Investigation the Ability of Objective Measures of the Perceptual Speech Quality in Mobile Networks
There is continued the work of iQoS module creation. Possibilities to create special module which should measure de facto perceived speech quality (iQoS module) are investigated. The paper thoroughly reviews scientific publications about QoS measurement. After analysis of published works it is shown that currently prevailing methods of speech quality evaluation are not directly applicable for the evaluation of conversational speech quality because they make an assumption that distortions are stationary. Research of single word distortions shows that in most cases even one lost frame worsens voice quality so that user satisfaction category changes to lower level. Deterministic relation between lost frame position in a word and quality degradation was not observed so it is possible to postulate that relation is stochastic in nature. Obtained empirical distributions of voice quality degradation confirm this assumption. The purpose of research continuation is to determine correlation between amount of erased frames and perceived quality level. The paper has formed a list of tasks which is necessary to solve in order to implement iQoS concept. Ill 5, bibl. 10 (in English; summaries in Lithuanian, English, Russian).
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