Speech production modelling with variable glottal reflection coefficient

Recognition and synthesis of speech require accurate models of speech production. Inherent in linear predictive modelling is the assumption that the formant frequencies and bandwidths of speech do not change within the analysis frame-usually at least a larynx cycle. It is shown that there can be significant differences in formant characteristics between the closed and open glottis phases of the larynx cycle. A development of the lossless tube model is presented in which the formant variations between closed and open glottis phases are modelled by a time varying glottal reflection coefficient. A numerically based method for estimating the parameters of such a model is outlined. The results of analysis and re-synthesis of female voiced speech obtained using this model are compared to those obtained using conventional LPC