Shakeela Hassan has told the story so many times, it’s almost like a song: the soft knock on her dorm room door every morning at 5 a.m., from the nuns at St. Mary of Nazareth Hospital on Chicago’s West Side. “Time for Mass, Doctor.” Every day, Hassan, then 23 years old, a Muslim and a newcomer from India, would rise and make her way to the hospital’s chapel. Sharing the pews with patients and their families, she would listen to the nuns chanting in Latin.

She didn’t understand a word, but she was deeply moved. “I didn’t want to breathe or sneeze or cough or make any sound,” Hassan says, that would disturb “the peace of the chapel.” Instead, she prayed. “They were going full blast with the rosaries, and Arabic prayers were resonating in my brain. Because that’s the only way I knew how to pray. And I still have that unbelievable connection I felt from my heart to whatever we pray to, and the deep feeling of community with the nuns in the chapel.”

That was nearly 60 years ago. Born and raised in Hyderabad, India, Hassan had come to the United States with a new medical degree to find work as a physician. After an internship at Northwestern, she was a resident at St. Mary of Nazareth, a Catholic hospital in a Polish enclave of the Ukrainian Village neighborhood. Now a UChicago associate professor emerita and a scholar in the University’s Program on Medicine and Religion, Hassan remembers those mornings in the chapel as the genesis of a lifelong devotion to sacred music, interfaith understanding, and the healing power of sound.

That fascination flowered in 1999, when Hassan retired from practicing medicine. She collaborated on the 2002 PBS documentary Muhammad: Legacy of a Prophet, traveling to 40 states to raise money for the film. In 2009 she coproduced Sounds of Faith, a three-part series exploring the sacred music of Judaism, Christianity, and Islam. She organized a concert by the same name that year at Rockefeller Chapel; in 2014 Rockefeller hosted a five-year anniversary Sounds of Faith concert, adding Hindu and Buddhist music to the program.

During the concert’s opening song, Muslim calls to prayer mingled with the blast of a Jewish shofar and the drone of the chapel’s organ. Rockefeller dean Elizabeth Davenport played a set of Tibetan singing bowls while singers chanted the Hindu peace mantra, “Om shanti.” There were chanted recitations from the Quran and the Hebrew bible, a performance of “Ave Maria.” The Rockefeller children’s choir sang on the chancel steps, and the UChicago Russian choir Golosá sang from a rear balcony. Hassan sat in the first pew in a shimmering green sari.

The years Hassan has spent promoting interfaith compassion and “the idea that sacred sound connects us to God and to one another” have also seen profound sectarian conflict across the globe: war, terrorism, religious prejudice. “I have been quite disturbed at how civilized we are and how uncivil we are at the same time,” Hassan says. Disturbed, but not deterred. With her nonprofit, Harran Productions Foundation, she has traveled around Chicago, the United States, and the Middle East, organizing concerts and presentations at schools and religious centers, aimed at fostering interreligious understanding through music and sound. In 2014 she recorded a TEDx talk about how “sound, rhythm, and movement” define and unify human life.

To Hassan, “sound,” including sacred sound, doesn’t only mean music. As an anesthesiologist, she says, she was struck by the fundamental human importance of sound. Hearing is the most developed of the senses at birth. In patients under anesthesia, it’s the last sense to go as they lose consciousness and the first one they regain. (“I always said to my residents: ‘No jokes permitted. The patient can hear you.’”) During operations, she kept wordless watch over her patients, listening to the ventilator sound of their breathing and the electrocardiograph beep of their heartbeat. “That’s sound, rhythm, and movement,” she says. In medical school, “they were taught like this: inspection, palpation, percussion, auscultation.”

Paraphrasing Divinity School professor Michael Sells, AM’77, PhD’82, from the Sounds of Faith documentary, Hassan compares sound to water: it goes into the deepest crevices, becomes part of everything. She abstracts further. “What is symphony?” she says. “Why do we go to the seaside and sit down beside the ocean? Why do people go for a walk?” For the sound, she says, which is present even in silence. “How you come to peace with it is by becoming a part of it.” In the chapel pews at St. Mary of Nazareth Hospital so long ago, that’s what Hassan did.