Artist Statement

Resonating rotation of a rigid body, is a sonic apparatus that works by the interaction of frequency, vibration and phisic property of materials. A rigid body was left standing on a vibrating plate at given frequency. A modified speaker is joint to that plate and works as a vibrating driver to produce the appropriate frequency to generate vibrations in the body that start to rotate around its vertical symmetry axis at a corresponding frequency.
Despite the apparent simplicity of this device, the physical mechanism behind their dynamics is subtle and complex. The conversion from vibrating to rotating energy is mediated by an asymmetric friction against the ground, and by elastic energy temporarily stored in the body. In fact, in order to make the body rotate, it is essential that the body is bent to one side when lying to the vibrating plate. The unbalanced distribution of its mass allows to release the inner tension caused by vibrations in a way wich enables the body to rotate.
Rotation depends on the shape of the body and on the amount and distribution of its mass. There is rotation only at certain frequencies or frequency ranges when the body start to resonates. As could be intuitively expected, the rotation frequency increases as the shaking amplitude is increased, anyway after a certain value the angular velocity decays as the vibration frequency increases.
Between the strip and the panel emerge a variable tensional state. That variations is generated by the movement of the body wich spreads its weight in different places during the rotation. Thus, the body during a complete round assumes different vibrational state, and then different speed and noise, wich repeats its cycle in each round.
The percived sound is the addition of the original audio input (a flat sine/square wave) and the sound produced by the body during its rotation. The sound generated by that process can be defined as non-deterministic. If I slightly change bending the strips or I just move them few millimeters, their conduct will be different and the sound will be different. For that reason is impossible to repeat exactly the same performance in different sessions.
The outcome of my performance is either acustic and visual. The sound is manipulated in such a way as to generate the necessary energy to produce the restraint/sculptural movement of the bodies and produce a sense of beauty that involves the study of matter and its motion along with related concepts such as energy and force.
creativeapplications.net/sound/resonating-rotation-of-a-rigid-body-matteo-crivella/

References:
Vibrot, a Simple Device for the Conversion of Vibration into Rotation Mediated by Friction: Preliminary Evaluation
Ernesto Altshuler, Jose Martin Pastor, Angel Garcimartin, Iker Zuriguel, Diego Maza Published: August 5, 2013D01: 10.1371/journal.pone.0067838

• Matteo Crivella is a sound designer from Milan, Italy