I. Introduction
While music is universally enjoyed by human, it is also widely recognized as an effective way to regulate the emotional states of listeners [1]. The regulation mainly depends on three aspects, namely, the music, the listener, and the listener's perception of the music. First, music emotion is mainly delivered by the three musical elements of melody, rhythm, and harmony. Second, the listener's emotional states are much determined by internal factors such as the physical and spiritual health states of the listener, and greatly influenced by external factors such as the task or activity the listener is involved in. Third, music perception is a very subjective issue, which varies greatly from person to person. One person's trash is another's treasure. The listeners have their own favorite music genres and styles. Moreover, they have unique life experiences and memories.