Passive nonlinear filter for digital musical sound synthesizer and method

Abstract

A music synthesizer includes main resonator, such as a digital waveguide network, that is coupled to a digital passive nonlinear filter. The passive nonlinear filter receives traveling wave signals from the resonator and generates modified traveling wave signals having a different frequency spectrum than the received traveling wave signals without changing the received traveling wave signals' energy content. The passive nonlinear filter then transmits the modified traveling wave signals back into the resonator. The passive nonlinear filter includes a first memory element for retaining an internal energy state and a dual-mode signal generator that generates the modified traveling wave signal from the received signals and the internal energy state using a first signal processing method when the internal energy state has a negative value and using a second distinct signal processing method when the internal energy state has a positive value. The dual-mode signal generator preferably includes a two-level amplifier that multiplies the internal energy state by a first coefficient when the internal energy state has a negative value and by a second distinct coefficient when the internal energy state has a positive value so as to generate an adjustment signal. A first signal combiner combines the received signals with the adjustment signal so as to generate a next value of the internal energy state, and a second signal combiner combines the adjustment signal and the retained internal energy state to generate the modified traveling wave signal that is transmitted into the resonator.

Dependencies are inferred from the claim text.