This final hearing before the trial was called for by the Zimmerman defense, arguing that the science involving picking out certain audio is inadmissible or is so new that it shouldn't be allowed by a jury. The state contends that its audio experts are credible, and that it should be up to a jury to decide what to believe.
Shawn Vincent, spokesman for Zimmerman's lawyer Mark O'Mara, told ABC News, "That 911 call will get played in court. It is an important piece of evidence that will be played for the jury to make up their mind."
"The 911 call is probably the best evidence of what happened that night besides George Zimmerman's testimony and Trayvon's," said legal analyst Bill Schaefer, who noted Martin wouldn't be able to testify explaining his version of what happened.
Martin's mother Sybrina Fulton, who plans to attend every day of the trial, knows that the 911 call along with much the testimony may be difficult to bear.
"I pray for me to forgive," she said in an interview. "I don't want to block my blessing…The verdict in the trial will give us some type of closure, so we are looking forward to the trial."