Assessment and Prediction of Speech Quality in Telecommunications

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Springer Science & Business Media, Aug 31, 2000 - Science - 244 pages
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The quality of telecommunication voice services has become an important issue due to the evolving and liberalized market. With the advent of new technologies, however, a diversification takes place which makes it necessary to carefully plan and observe network quality. Speech communication quality - as it is perceived by the user or customer of a service - carries a multidimensional nature, a fact which must be reflected in its assessment and prediction with quality models. In this book a new schematic is developed which classifies different entities contributing to the quality of a service. It takes into account conversational user as well as service-related contributions. Starting from this concept, perceptively relevant constituents of speech communication quality are identified. A simulation model is developed and implemented, based on physical elements of the transmission configuration. It allows the perceptively most relevant parameters to be simulated, in real time and for the conversation situation. The book gives a valuable overview on assessment needed for reliably measuring the different quality dimensions. For the planning of telephone networks, quality models are presented which aim at predicting mouth-to-ear quality as it would be perceived by a user of the system. 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 psychoacoustic and psychophysical backgrounds. It turns out that model predictions are satisfactory for many types of degradations, but they can still be improved especially for new types of impairments. Proposals are made for quality model enhancement and combined approaches. Due to its `handbook' character, this book is an invaluable source of background information for anyone working in the field of speech quality assessment as well as telephone network planning and operation.
 

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Contents

INTRODUCTION
1
CONSIDERATIONS ON QUALITY
7
2 QUALITY IN THE CONTEXT OF TELECOMMUNICATIONS
11
FACTORS INFLUENCING THE QUALITY OF SERVICE
17
1 PERCEPTIVE FACTORS
18
11 LOUDNESS
19
12 ARTICULATION
26
13 EFFECTS OF BANDWIDTH RESTRICTION AND FREQUENCY DISTORTION
27
22 DESCRIPTION OF THE EMODEL
99
3 INSTRUMENTAL MODELS FOR SINGLE TRANSMISSION ASPECTS
102
4 CALL SETUP AND CALL COMPLETION MODELS
104
5 CUSTOMER BEHAVIOR MODELS
108
6 APPLICATION AND CLASSIFICATION OF PREDICTION MODELS
109
7 SUMMARY
111
RELATIONS BETWEEN FACTORS GOVERNING THE QUALITY OF SERVICE
115
1 RELATIVE QUALITY VERSUS ABSOLUTE QUALITY
116

14 PERCEPTION OF SIDETONE
28
15 PERCEPTION OF ECHO
30
16 PERCEPTION OF CIRCUIT NOISE
32
17 PERCEPTION OF AMBIENT NOISE
33
18 EFFECTS OF TRANSMISSION DELAY
34
2 CONFIGURATION OF A TELEPHONE CONNECTION
35
3 SIMULATION OF A TELEPHONE CONNECTION FOR QUALITY ASSESSMENT PURPOSES
38
4 CLASSIFICATION OF TRANSMISSION AND SERVICE PARAMETERS
43
5 SUMMARY
45
QUALITY ASSESSMENT IN TELECOMMUNICATIONS
47
1 CHOICE OF TEST SUBJECTS
50
2 ARTICULATION AND INTELLIGIBILITY TESTS
51
31 LISTENINGONLY TESTS USING ABSOLUTE CATEGORY RATING
52
32 LISTENINGONLY TESTS USING PAIRED COMPARISON TECHNIQUES
54
33 MULTIDIMENSIONAL ANALYSIS
56
34 TALKING AND LISTENING TESTS
58
35 CONVERSATION TESTS
59
4 PERFORMANCE TESTS
60
5 USER SURVEYS
61
6 USABILITY EVALUATION
63
7 ASSESSMENT OF COSTRELATED FACTORS
65
8 SCALING
66
81 RATIO SCALING
68
83 CATEGORYRATIO SCALING
72
9 DEVELOPMENT OF CONVERSATION TEST SCENARIOS
75
92 EXPERIENCES WITH TWO DIFFERENT TYPES OF SCENARIO
78
93 SCENARIOS FOR SPECIAL APPLICATIONS
81
10 CLASSIFICATION OF ASSESSMENT METHODS
85
MODELS FOR PREDICTING SPEECH COMMUNICATION QUALITY AND SERVICERELATED MODELS
89
1 MOUTHTOEAR MODELS USING PARAMETERS IN THE FREQUENCY DOMAIN
91
2 MOUTHTOEAR MODELS USING SCALAR PARAMETERS
94
21 THE ADDITIVITY PROPERTY OF THE EMODEL
96
2 REFERENCES AND NORMALIZATION
121
3 ASSESSMENT IN LISTENINGONLY AND CONVERSATION TESTS
129
4 EXPECTATION
133
5 INFLUENCE OF THE COST FACTOR
141
6 MULTIDIMENSIONAL ASSESSMENT OF VOICE TRANSMISSION QUALITY
145
PSYCHOLOGICAL QUALITY SCALE
147
8 SUMMARY
155
QUALITY OF PREDICTION MODELS
159
1 PREDICTION FOR SINGLE PERCEPTIVE TYPES OF IMPAIRMENT
160
2 PREDICTION FOR COMBINATIONS OF DIFFERENT TYPES OF IMPAIRMENT
167
3 IMPAIRMENT FACTOR PRINCIPLE FOR LOWBITRATE CODECS
172
4 PREDICTION OF FREQUENCY CHARACTERISTICS
176
5 MEASUREMENT OF THE INPUT PARAMETERS
184
6 ACCURACY OF QUALITY PREDICTIONS LIMITATIONS
185
7 SUMMARY
186
FINAL DISCUSSION AND CONCLUSIONS
189
Glossary
197
Perceptive Characteristics Resulting from New Technologies
199
2 CLASSIFICATION FOR MODELING PURPOSES
201
Discussion of Articulation and Intelligibility Test Methodologies
205
GraecoLatinSquare Test Design
207
SCT Scenarios
209
2 EXPLANATIONS OF THE SCT DIALOG STRUCTURE GIVEN TO THE TEST SUBJECTS
213
Closing Questionnaire Given after Laboratory Tests
215
EModel Algorithm
217
Test Conditions and Results
221
2 RELATION BETWEEN EMODEL PREDICTIONS AND TEST RESULTS
222
3 COMPARISON OF SUBMOD MODEL PREDICTIONS AND TEST RESULTS
225
Bibliography
227
Index
241
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