Abstract

Speech production has long been viewed as a linear filtering process, as described by Fant in the late 1950's [10]. The vocal tract, which acts as the filter, is the primary focus of most speech work. This thesis develops a method for estimating the source of speech, the glottal flow derivative. Models are proposed for the coarse and fine structure of the glottal flow derivative, accounting for nonlinear source-filter interaction, and techniques are developed for estimating the parameters of these models. The importance of the source is demonstrated through speaker identification experiments. The glottal flow derivative waveform is estimated from the speech signal by inverse filtering the speech with a vocal tract estimate obtained during the glottal closed phase. The closed phase is determined through a sliding covariance analysis with a very short time window and a one sample shift. This allows calculation of formant motion within each pitch period predicted by Ananthapadmanabha and Fant to be a result of nonlinear source-filter interaction during the glottal open phase [1]. By