Voice Quality

Offers a new model of vocal tract articulation that explains laryngeal and oral voice quality, both auditorily and visually, through language examples and familiar voices.

This comprehensive book explores the many facets of measuring voice quality. Voice quality is a concept that is widely recognized and applied, yet very difficult to define in a way that is universally satisfactory. A number of experts consider such topics as perceptual assessment, instrumental (objective) assessment, and various voice states and disorders. Contributors with a wide scope of experience present perspectives and ideas on how voice quality can be assessed with improved validity and reliability.

The characteristic voice quality of a speaker conveys to listeners a wealth of information about his physical, psychological and social attributes. For this reason, voice quality is of interest to a wide range of disciplines, including linguistics, phonetics and speech science, speech pathology, sociology, psychology, medicine, and communication engineering. Literature on voice quality is, consequently, scattered through a correspondingly wide range of publications. While this bibliography is unlikely to be exhaustive, it aims to be comprehensive. Exceptions to this are purely medical literature and literature on speech pathology; also, although a number of different languages are represented, works in English received the principal coverage.

Foundations of Voice and Speech Quality Perception starts out with the fundamental question of: "How do listeners perceive voice and speech quality and how can these processes be modeled?" Any quantitative answers require measurements. This is natural for physical quantities but harder to imagine for perceptual measurands. This book approaches the problem by actually identifying major perceptual dimensions of voice and speech quality perception, defining units wherever possible and offering paradigms to position these dimensions into a structural skeleton of perceptual speech and voice quality. The emphasis is placed on voice and speech quality assessment of systems in artificial scenarios. Many scientific fields are involved. This book bridges the gap between two quite diverse fields, engineering and humanities, and establishes the new research area of Voice and Speech Quality Perception.

The characteristic voice quality of a speaker conveys to listeners a wealth of information about his physical, psychological and social attributes. For this reason, voice quality is of interest to a wide range of disciplines, including linguistics, phonetics and speech science, speech pathology, sociology, psychology, medicine, and communication engineering. Literature on voice quality is, consequently, scattered through a correspondingly wide range of publications. While this bibliography is unlikely to be exhaustive, it aims to be comprehensive. Exceptions to this are purely medical literature and literature on speech pathology; also, although a number of different languages are represented, works in English received the principal coverage.

Foundations of Voice and Speech Quality Perception starts out with the fundamental question of: "How do listeners perceive voice and speech quality and how can these processes be modeled?" Any quantitative answers require measurements. This is natural for physical quantities but harder to imagine for perceptual measurands. This book approaches the problem by actually identifying major perceptual dimensions of voice and speech quality perception, defining units wherever possible and offering paradigms to position these dimensions into a structural skeleton of perceptual speech and voice quality. The emphasis is placed on voice and speech quality assessment of systems in artificial scenarios. Many scientific fields are involved. This book bridges the gap between two quite diverse fields, engineering and humanities, and establishes the new research area of Voice and Speech Quality Perception.

This study proposes a new spectral representation called the Zeros of Z-Transform (ZZT), which is an all-zero representation of the z-transform of the signal. In addition, new chirp group delay processing techniques are developed for analysis of resonances of a signal. The combination of the ZZT representation with the chirp group delay processing algorithms provides a useful domain to study resonance characteristics of source and filter components of speech. Using the two representations, effective algorithms are developed for: source-tract decomposition of speech, glottal flow parameter estimation, formant tracking and feature extraction for speech recognition. The ZZT representation is mainly important for theoretical studies. Studying the ZZT of a signal is essential to be able to develop effective chirp group delay processing methods. Therefore, first the ZZT representation of the source-filter model of speech is studied for providing a theoretical background. We confirm through ZZT representation that anti-causality of the glottal flow signal introduces mixed-phase characteristics in speech signals. The ZZT of windowed speech signals is also studied since windowing cannot be avoided in practical signal processing algorithms and the effect of windowing on ZZT representation is drastic. We show that separate patterns exist in ZZT representations of windowed speech signals for the glottal flow and the vocal tract contributions. A decomposition method for source-tract separation is developed based on these patterns in ZZT. 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). In this thesis, we propose methods to avoid such problems by modifying the ZZT of a signal and further computing the chirp group delay spectrum. New algorithms based on processing of the chirp group delay spectrum are developed for formant tracking and feature estimation for speech recognition. The proposed algorithms are compared to state-of-the-art techniques. Equivalent or higher efficiency is obtained for all proposed algorithms. The theoretical parts of the thesis further discuss a mixed-phase model for speech and phase processing problems in detail. Index Terms—spectral representation, source-filter separation, glottal flow estimation, formant tracking, zeros of z-transform, group delay processing, phase processing.

This book constitutes the thoroughly refereed post-proceedings of the COST Action 2102 International Workshop on Verbal and Nonverbal Communication Behaviours held in Vietri sul Mare, Italy, in March 2007. The twenty six revised full papers presented together with one introductory paper comprise carefully reviewed and selected participants’ contributions and invited lectures given at the workshop. The papers are organized in topical sections.