A Tutorial on Non-Linear Distortion or Waveshaping Synthesis
Curtis Roads · Computer Music Journal · 1979
In recent issues of Computer Music Journal there have been a number of references to a technique of sound synthesis which is variously termed non-linear distortion, non-linear processing, or waveshaping. This technique has begun to surface as an economical and flexible method of sound synthesis, capable of generating sounds as rich as those produced through computationally costly additive synthesis techniques. In addition, the technique offers a unified theoretical framework for the understanding of several other nonlinear synthesis methods, notably frequency modulation and discrete summation synthesis. The terms non-linear and have yet to be explained in these pages, and with the recent public availability of three major technical papers on the subject (Arfib : 1978; Beauchamp : 1979; and Le Brun : 1979) the need for a tutorial here is made more timely. Although a precise and comprehensive formulation of the results of the various forms of non -linear distortion or waveshaping involve a great deal of calculation, the concepts underlying the technique can be presented in a straightforward, largely nonmathematical form. This brief tutorial is intended particularly as an orientation and a pointer to the more technical papers cited above. Hopefully, a musician unfamiliar with signal processing tools save for electronic music equipment and a MUSIC V-like (Mathews : 1969) graphic patching language will be able to understand the basic concepts of this powerful technique through this exposition. Of course, as Le Brun (1979) points out, research into aspects of nonlinear distortion or waveshaping is continuing, and hopefully, future Computer Music Journal articles will cover these developments in a timely manner.