Glitch-Free Frequency Modulation Synthesis of Sounds

摘要

A time-varying formant is generated at a formant frequency by generating first and second harmonic phase signals having first and second harmonic numbers, respectively, in relation to a modulation frequency. The first and second harmonic phase signals are generated in proportion to a master phase signal, which varies at the modulation frequency, modulo a factor corresponding to their harmonic numbers. First and second sound signals, based on the first and second harmonic phase signals, are frequency modulated to create an arbitrarily rich harmonic spectrum, depending on an FM index. The time-varying formant is generated by generating a time-varying combination of the first and second harmonic sound signals, weighting the first and second harmonic sound signals in accordance with their spectral proximities to the formant frequency. One or more of the harmonic numbers are updated when the time-varying formant frequency passes the frequency of either sound signal.

主权项

1. A method of synthesizing sound, comprising:
at a computer-based sound synthesizer system including one or more processors and memory storing programs for execution by the processors:
generating a master phase signal, wherein the master phase signal varies in time at a modulation frequency; andgenerating one or more time-varying formants, each at a respective time-varying formant frequency, wherein generating each time-varying formant comprises:
generating a first harmonic phase signal having a first harmonic number in relation to the modulation frequency, wherein the first harmonic phase signal is generated in proportion to the master phase signal modulo a factor corresponding to the first harmonic number;generating a first harmonic sound signal based on the first harmonic phase signal, wherein the first harmonic sound signal has a spectral peak centered substantially at a frequency of the first harmonic phase signal;generating a second harmonic phase signal having a second harmonic number in relation to the modulation frequency, wherein the second harmonic phase signal is generated in proportion to the master phase signal modulo a factor corresponding to the second harmonic number;generating a second harmonic sound signal based on the second harmonic phase signal, wherein the second harmonic sound signal has a spectral peak substantially at a frequency of the second harmonic phase signal; andgenerating the time-varying formant at the time-varying formant frequency by generating a time-varying combination of the first harmonic sound signal and the second harmonic sound signal, wherein the combination weights the first harmonic sound signal in accordance with a spectral proximity of the frequency the first harmonic phase signal to the formant frequency, and weights the second harmonic sound signal in accordance with a spectral proximity of the frequency of the second harmonic phase signal to the formant frequency.