Methods of Improving the Accuracy and Reproducibility of Objective Quality Assessment of VoIP Speech


IEICE TRANSACTIONS on Communications   Vol.E87-B   No.6   pp.1660-1669
Publication Date: 2004/06/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Multimedia Systems
VoIP,  objective quality assessment,  speech quality,  subjective quality,  QoS,  

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VoIP is one of the key technologies for recent telecommunication services. The quality of its services should be discussed in subjective terms. Since subjective quality assessment is time-consuming and expensive, however, objective quality assessment which estimates subjective quality without carrying out subjective quality experiments is desirable. This paper discusses the performance of the objective quality measure that was standardized as ITU-T Recommendation P.862 and clarifies the quality factors that can be evaluated with satisfactory accuracy based on it. We found that P.862 can be applied to the evaluation of coding distortion, tandeming of codecs, transmission bit-errors, packet loss, and silence compression in a codec, at least for clean Japanese speech. In addition, we propose a method of estimating the subjective quality evaluation value from objective measurement results and show the validity of this method. We also evaluate the uniqueness of objective quality assessment based on P.862 from the viewpoints of the effect of measurement noise and the variation of test speech samples, and propose how to improve the reproducibility of objective quality assessment.