NEW YORK — “Focus on the sound of the instrument,” Mr Andrew Rossetti, a licensed music therapist and researcher, said as he strummed hypnotic chords on a Spanish-style classical guitar. “Close your eyes. Think of a place where you feel safe and comfortable.”

Music therapy was the last thing that Ms Julia Justo, a graphic artist who immigrated to New York from Argentina, expected when she went to Mount Sinai Beth Israel Union Square Clinic for treatment for cancer in 2016. But it quickly calmed her fears about the radiation therapy she needed to go through. The fears were causing her severe anxiety.