Formant extraction from group delay function
B. Yegnanaryana, G. Duncan, Hema A. Murthy · 1988
A new approach to the extraction of formant information from speech signals is presented. The method exploits the additive and high resolution properties of group delay functions to resolve even closely spaced formants. The group delay function (or the negative derivative of Fourier transform phase) is derived for a minimum phase signal, which in turn is derived from the Fourier transform magnitude of the speech signal. The method is shown to give highly consistent estimation of formants without resorting to any modelling approach for smoothing the magnitude spectrum.