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