This book provides an in-depth study of the foundations of statistical energy analysis, with a focus on examining the statistical theory of sound and vibration. In the modal approach, an introduction to random vibration with application to complex systems having a large number of modes is provided. For the wave approach, the phenomena of propagation, group speed, and energy transport are extensively discussed. Particular emphasis is given to the emergence of the diffuse field, the central concept of the theory. All important notions are gradually introduced---making the text...