Low-level sound models: resonators, interactions, surface textures

The design approach outlined in this chapter can be roughly referred to as low-level modeling. The basic physical mechanisms involved in sound generation are accounted for, including the description of resonating structures, as well as various interaction modalities, such as impact and continuous contact (friction). Section 8.2 describes an efficient structure for describing resonating objects, based on the modal analysis/synthesis approach. Section 8.3 presents models for the non-linear interaction forces which arise during collision and friction between two modal resonators, and describes an efficient model for rendering texture of surfaces with variable degree of roughness. Section 8.4 discusses the implementation of these contact models as real-time modules, and addresses the problem of control. Finally, details about the synthesis algorithms are given in the appendix 8.A. This is especially meant to help the understanding of the numerical techniques used for developing real-time algorithms, and provides detailed equations and pseudo-code. Chapter 9 will make use of these sound models for developing high-level strategies for sound presentation.