Physical Acoustics: Principles and Methods, Volume XV is a four-chapter text that covers the history of ultrasonics, interdigital transducers, theory of resonance scattering, and acoustic emission. Chapter 1 provides the history of ultrasonics and the developments of its application in crystal transducers, oscillators, selective wave filters, underwater sound, dentistry, and medicine. Chapter 2 is a comprehensive account of the use of circuit model analysis to design interdigital transducers (IDTs) for surface acoustic wave (SAW) devices. This chapter also looks into the total filter design problem for the important case of SAW filters composed solely of IDTs and matching circuits. Chapter 3 discusses the resonance scattering theory, its application to acoustic-and elastic-wave scattering, and the relevant experiments. Chapter 4 deals with the optical detection of acoustic emissions, acoustic emissions during various transformations, and dislocation effects. Researchers in the fields of electronics technology and applied and engineering mechanics will find this book invaluable.