Development of a MOS estimation model for G.729 using listening-opinion tests with Thai speech referring to packet loss effects

This paper presents a proposed mathematical model of VoIP quality estimation from G.729. This model is based on native Thai users. The subjective Mean Opinion Score (MOS) were obtained from listening-opinion tests with a total of 102 subjects that covered five conditions of packet loss effects (0%, 3%, 5%, 10% and 20%). The model was then created using a simple function in Microsoft Excel, before evaluating with the test set data obtained from four test conditions (0%, 4%, 8% and 12%) with 30 subjects. From the evaluated result, it has been found that the Mean Absolute Percent Error (MAPE) of the model is 16.29%. That means this model is accepted as a good model for MOS estimation from G.729 for Thai users, referring to packet loss effects (0-10% =excellent, whereas about 10-20% = good).