Using spectral properties of the Laplace operator and some structural formula for rapidly decreasing functions of the Laplace operator, we offer a novel method to derive explicit formulae for solutions to the Cauchy problem for classical wave equation in arbitrary dimensions. Among them are the well-known d'Alembert, Poisson, and Kirchhoff representation formulae in low space dimensions.
Gusein Sh. Guseinov. "Spectral Approach to Derive the Representation Formulae for Solutions of the Wave Equation." J. Appl. Math. 2012 1 - 19, 2012. https://doi.org/10.1155/2012/761248