Evelyn then shoots it with the shotgun right through its vulnerable, armor-less membrane. All the monster's armor folds back, making him vulnerable to an attack. This causes the monster pain and confusion, so he loses his defenses. She pulls off the hearing aid and puts it through her father's microphone. She realizes that the high frequency of her failing hearing aid is what causes the monster harm. Regan also gets to see her father's control room for the first time, and she begins to put some of his clues together. Regan's hearing aid starts to malfunction again and the monster recoils because of it. They begin to mourn Lee but the baby's cries alert the Quiet Place’s monster to their whereabouts. Regan, Marcus, Evelyn, and the new baby all make it to the control room. He tells his children that he loves them right before he dies, which they witness in person and Evelyn sees through the security cameras. The monster once again gets close to Evelyn and the new baby, but she escapes, and the monster tries to kill Regan and Marcus, but Lee screams to sacrifice himself.
The rest of the final minutes of A Quiet Place involves each member of the family having their own close calls with the monster. It sends off feedback that hurts Regan and causes harm to the monster, but Regan is unaware of its effects on the monster because she isn't facing it when it nearly attacks her. However, the monster almost kills Regan, but the hearing aid that Lee created for her continues to malfunction. The two children eventually find each other in the cornfield.