Glitch-free frequency modulation synthesis of sounds

A non-transitory computer readable storage medium storing one or more programs configured for execution by one or more processors of a computer-based sound synthesizer system, the one or more programs comprising instructions to:

• generate a master phase signal, wherein the master phase signal varies in time at a modulation frequency;
• and
• generate 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;
• and
• generating 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.

A computer-based sound synthesizer system comprising:

• one or more processors;
• memory storing one or more programs that, when executed by the one or more processors, cause the synthesizer system to:
• generate a master phase signal, wherein the master phase signal varies in time at a modulation frequency;
• and
• generate 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;
• and
• generating 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.

An apparatus, comprising:

• a master phase generator that generates a master phase signal, wherein the master phase signal varies in time at a modulation frequency;
• and
• a formant generator that generates 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;
• and
• generating 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.