Synchronization plays an essential role in cooperative performance of music such as orchestra or chorus.Tones of the musical instruments or pitches of the singing voices should be entrained in such a way that they create a nice harmony, where harmonic sounds should satisfy rational frequency relationship (e.g., 3:2 for perfect fifth).If sounds of the music players are not synchronized, their cooperative performance should not be impressive.On the other hand, if a perfect synchronization is achieved, such performance may sound as machinery (computer-generated music), and should be less artistic.Truly artistic music play may lie between such two extreme situations.