ABSTRACT
This chapter describes modal synthesis and explains the physical motivation behind it. It discusses the construction of excitation signals to the modal models for a number of applications. The modal synthesis model is physically well motivated, as the linear partial differential equation for a vibrating system, with appropriate boundary conditions, has as solutions a superposition of vibration modes. An important ingredient in synthesizing realistic scraping and rolling sounds is a surface interaction model. A lot of research has been conducted on models of contact interactions between solids, but they usually focus on predicting forces at a coarser time scale than needed for our purposes, though not all. When a solid object is struck or scraped, or engages in other external interactions, the forces at the contact point causes deformations to propagate through the body, causing its outer surfaces to vibrate and emit sound waves.
