The important psychological basis that determines the aesthetic value judgment of music is: the psychological law of expectation. Music realizes the expression of objects other than hearing through synesthetic correspondence. The clarity of the object of musical expression depends on the persistence and stability of the synesthetic correspondence (see "Music and the World of Expression", Zhou Haihong, Central Conservatory of Music Press, 2004). When the sound of music forms a continuous and stable synaesthetic correspondence with a certain object, it is possible to arouse associations with this object in the listener's mind, thereby stimulating the involvement of more complex experiences and concepts. This deepens the content of musical expression. Therefore, the depth of musical expression is related to the complexity of the associations it evokes. Popular music is not only simple in form, but also because its core pursuit of aesthetic function is to give people pure auditory sensory pleasure and a good and relaxed mood. Therefore, at the beginning of the creation of the work, there is no deliberate pursuit of a good synesthetic correspondence between the organizational arrangement of the music and some external objects. As a result, the synesthetic response caused by such sounds cannot fully arouse the listener's associations. This determines that it is difficult for popular music to produce deep content understanding activities. On the contrary, from the original intention of creation, the aesthetic purpose of many "elegant music" works is not to bring sensory pleasure to people's hearing, but to express human beings' deeper inner feelings and profound understanding of life and the world. Such works often lack the pleasure of auditory senses intuitively. They give people a richer and more diverse perceptual experience, which may include strong stimulation, emotional catharsis, or deep emotional experience. Due to the need to express content, the synaesthetic reactions caused by the sound of such musical works are often more likely to cause sufficient associative activities, thus enabling people to have in-depth content understanding activities of the works. Of course, not all "elegant music" has profound ideological connotations and deep emotional expressions, but we can say that, generally speaking, it brings more such content to people than popular music. Expressive experience. This is the difference in performance content between the two.