Arpie is a music making app that turns movements of bouncing balls into musical sequences. The initial motivation of this project is designing an intuitive music making system that can be understood by all audiences, and overcoming the constraints of the contemporary musical notation system.

The idea is simple: everyone — even children and old people — can understand basic physical behaviors such as bouncing ball, and physical behaviors have a sort of regularity in it. This indicate a possibility that an intuitive music system could be implemented on physical behaviors instead of music notations. Arpie is the first deliverable of this idea.

Arpie is available on iTunes App Store and Google Play Store for free, and its source code is provided under the open source license.