sounded absurd and it was."
Just before the Frye hearing, Nelson agreed with the defense's motion to keep jurors anonymous after the trial but would not rule on a specific time frame.
Zimmerman is charged with second-degree murder for fatally shooting 17-year-old Trayvon Martin during a struggle in a gated community where he lived. He is pleading not guilty, claiming self-defense.
Martin's family claim the cries came from the teen while Zimmerman's father has testified they were those of his son.