What do you mean by sihui?

Four will refer to the Quartet Music Club. Selected Works of Song Yu: "The thin strips are sad, the sound is like rustling, the turbidity is harmony, and the five changes will be four." Shan Li's note: "Four meetings, four hanging meetings. Youyun: the joy of meeting the instrument. " Yu Xin of the Northern Zhou Dynasty wrote "Taoist stepping on empty words": "I heard about four meetings and suddenly suffered three disasters."

It can also be understood as a birthday song without lyrics played only by musical instruments in ancient times.