Basic Differential Equations . No approximations or assumptions are made beyond those made in defining the model itself. Small-signal approximations are made to derive the acoustic and wave equations from the above differential equations. Plane Waves . The general plane wave solutions to the sound wave equations are analyzed.
Sound created by a piston vibrating harmonically in a tube is analyzed.
Coupling Power out of a Plane Wave . The reception of power from a sound wave is analyzed. Conditions for total power absorption by a piston are determined. An elementary spherical wave solution is presented. A more detailed description is given in the subsection on plane and spherical wave spectra .