Method and apparatus for synthesizing musical sounds by freq uency modulation using a filter

摘要

This invention provides a circuit for synthesizing musical sounds. In one embodiment, the circuit includes a first order FIR highpass filter that is placed between a modulation phase increment oscillator and a carrier phase increment oscillator. The invention may also include waveshaping circuits, adders, multipliers, time division multiplexing, and other types of filters. Another embodiment of the invention provides a music synthesis method where a modulation phase increment is multiplied by a modulation index to produce a modulation signal. That modulation signal is then filtered and added to a carrier phase increment. Finally, that sum is multiplied by an amplitude envelope to produce a signal representing a musical sound. The method may include using a first order FIR highpass filter, waveshaping of both sinusoidal and non-sinusoidal waveforms, additional multiplying and time division multiplexing. The invention also includes self-modulation and cascading.