Robert Romero planned to spend his 52nd birthday on a fishing trip. Instead, the Anaheim resident was laid up in a hospital bed, recovering from surgery to remove a tumor on his kidney that doctors had discovered by chance.

Romero’s wife was secretly scrambling to have balloons and a cake brought to his room at St. Joseph Hospital in Orange. Then came a surprise she didn’t plan.

Robert Stone walked in carrying a curved case, its leather rubbed bare. He pulled a 73-year-old German violin from the green velvet lining, settled the instrument under his chin, and raised the brown bow.

Out came a soft but upbeat rendition of “Happy Birthday,” which Stone shared a day before his own 76th birthday.

“That is therapeutic,” Romero said, smiling as he thanked this stranger, who shared his first name and nearly shared his birthday. “You could definitely see the advantage of that.”

At least once a week, Stone spends a couple of hours wandering the halls at St. Joseph, looking for an audience.

Sometimes he’ll be in the surgery ward, sometimes in oncology. Whenever he sees a patient awake, he’ll knock gently on the open door and ask if he can play a song for them, taking requests for everything from worship songs to show tunes.

Stone started the tradition three years ago. He’d read an article about music therapy, with a growing body of research that shows music can help reduce anxiety, manage pain, improve moods, and speed recovery for patients.

“Most of us know that music speaks to the mind, emotions, and spirit in ways that sometimes words and visual images cannot,” said Johanna Shapiro, director of Medical Humanities & Arts at UC Irvine. “Increasingly, physicians recognize the potential of music to contribute to the healing of patients and choose to incorporate music therapy into patients’ treatment plans.”

Stone retired from working in the senior care industry and was looking for a way to give back through music. He’d been impressed with St. Joseph when he’d visited friends there in the past. When he called, he learned the hospital’s previous music therapist—a harpist—was no longer there. So Stone took the gig.

Putting the audience to sleep isn’t most musicians’ goal. But during Stone’s first tour at St. Joseph, he stopped to play the Irish ballad “Danny Boy” for an elderly patient. He noticed the woman close her eyes, which patients often do as they take in the music. Then one of the nurses peeked into the room.

“The nurse said, ‘I think she’s asleep,’” Stone recalled. “‘We’ve been trying to get her to sleep for days.’”

Most of the time, he said, his playing has the opposite effect. “People cheer up,” he said. “They just come to life.”

One elderly Latino woman had been a stoic patient, lying quietly without complaint. As Stone played “La Cucaracha,” the woman began to sway in her bed. Her son said it was the first time he’d seen her smile in a few days.

A 94-year-old patient who was nearing the end of her life asked for gospel hymns in honor of her husband, who’d been a pastor until his death a decade earlier. The woman started to sing along as Stone played, tears streaming down her weathered cheeks.

Stone first played for Theresa Ballard, 58, during her hospital stay in March 2014. When the Santa Ana resident had to come back for an abdominal hernia and stay through Christmas, Ballard said she was relieved to see Stone walk in wearing his navy blue hospital volunteer shirt and carrying his worn leather case.

“He was just an absolute breath of fresh air and made everything so much more bearable,” Ballard said.

She was back at St. Joseph on a recent Monday with a fever and some complications from her Christmastime surgery.

Ballard closed her eyes and hummed along as Stone played “Somewhere Over the Rainbow” and “Amazing Grace.”

“You can feel his heart in the music,” she said.

Stone took up the violin when he was 9, inspired by solos he heard during radio programs such as “The Voice of Firestone.”

He was 10 or 11 when he got his first request. His dad wanted to hear “Tennessee Waltz,” so Stone learned to play the country standard.

Stone started taking lessons in school. He took private lessons until he was 18, always relying on a mixture of reading music and the ability to play by ear.

He regularly performs today with the Tustin-based Praise Symphony Orchestra and at his Santa Ana church. And the grandfather is now teaching himself to play the classical guitar.

That instrument might have lent itself more easily to accommodating the rare request he got from St. Joseph patient Gaston Bastanchury of Garden Grove: country western music.

Stone dug deep into his repertoire, pulling out the theme from “Bonanza” and Roy Rogers’ “Don’t Fence Me In.” A man walking down the hall took notice, whistling along as he passed.

Then Bastanchury asked for some Johnny Cash. Stone thought for a moment, then played “Folsom Prison Blues” for the first time. And 79-year-old Bastanchury beamed.

A song is a simple thing, Ballard acknowledged. But she added, “Sometimes that’s all it takes to make a difference in how you’re feeling.

“If more people volunteered their time like this,” Ballard said, “more people would get healthier a lot faster.”