Musical piano performance by the ACT Hand

In the past, the music community conducted research on what makes music more musical or expressive. Much of this work has focused on the manipulation of phrasing, articulation and rubato to make music more expressive. However, it has been difficult to study neuromuscular control used by experts to create such musical music. This paper took a first step toward this effort by using the Anatomically Correct Testbed (ACT) Robotic Hand to mimic the way expert humans play when they are instructed to perform "musically" or "robotically." Results from 22 human subjects showed that musical expression contained a larger range of dynamics and different articulation than robotic expression, while there was no difference in the use of rubato. The ACT Hand was controlled to the level of precision that allowed the replication of expert expressive performance. Its performance was then rated by 17 human listeners against music played by a human expert to show that the ACT Hand could play as musically as an expert human. Furthermore, articulation, phrasing, and rubato were tested in isolation to determine the importance of articulation over phrasing and rubato. This type of study will lead to understanding how to implement future robots to perform musically without pre-programming them, finding ways to teach novice pianists strategies in controlling their muscles to become expressive musicians more quickly, and understanding why humans feel expressiveness or even emotion in music.