Kaitlin Ashway sits in the pit section of the marching band, nestled between booming timpani drums and a girl playing the electric bass.

No music in hand, she strikes a tambourine as the mood moves her, following the band's upbeat tempo.

"Her face is lit up when she's out there," said her mother, Tamara Ashway. "She gets involved with the music with her whole body. Her chair starts rocking."

Kaitlin, 15, is sophomore at Penn Manor High School.

Before her first birthday, she underwent open-heart surgery for a congenital heart defect.

During the operation, the fragile infant was put on a heart and lung bypass machine.

But something went wrong.

While the machine was meant to deliver blood to her developing brain, pure oxygen invaded the system — leaving her with bilateral brain damage.

"Her neurologist thought she'd be a vegetable, that she would never do anything," Tamara said.

Kaitlin's injuries kept her in the hospital for five weeks, where the pain caused her to cry endlessly.

"I remember thinking that I'm going to be tube-feeding this screaming person for the rest of my life," her mother said.

"So for her to be doing this," she said, as she watched her bubbly teenage daughter's teal-painted fingernails fly through the air, "is something I never imagined."

This season will mark Kaitlin's second year of playing tambourine with the school marching band, drawing her closer to her classmates.

"The innocence of her enjoyment of the music is refreshing," band director Tom Mumma said.

"Kaitlin couldn't be on a sports team. But here, she's part of the ensemble, making music with everybody else."

Since she started playing in the band — using a modified mallet to strike the tambourine — the first thought on Kaitlin's mind every day is music, her mother said.

"Music crosses all barriers," she said.