(CNN) — A Florida judge has ruled that the opinion of two of the prosecution's witnesses -- audio experts who analyzed 911 calls from the night Trayvon Martin was killed -- will not be allowed at George Zimmerman's murder trial.
Zimmerman, a former neighborhood watch captain, is charged with second-degree murder in the killing of 17-year-old Martin in Sanford, Florida, on February 26, 2012. He claims he shot the teenager in self-defense.
The emergency call at the center of Judge Debra Nelson's ruling was made by a neighbor who heard the altercation between Martin and Zimmerman.
The defense has argued that the quality of the recording is not sufficient to determine whose screams are being heard in the background. Defense expert James L. Wayman provided further support for that claim Monday, testifying that the sound samples are not long or clear enough to definitively identify the speaker. Zimmerman has said he is the one heard screaming.
Wayman's assertion conflicts with the June 7 testimony of Alan Reich, who said not only are the screams not Zimmerman's but that they are likely almost entirely those of Martin. That same day, another audio analyst, Tom Owen, agreed that the person heard screaming was not Zimmerman.
The ruling means Reich and Owen will not be allowed to testify at trial.
The judge concluded that "there is no competent evidence that the scientific techniques used by Mr. Owen and Dr. Reich are generally accepted in the scientific field. There is no evidence to establish that their scientific techniques have been tested and found reliable."
However, Nelson noted that the audio can still be played during the trial, and witnesses "familiar" with the voices of Zimmerman or Martin can still be called to testify.
"It is a huge victory for the defense, no question about it," HLN legal correspondent Jean Casarez said. "This is what the defense wanted."
Opening statements in the trial will begin Monday at 9 a.m. ET.