Assessment And Prediction Of Speech Quality In Telecommunications

The quality of a telecommunication voice service is largely inftuenced by the quality of the transmission system. Nevertheless, the analysis, synthesis and prediction of quality should take into account its multidimensional aspects. Quality can be regarded as a point where the perceived characteristics and the desired or expected ones meet. A schematic is presented which classifies different entities which contribute to the quality of a service, taking into account conversational, user as weIl as service related contributions. Starting from this concept, perceptively relevant constituents of speech communication quality are identified. The perceptive factors result from ele ments of the transmission configuration. A simulation model is developed and implemented which allows the most relevant parameters of traditional trans mission configurations to be manipulated, in real time and for the conversation situation. Inputs into the simulation are instrumentally measurable quality elements commonly used in transmission planning of telephone networks. A reduced set of these quality elements forms a basis for models which aim at predicting mouth-to-ear quality as it would be perceived by a user of the sys tem. These models are an important tool for the planner of telecommunication networks, as they allow the expected quality to be estimated in advance, even before the network has been set up. Two well-known models (the SUBMOD and the E-model) are analyzed in more detail, with an emphasis on the psy choacoustic and psychophysical backgrounds.

This work deals with the instrumental measurement methods for the perceived quality of transmitted speech. These measures simulate the speech perception process employed by human subjects during auditory experiments. The measure standardized by the International Telecommunication Union (ITU), called “Wideband-Perceptual Speech Quality Evaluation (WB-PESQ)”, is not able to quantify all these perceived characteristics on a unidimensional quality scale, the Mean Opinion Score (MOS) scale. Recent experimental studies showed that subjects make use of several perceptual dimensions to judge about the quality of speech signals. In order to represent the signal at a higher stage of perception, a new model, called “Diagnostic Instrumental Assessment of Listening quality (DIAL)”, has been developed. It includes a perceptual and a cognitive model which simulate the whole quality judgment process. Except for strong discontinuities, DIAL predicts very well speech quality of different speech processing and transmission systems, and it outperforms the WB-PESQ.

Quality of Telephone-Based Spoken Dialogue Systems is a systematic overview of assessment, evaluation, and prediction methods for the quality of services such as travel and touristic information, phone-directory and messaging, or telephone-banking services. A new taxonomy of quality-of-service is presented which serves as a tool for classifying assessment and evaluation methods, for planning and interpreting evaluation experiments, and for estimating quality. A broad overview of parameters and evaluation methods is given, both on a system-component level and for a fully integrated system. Three experimental investigations illustrate the relationships between system characteristics and perceived quality. The resulting information is needed in all phases of system specification, design, implementation, and operation. Although Quality of Telephone-Based Spoken Dialogue Systems is written from the perspective of an engineer in telecommunications, it is an invaluable source of information for professionals in signal processing, communication acoustics, computational linguistics, speech and language sciences, human factor design and ergonomics

Finally a comprehensive overview of speech quality in VoIP from the user's perspective! Speech Quality of VoIP is an essential guide to assessing the speech quality of VoIP networks, whilst addressing the implications for the design of VoIP networks and systems. This book bridges the gap between the technical network-world and the psychoacoustic world of quality perception. Alexander Raake’s unique perspective combines awareness of the technical characteristics of VoIP networks and original research concerning the perception of speech transmitted across them. Starting from the network designer’s point of view, the different characteristics of the network are addressed, and then linked to features perceived by users. This book provides an overview of the available knowledge on the principal, relevant aspects of speech and speech quality perception, of speech quality assessment, and of transmission properties of telephone and VoIP networks, and of the related perceptual features and resulting speech quality. Discussing new research into the specific time-varying degradations VoIP brings along, but also the considerable potential of quality improvement to be achieved with wideband speech transmission, Alexander Raake demonstrates how network and service characteristics impact on the users perception of quality. Speech Quality of VoIP: Offers an insight into speech quality of VoIP from a user's perspective. Presents an overview of different modelling approaches and a parametric network-planning model for quality prediction in VoIP networks. Draws on innovative new research on the quality degradation characteristic of VoIP. Explains in detail how telephone speech quality can be greatly enhanced with VoIP’s wideband speech transmission capability. Assesses the vast collection of references into the technical and scientific literature related to VoIP quality. Illustrates concepts throughout with mathematical models, algorithms and simulations. Speech Quality of VoIP is the definitive guide for researchers, engineers and network planners working in the field of VoIP, Quality of Service, and speech communication processing in telecommunications. Advanced undergraduate and graduate students on telecommunication and networking courses will also find this text an invaluable resource.

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 work presented in this book focuses on modeling audiovisual quality as perceived by the users of IP-based solutions for video communication like videotelephony. It also extends the current framework for the parametric prediction of audiovisual call quality. The book addresses several aspects related to the quality perception of entire video calls, namely, the quality estimation of the single audio and video modalities in an interactive context, the audiovisual quality integration of these modalities and the temporal pooling of short sample-based quality scores to account for the perceptual quality impact of time-varying degradations.

In this book, speech transmission quality is modeled on the basis of perceptual dimensions. The author identifies those dimensions that are relevant for today's public-switched and packet-based telecommunication systems, regarding the complete transmission path from the mouth of the speaker to the ear of the listener. Both narrowband (300-3400 Hz) as well as wideband (50-7000 Hz) speech transmission is taken into account. A new analytical assessment method is presented that allows the dimensions to be rated by non-expert listeners in a direct way. Due to the efficiency of the test method, a relatively large number of stimuli can be assessed in auditory tests. The test method is applied in two auditory experiments. The book gives the evidence that this test method provides meaningful and reliable results. The resulting dimension scores together with respective overall quality ratings form the basis for a new parametric model for the quality estimation of transmitted speech based on the perceptual dimensions. In a two-step model approach, instrumental dimension models estimate dimension impairment factors in a first step. The resulting dimension estimates are combined by a Euclidean integration function in a second step in order to provide an estimate of the total impairment.

Quality of Telephone-Based Spoken Dialogue Systems is a systematic overview of assessment, evaluation, and prediction methods for the quality of services such as travel and touristic information, phone-directory and messaging, or telephone-banking services. A new taxonomy of quality-of-service is presented which serves as a tool for classifying assessment and evaluation methods, for planning and interpreting evaluation experiments, and for estimating quality. A broad overview of parameters and evaluation methods is given, both on a system-component level and for a fully integrated system. Three experimental investigations illustrate the relationships between system characteristics and perceived quality. The resulting information is needed in all phases of system specification, design, implementation, and operation. Although Quality of Telephone-Based Spoken Dialogue Systems is written from the perspective of an engineer in telecommunications, it is an invaluable source of information for professionals in signal processing, communication acoustics, computational linguistics, speech and language sciences, human factor design and ergonomics

This book provides a new multi-method, process-oriented approach towards speech quality assessment, which allows readers to examine the influence of speech transmission quality on a variety of perceptual and cognitive processes in human listeners. Fundamental concepts and methodologies surrounding the topic of process-oriented quality assessment are introduced and discussed. The book further describes a functional process model of human quality perception, which theoretically integrates results obtained in three experimental studies. This book's conceptual ideas, empirical findings, and theoretical interpretations should be of particular interest to researchers working in the fields of Quality and Usability Engineering, Audio Engineering, Psychoacoustics, Audiology, and Psychophysiology. Presents a new process-oriented approach towards speech quality assessment to uncover influences of speech transmission quality on human information processing; Proposes a multi-method assessment approach including subjective, behavioral, and neurophysiological levels of analysis; Reports findings from three experimental studies, that demonstrate interactions between perceived speech quality, contextual, and content-related influencing factors.

Written by the world's top experts in the field, this multidisciplinary book explores all phases of speech technology. Topics covered include: Conversion of computerized (keyboarded) text into synthesized speech, aimed at developing "talking computers" Development of automatic speech recognition, allowing electronic devices to process verbal commands Speech training and the use of synthesized speech for the hearing- and speech-impaired In-depth discussions of specific speech technologies are included, as well as a treatment of the issues and challenges of human-computer interfaces. Oriented toward state-of-the-art applications, the book emphasizes the practical utilization of emerging technologies and includes numerous case studies.