In ensemble performances, players can understand how their co-players perform by practicing with them. This study aimed to clarify whether the relationships built between players during practice time correspond to their relationships between players that appear in their way they match the actual performances and in the sounds of the performances. We conducted ensemble experiments involving ten violinists and four cellists, and evaluation experiments involving two violin instructors and three cello instructors. In the ensemble experiments, we analyzed the practice time and eight actual performances. We examined the role in practice progress, relationship adjustment based on attribution of causes and indication of evaluation, role in the actual performances, and impressions given by performance sounds. The findings show that players’ relationships were generally consistent with the relationship between players in ensembles, such as the role in the actual performances and the impressions given by the performance sounds. These results indicate that the factors that influence the performance of ensembles include democratic leadership by the facilitator during practice time, communication during the actual performances based on the interpretations shared during practice, and the role of the practice facilitator in coordinating the performance.
