This invention provides a signal processing and signal synthesis technique from a family of signal processing and signal synthesis techniques designed to readily interwork or be used individually in creating new forms of rich musical timbres. Synthetic hysteresis waveshaping is used to create naturally appealing dynamic spectral variations from an input signal of varying amplitude and waveshape. Waveshaping curves, waveshaping parameters, hysteresis characteristics and hysteresis parameters may be recalled from stored program control or modulated in real-time by arbitrary control signals, including those derived from the original input signal. The invention may be used individually or in conjunction with other signal processing and signal synthesis techniques in creating new forms of rich musical timbres. The invention may also be used in spatially-distributed timbre construction.