In this presentation we show you the application of multidimensional system theory to string models for the simulation of acoustical instruments. We present the extension from the solution of one-dimensional systems described by ordinary differential equations to multidimensional systems described by partial differential equations.. These systems describe e.g. time and space dependent physical phenomena. They are solved here with functional transformations to obtain a multidimensional transfer function model. After inverse transformations and discretization of the transfer function model this method leads to an efficient implementation algorithm for the simulation of the underlying partial differential equation. We show this method on the example of a transversal vibrating string but it is not only restricted to digital sound synthesis but it can also be used for electro-magnetics, optics, acoustics, and heat and mass transfer.