Estimation of Vocal Fold Characteristics using a Parametric Source Model

We describe a new method to estimate vocal cord dynamics using a parametric model of glottis movements in order to assess the health of the vocal cords and detect pathological conditions of the larynx. The underlying model is based on that proposed by the Fujisaki-Ljungqvist, modified by reducing the number of parameters. The choice of a parametric model enabled us to assess the impact of the various model characteristics as well as the number of parameters. In the first step of the process we estimated the transfer function of the vocal tract and used it to approximate the model-generated speech. The general approach to the vocal tract estimation was based on the hypothesis that the vocal tract filtering action and the glottal forcing functions affect different, non-overlapping, frequency bands, and can therefore, be separated by homomorphic filtering. In the second step we used filtering of the acoustic waveform, using the estimated vocal tract transfer function H(ω) to estimate the shape of the glottal pulses. The actual estimates of H(ω) were obtained by applying an inverse filtering approach, using the cepstral method in conjunction wit