New ensemble system based on mutual entrainment

Mutual interaction of rhythm is widely observed in the ensemble between humans. However, one-sided action is dominant in the interaction between human and musical machine. Thus, in this research, we try to realize human-like ensemble system by using mutual interaction between rhythms. To realize such a communication between human and machine, we used entrainment model of rhythms, and mutual entrainment is regarded as a mutual interaction, and as a control condition forced entrainment is used to realize one-sided action. Comparing these models, differences between one-directional and bi-directional communication are clarified, and effectiveness of our mutual entrainment based ensemble system is shown. Our system is constructed as cooperation between human player and MIDI application designed on Windows. In this system, human plays MIDI keyboard and its signal is transmitted to MIDI application. On the other hand, the sound signal from MIDI application is transmitted to human by using speaker. Experiments using this system show that the mutual entrainment based model can achieve much better performance than that based on forced entrainment model. This is due to a flexible coordination and stability of its cooperative performance, in other words, not only the phase difference between human rhythm and MIDI application was decreased, but also the fluctuation of it was also decreased. From these results, it was indicated that mutual entrainment based bi-directional communication is effective and essential to realize human-like ensemble