Police Officer Betty Shelby has pled not guilty in the fatal shooting of 40-year-old Terence Crutcher, who was unarmed. The New York Daily News reported Shelby's attorney said Friday that Shelby was temporarily deaf during the shooting. The Tulsa, Okla. officer faces first-degree manslaughter charges.

"Auditory exclusion" is what Shelby’s attorney Scott Wood called the event. "She didn't hear the gunshot, didn't hear the sirens coming up behind her just prior to the shot," Wood said Thursday.

"Auditory exclusion" happens when people in high-pressure situations get tunnel vision and block out the noise of their surroundings. "It's not only a common phenomenon described in literature," said Wood, "but it's the No. 1 perceptual distortion by people I have represented who have been involved in shootings—diminished sound or complete auditory exclusion."

Tulsa County District Attorney Steve Kunzweiler pressed charges against Shelby that led to her arrest Friday. According to the Washington Post, Shelby was released on $50,000 bail after only 20 minutes.

After the charges were announced, Crutcher's family held a press conference in which his twin sister Tiffany spoke, saying the family was happy about the charges: "Our goal now, as a family, is to ensure this never happens to another citizen. We will stay vigilant as this process moves forward and join the other[s] peacefully in demanding greater accountability and transparency from law enforcement."

If convicted Shelby faces life in prison. A hearing is set for Nov. 29.