We now turn to the 3-dimensional version of the wave equation, which can be used to describe a variety of wavelike phenomena, e.g., sound waves and electromagnetic waves. One could derive this version of the wave equation much as we did the one-dimensional version by generalizing our line of coupled oscillators to a 3-dimensional array of oscillators. For many purposes, e.g., modeling propagation of sound, this provides a useful discrete model of a three dimensional solid.
wave equation, oscillator, discrete, chapter 9, nine
Torre, Charles G., "09 The Wave Equation in 3 Dimensions" (2012). Foundations of Wave Phenomena. Book 14.