Pitch Shift Plug-Ins : Time Shift : Time Shift Controls : Time Shift Formant Controls

Time Shift Formant Controls
The Formant section of Time Shift lets you shift the formant shape of the selected audio independently of the fundamental frequency. This is useful for achieving formant correct pitch shifting. It can also be used as an effect. For example, you can formant shift a male vocal up by five semitones and it will take on the characteristics of a female voice.
The Formant section is only available when Monophonic is selected as the Audio Type. The Formant section provides a single control for transposing the formants of the selected audio by –24.00 semitones (–2 octaves) to +24.00 semitones (+2 octaves), with fine resolution in cents. Adjust the Formant Shift control or click the Shift field and type the desired value.
 
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Audio with a fundamental pitch has an overtone series, or set of higher harmonics. The strength of these higher harmonics creates a formant shape, which is apparent if viewed using a spectrum analyzer. The overtone series, or harmonics, have the same spacing related to the pitch and have the same general shape regardless of what the fundamental pitch is. It is this formant shape that gives the audio its overall characteristic sound or timbre. When pitch shifting audio, the formant shape is shifted with the rest of the material, which can result in an unnatural sound. Keeping this shape constant is critical to formant-correct pitch shifting and achieving a natural sounding result.