This app is an audio-visual synthetizer based on harmonic motion, it enables to explore a physical simulation of pendulum oscillations through random motion, beating, travelling waves or standing waves are at the tips of your finger.Parameters of the simulation such as synchronisation or travelling speed are tweakable. Sound parameters will enable you to explore several harmonic mapping from consonant to most 'bizarre' ones.
It can be used for interesting recordings and it is for free.
Will also mention that the developer also have a older application that I never mentioned called
Springsv3 and Springs that is possible to see in action after the Phase Pendulum video.