This book discusses the physics of vibrating systems, emphasizing mechanics rather than electrodynamics. Beginning with the basics of free and forced motions of a simple harmonic oscillator (both mechanical and electrical) it goes on to discuss vibrations in one-dimensional systems, such as strings and bars, and two-dimensional systems such as membranes and plates. The discussion of coupled systems includes strong as well as weak coupling, and presents both mechanical and electrical examples. The analysis includes nonlinear systems, dispersion, and other topics. The concluding third of the book discusses the propagation of sound in air; the radiation from various sources (points, planes, lines, baffled planes, and so forth); and the propagation of sound in various kinds and shapes of pipes.