An analysis and synthesis technique is described for the estimation and modeling of a particular class of nonlinear acoustical systems with energy-preserving nonlinearities. It is situated in the field of nonlinear sound synthesis techniques. The rich mathematical structure behind the technique is explored, with particular attention to the effects of scaling to arbitrarily high-dimensional systems. The technique is then applied to simulations and recordings of nonlinear vibratory behavior. After estimating model parameters from the timeseries, the models are validated using various assessment techniques, including resynthesis. Applications to computer music are discussed.