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 innovation new research on the quality degradation characteristic of VoIP.
- Explains in detail how telephone speech quality can be 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.
List of Abbreviations.
1 Speech Quality in Telephony.
1.2 Speech Quality.
2 Speech Quality Measurement Methods.
2.1 Auditory Methods.
2.2 Instrumental Methods.
2.3 Speech Quality Measurement Methods: Summary.
3 Quality Elements and Quality Features of VoIP.
3.1 Speech Transmission Using Internet Protocol.
3.2 Overview of Quality Elements.
3.3 Quality Elements and Related Features.
3.4 Quality Dimensions.
3.5 Combined Elements and Combined Features.
3.6 Listening and Conversational Features.
3.7 Desired Nature.
3.8 Open Questions.
3.9 From Elements to Features: Modeling VoIP Speech Quality.
3.10 Quality Elements and Quality Features of VoIP: Summary.
4 Time–Varying Distortion: Quality Features and Modeling.
4.1 Microscopic Loss Behavior.
4.2 Macroscopic Loss Behavior.
4.4 Packet Loss and Combined Impairments.
4.5 Time–Varying Distortion: Summary.
5 Wideband Speech, Linear and Non Linear Distortion: Quality Features and Modeling.
5.1 Wideband Speech: Improvement Over Narrowband.
5.2 Bandpass–Filtered Speech.
5.3 Wideband Codecs.
5.4 Desired Nature.
6 From Elements to Features: Extensions of the E–model.
6.1 E–model: Packet Loss.
6.2 E–model: Additivity.
6.3 E–model: Wideband, Linear and Non–Linear Distortion.
7 Summary and Conclusions.
A Aspects of a Parametric Description of Time–Varying Distortion.
B Simulation of Quality Elements.
C Frequency Responses.
D Test Data Normalization and Transformation.
E E–model Algorithm.
F Interactive Short Conversation Test Scenarios (iSCTs).
G Auditory Test Settings and Results.
H Modeling Details.