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B. Barış; "Zeros of the z-transform...", 24.06.2005, 15:00, G032

Zeros of the z-transform (ZZT) representation and chirp group delay processing for analysis of source and filter characteristics of speech signals

Barış Bozkurt
Abstract: This talk presents use of new spectral methods for various speech analysis problems. Two new spectral representations will be introduced: the zeros of z-transform (ZZT) representation and the chirp group delay. The ZZT representation is simply an all-zero representation of the z-transform of a given discrete time signal. It will be shown that a study of the ZZT of speech signals is essential for understanding the sources of difficulties involved in phase/group delay processing of speech signals. We define chirp group delay as group delay calculated on a circle other than the unit circle in z-plane. The need to compute group delay on a circle other than the unit circle comes from the fact that group delay spectra are often very noisy and cannot be easily processed for formant tracking purposes (the reasons are explained through ZZT representation). We propose methods to avoid such problems by modifying the ZZT of a signal and further computing the chirp group delay spectrum. The combination of the ZZT representation with the chirp group delay processing algorithms provides an effective domain to study resonance characteristics of source and filter components of speech.
Following the theoretical discussions, applications in source-tract decomposition of speech, glottal flow parameter estimation, formant tracking and feature extraction for speech recognition will be demonstrated.
 
Bio: Barış Bozkurt graduated as an electrical engineer in 1997 and received an M.S. degree in biomedical engineering in 2000 both from the Boğziçi University/Istanbul, Turkey. He joined the TCTS research team of Faculté Polytechnique de Mons, Belgium in 2000 where he is still continuing his Ph.D. research. His main interests are speech analysis and synthesis.
 
June 24, 2005, 15:00, G032


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