A lovely demo by MIT researchers Xiao Xiao and Hiroshi Ishi of Andante, a system for interactive music learning:
Andante visualizes as animated characters walking along the piano keyboard that appear to play the physical keys with each step. Based on a view of music pedagogy that emphasizes expressive, full-body communication early in the learning process, Andante promotes an understanding of the music rooted in the body, taking advantage of walking as one of the most fundamental human rhythms.
More in their research papers (PDF):
• Andante: Walking Figures on the Piano Keyboard to Visualize Musical Motion (NIME 2014)
• Inspect, Embody, Invent: A Design Framework for Music Learning and Beyond (CHI 2016)