Non-Linear Contact Sound Synthesis for Real-Time Audio-Visual Applications using Modal Textures

Sound design is an integral part of making a virtual environment come to life. Spatialization is important to the
perceptual localization of sounds, while the quality determines how well virtual objects come to life. The implementation of pre-recorded audio for physical interactions
in virtual environments often requires a vast library of audio files to distinguish each interaction from the other.
This paper explains the implementation of a modal synthesis toolkit for the Unity game engine to automatically
add impact and rolling sounds to interacting objects. Position-dependent sounds are achieved using a custom shader
that can contain textures with modal weighting parameters.
The two types of contact sounds are synthesized using a
mechanical oscillator describing a mass-spring system. We
describe the discretization methods adopted, the solution
of the nonlinear interaction and an implementation in the
Unity game engine.