VoIP quality measurement: subjective VoIP quality estimation model for G.711 and G.729 based on native Thai users

Abstract

This paper presents a mathematical model that has been created from the subjective MOS, instead of modifying or improving the existing objective measurement methods (e.g., E-model) for VoIP quality measurement. The proposed model of VoIP quality measurement method is based on native Thai users who communicate to each other using Thai language, which is a tonal language, unlike English and most western languages. The data have been gathered using conversation-opinion tests with 400 and 354 native Thai subjects for two popular codecs, G.711 and G.729, respectively, referring to effects from two major network factors, packet loss and packet delay. This model is called the Thai subjective VoIP quality evaluation model (ThaiVQE). It has been evaluated using two test sets of subjective MOS, from 50 native Thai subjects for G.711 and 64 native Thai subjects for G.729, then the results have been compared with the E-model results. Based on native Thai users, the evaluation result surprisingly shows that ThaiVQE can contribute better accuracy and reliability than the standard E-model with error reduction of over 13 % for G.711 and 28 % for G.729. Therefore, this is an example study for other countries that have their own languages and cultures to create their subjective MOS model.