A study of the variation of glottal pulse shape with fundamental frequency by inverse filtering of the speech wave
Arthur P. Lobo, William A. Ainsworth · The Journal of the Acoustical Society of America · 1990
The acoustics of speech production is based on the concept of a source and a filter function. In current models the source of voiced sounds is represented by a quasiperiodic succession of pulses of air emitted through the glottis, as the vocal cords open and close, and the filter function is assumed to be linear and short-time invariant. The source term or the acoustic excitation produced by the larynx is subject to variation in speech produced by a natural speaker. The analysis described here forms part of an investigation into variation of the shape of the glottal volume velocity waveform as a function of fundamental frequency. The deconvolution of the speech wave, i.e., separation of the glottal pulse signal from the vocal tract impulse response, is done by inverse filtering the speech signal using a filter derived in the closed phase of the glottal cycle. Linear predictive covariance analysis is used in estimating the inverse filter coefficients. A linear relationship between the glottal parameters, open phase, opening duration, and closing duration with time period is shown. A model is then proposed for the variation of these glottal parameters with fundamental frequency.