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SpectrumWorx Manual

Modules: Phase Vocoder

All of these are special versions of modules that also appear in other categories. However, Phase Vocoder modules operate differently under the hood.

“PV” stands for “Phase Vocoder”, but you should not confuse this with the familiar sort of “robot voice” vocoder — though it should be obvious that SpectrumWorx can provide all manner of robotic voices. Normally, SpectrumWorx draws upon Fourier transform algorithms to work its magic in the frequency domain. The Fourier transform is used to transform time samples to the frequency domain, so we end up with various amplitudes and phases of the resulting sine waves — but the sine waves produced by the Fourier transform are only approximations; they don’t represent the “true” frequencies present in the input signal.

Phase vocoding, on the other hand, can be used to find the true frequencies. After the true frequencies are found, we can manipulate amplitudes and frequencies rather than simply amplitudes and phases. This opens up new territory for effects processing. For example, accurate pitch shifting is possible since we know the true frequencies.

To PV and From PV

Section titled “To PV and From PV”

To PV and From PV are the pair of modules that enter and leave the phase vocoder domain. Modules placed between them in the bank operate on true frequencies rather than on magnitude and phase.

The variants

Section titled “The variants”

The remaining seven modules are the phase vocoder versions of modules documented elsewhere in this manual. Their controls are the same, so those descriptions are not repeated here:

Many modules that are not designed to work in the phase vocoder domain can provide some surprising results when used in it, so experiment — but proceed with caution!