Automatic tracking of speech parameters for parallel formant synthesis

A speech synthesis model in which the formant resonators are connected in series does not produce satisfactory speech quality for sounds produced with a narrow constriction in the vocal tract or with the velum lowered so that the nasal cavity is coupled to the oral cavity. These latter cases are better handled by a parallel connection of formants, in which the amplitudes of the individual formants can be controlled independently. An existing analysis-synthesis method for a series model of speech [J.P. Olive, “Automatic Formant Tracking by a Newton-Raphson Technique,” J. Acoust. Soc. Am. 50, 661–670 (1971)] has been adapted to a parallel formant model of speech. The analysis procedure derives pitch and four formant frequencies and amplitudes from natural speech which are then used to control a speech synthesizer. The quality of synthetic speech produced in this manner is a substantial improvement over that produced according to a series model.