Besides skills in musical expression, exact timing among music players is required in excellent performances. In order to synchronize each respective sound of music among players, they must use a variety of information. In case of four-hand performances on the piano or performances by a band, for example, information such as musical sounds, body movements and gazes is considered to play critical roles. In this study, we empirically investigated roles of the information as communication channels between music players. We conducted an experiment where pairs of players performed music with a constant tempo, one varying its tempo and one including a long rest on the piano. They played the three sets of music both in a face-to-face setting where they could watch each other and a back-to-back setting where they could not. According to the results of the experiment, we then proposed communication models of players in music performances.