Yuan Yuan and Zhang Xiaosong are teachers and students. Yuanyuan overheard a voice when she was in college. This is the sound of Zhang Xiaosong playing the blues harmonica. With the mentality of giving it a try, Yuanyuan carefully asked Zhang Xiaosong for advice in a private letter. I didn't expect Zhang Xiaosong to write back soon. Become a netizen once and for all. Later, under the teacher's demonstration, Yuanyuan formally joined the blues harmonica network, and recorded a set of teaching called Garden Harmonica Classroom under the leadership of Zhang Xiaosong.