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In page Physical modelling synthesis:

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Although physical modelling was not a new concept in acoustics and synthesis, having been implemented using finite difference approximations of the wave equation by Hiller and Ruiz in 1971[citation needed], it was not until the development of the Karplus-Strong algorithm, the subsequent refinement and generalization of the algorithm into the extremely efficient digital waveguide synthesis by Julius O. Smith III and others,[citation needed] and the increase in DSP power in the late 1980s[2] that commercial implementations became feasible.