Quality Assessment in Telecommunications
If the perceptive effects of the factors discussed so far are to be qualified or quantified, auditory assessment methods are needed. Besides the test object, the choice of an adequate test method is the principle influencing factor on what information on quality can be obtained as the result of an assessment. It is therefore necessary to discuss in more detail the principle quality assessment methods and methodologies used in telephony, and to point out which consequences result for the outcome in terms of quality dimensions. In Sections 1 to 8 various assessment methods are analyzed regarding the perceptive dimensions they refer to. The analysis includes the influences resulting from the choice of test subjects, the test procedure, the scaling method, the test modality, etc. It turns out that there is no optimal test method for all or for general purposes, but that an appropriate method has to be chosen according to the assessment task. With respect to the quality dimension which is assessed, the test methods can be classified in the QoS schematic defined in Chapter 2, see Section 10. In order to get valid estimates of integral speech communication quality in telephone situations, an economical conversation test methodology is developed, see Section 9. This methodology is used in the following in order to investigate the relationship between factors governing the quality of a service (Chapter 6) and the quality of prediction models (Chapter 7).
KeywordsQuality Assessment Speech Signal Test Subject Category Scale User Survey
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