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.

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.

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

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.

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.

This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users’ perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences.