THE SOUNDS OF PHYSICAL SHAPES

We propose a general framework for the simulation of sounds produced b y colliding physical objects in a virtual reality environment. The fra mework is based on the vibration dynamics of bodies. The computed soun ds depend on the material of the body, its shape, and the location of the contact. This simulation of sounds allows the user to obtain impor tant auditory clues about the objects in the simulation, as well as ab out the locations on the objects of the collisions. Specifically, we s how how to compute (1) the spectral signature of each body (its natura l frequencies), which depends on the material and the shape, (2) the ' 'timbre'' of the vibration (the relative amplitudes of the spectral co mponents) generated by an impulsive force applied to the object at a g rid of locations, (3) the decay rates of the various frequency compone nts that correlate with the type of material, based on its internal fr iction parameter, and finally (4) the mapping of sounds onto the objec t's geometry for real-time rendering of the resulting sound. The frame work has been implemented in a Sonic Explorer program which simulates a room with several objects such as a chair, tables, and rods. After a preprocessing stage, the user can hit the objects at different points to interactively produce realistic sounds.