听力原文： It is common knowledge that music can have a powerful effect on our emotions. In fact, since 1930s, music therapists have relied on music to soothe patients and help control pain. Now psychologists are confirming that music can also help relieve depression and improve concentration. For instance, in a recent study, 15 surgeons were given some highly stressed math problems to solve. They were divided into three groups: one worked in silence, and in another, the surgeons listened to music of their choice on headphones; the third listened to classic music chosen by the researchers. The results of the study may surprise you. The doctors who got to choose their music experienced less stress and scored better than the others. One possible explanation is that listening to music you like stimulates the Alfa-wave in the brain, increases the heart rate and expands the breathing. That helps to reduce stress and sharpen concentration. Other research suggests a second relation between the music and the brain: by examining the students’ blood after they listening to a variety of classic music collections, the researchers found that some students showed a large increase in endorphin, a natural pain reliever, this supports what music therapists have known for years: Music can help rejuvenate or soothe the patient.
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A. Training given to music therapists.
B. How music prevents disease.
C. studies on the benefits of music.
D. How musicians create music.