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.

This volume presents a parametric, packet-based, comprehensive model to measure and predict the audiovisual quality of Internet Protocol Television services as it is likely to be perceived by the user. The comprehensive model is divided into three sub-models referred to as the audio model, the video model, and the audiovisual model. The audio and video models take as input a parametric description of the audiovisual processing path, and deliver distinct estimates for both the audio and video quality. These distinct estimates are eventually used as input data for the audiovisual model. This model provides an overall estimate of the perceived audiovisual quality in total. The parametric description can be used as diagnostic information. The quality estimates and diagnostic information can be practically applied to enhance network deployment and operations. Two applications come to mind in particular: Network planning and network service quality monitoring. The audio model can be used indifferently for both applications. However, two variants of the video model have been developed in order to address particular needs of the applications mentioned above. The comprehensive model covers effects due to resolution, coding, and IP-packet loss in case of RTP-type transport. The model applied to quality monitoring is standardized under the ITU-T Recommendations P.1201 and P.1201.2.

This book provides an in-depth investigation of the quality relevant perceptual video space in the domain of videotelephony. The author presents an extensive investigation and quality modeling of the underlying video quality dimensions and the overall quality. The author examines the underlying quality dimensions and describes a method for subjective evaluation as well as the instrumental estimation of video quality in videotelephony. The book presents a new subjective test method in the field of video quality assessment. Further, it explains the experimental examination of the underlying video quality dimensions and the subjective-based, as well as instrumental-based quality estimation. Provides an investigation of the underlying quality dimensions of video in videotelephony; Presents insights into a new subjective test method, standardized as ITU-T Rec. P.918; Includes insights into the subjective and instrumental video quality estimation.

This book presents how to apply recent machine learning (deep learning) methods for the task of speech quality prediction. The author shows how recent advancements in machine learning can be leveraged for the task of speech quality prediction and provides an in-depth analysis of the suitability of different deep learning architectures for this task. The author then shows how the resulting model outperforms traditional speech quality models and provides additional information about the cause of a quality impairment through the prediction of the speech quality dimensions of noisiness, coloration, discontinuity, and loudness.

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 pioneering book develops definitions and concepts related to Quality of Experience in the context of multimedia- and telecommunications-related applications, systems and services and applies these to various fields of communication and media technologies. The editors bring together numerous key-protagonists of the new discipline “Quality of Experience” and combine the state-of-the-art knowledge in one single volume.

This book shows how networking research and quality engineering can be combined to successfully manage the transmission quality when speech and video telephony is delivered in heterogeneous wireless networks. Nomadic use of services requires intelligent management of ongoing transmission, and to make the best of available resources many fundamental trade-offs must be considered. Network coverage versus throughput and reliability of a connection is one key aspect, efficiency versus robustness of signal compression is another. However, to successfully manage services, user-perceived Quality of Experience (QoE) in heterogeneous networks must be known, and the perception of quality changes must be understood. These issues are addressed in this book, in particular focusing on the perception of quality changes due to switching between diverse networks, speech and video codecs, and encoding bit rates during active calls.