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.
Author(s): Alexander Raake
Edition: 1
Year: 2006
Language: English
Pages: 336
Speech Quality of VoIP......Page 4
Contents......Page 10
Preface......Page 14
List of Abbreviations......Page 16
Introduction......Page 24
1.1 Speech......Page 30
1.1.1 Speech Acoustics......Page 32
1.1.2 Speech Perception......Page 33
1.2 Speech Quality......Page 42
1.2.1 Definition of Quality......Page 44
1.2.2 Speech Quality Assessment......Page 45
1.2.3 Quality Elements......Page 47
1.2.4 Speech Quality and Quality of Service......Page 48
2 Speech Quality Measurement Methods......Page 52
2.1 Auditory Methods......Page 53
2.1.1 Utilitarian Methods......Page 54
2.1.2 Analytical Methods......Page 63
2.2 Instrumental Methods......Page 68
2.2.1 Signal-based Models......Page 69
2.2.2 Parameter-based Models......Page 71
2.2.3 Monitoring Models......Page 75
2.3 Speech Quality Measurement Methods: Summary......Page 78
3.1 Speech Transmission Using Internet Protocol......Page 80
3.1.1 VoIP Applications......Page 83
3.1.2 VoIP Quality of Service......Page 84
3.2 Overview of Quality Elements......Page 85
3.3.2 Codecs......Page 87
3.3.4 Delay......Page 90
3.3.5 Packet Loss......Page 92
3.3.6 Bit Errors......Page 107
3.3.7 Talker Echo......Page 108
3.3.9 Echo Cancellers......Page 109
3.3.10 Loudness......Page 111
3.3.11 Noise......Page 112
3.3.13 Linear Distortion and Wideband Transmission......Page 114
3.3.14 User Interfaces......Page 119
3.4 Quality Dimensions......Page 120
3.6 Listening and Conversational Features......Page 127
3.7 Desired Nature......Page 128
3.7.2 Cost......Page 130
3.8 Open Questions......Page 131
3.9 From Elements to Features: Modeling VoIP Speech Quality......Page 132
3.9.1 Signal-based Measures and VoIP......Page 133
3.9.2 Parametric Models and VoIP......Page 134
3.10 Quality Elements and Quality Features of VoIP: Summary......Page 137
4 Time-Varying Distortion: Quality Features and Modeling......Page 140
4.1.1 Random Packet Loss......Page 142
4.1.2 Dependent Packet Loss......Page 152
4.2 Macroscopic Loss Behavior......Page 158
4.2.1 Macroscopic Loss with Segments of Random Loss......Page 159
4.2.2 Macroscopic Loss with Segments of Dependent Loss......Page 164
4.3 Interactivity......Page 176
4.4 Packet Loss and Combined Impairments......Page 180
4.4.1 Additivity and Multidimensional Feature Space......Page 181
4.4.2 Microscopic Loss Behavior: Random Packet Loss......Page 183
4.4.3 Macroscopic Loss Behavior: 3-State Markov Loss......Page 191
4.4.4 Model: Packet Loss and Combined Impairments......Page 197
4.5 Time-Varying Distortion: Summary......Page 201
5 Wideband Speech, Linear and Non Linear Distortion: Quality Features and Modeling......Page 204
5.1 Wideband Speech: Improvement Over Narrowband......Page 205
5.2 Bandpass-Filtered Speech......Page 210
5.2.1 Listening Test......Page 211
5.2.2 Parametric Impairment Model......Page 213
5.3 Wideband Codecs......Page 218
5.4 Desired Nature......Page 219
5.4.1 User Interfaces......Page 221
5.4.2 Content......Page 226
5.4.3 Summary......Page 232
6.1 E-model: Packet Loss......Page 234
6.2 E-model: Additivity......Page 235
6.3 E-model: Wideband, Linear and Non-Linear Distortion......Page 237
7 Summary and Conclusions......Page 240
8 Outlook......Page 244
A.1 4-state Markov Chain: Sojourn in Bad and Good State......Page 246
A.2.1 Forward Error Correction......Page 248
A.2.2 Jitter and Jitter Buffer......Page 249
A.3 Impairment under GSM Bit Errors......Page 252
B Simulation of Quality Elements......Page 254
B.1 PSTN/ISDN......Page 255
B.2 Mobile Networks......Page 257
B.3.1 Analog to ISDN Conversion......Page 258
B.3.2 VoIP Gateways......Page 259
B.3.3 IP Network Simulation......Page 260
B.3.4 Instrumental Verification......Page 262
B.5 User Interfaces......Page 263
B.5.3 Wideband Handset and Hi-fi Phone......Page 264
B.5.4 Bandpass Filters......Page 266
B.5.5 Hands-free Terminals (HFTs)......Page 267
B.7 Simulation of Quality Elements: Summary......Page 270
C.1.1 Narrowband......Page 274
C.1.2 Wideband......Page 275
C.2.1 Headsets......Page 276
C.2.2 Wideband Handsets......Page 277
D.1 Equivalent-Q Method......Page 280
D.3 Linear Transformation......Page 281
D.4 Note on MOS-terminology......Page 282
E E-model Algorithm......Page 284
F Interactive Short Conversation Test Scenarios (iSCTs)......Page 290
F.1 Example......Page 291
G.1 Global System for Mobile (GSM): Short Conversation and Listening Only Test......Page 294
G.2 2-state Markov Loss: Listening Only Test......Page 296
G.3.1 Test Setup......Page 297
G.3.2 Test Procedure......Page 298
G.3.4 Details on Selected Results......Page 299
G.4.1 Test Setup......Page 300
G.4.2 Test Procedure and Test Subjects......Page 301
G.4.3 Details on Selected Results......Page 302
G.5 Speech Sound Quality and Content......Page 303
H.1.1 Macroscopic Loss Behavior......Page 306
I Glossary......Page 310
Bibliography......Page 314
Index......Page 332
