A model for evaluating talker echo and sidetone in a telephone transmission network

An objective evaluation model called OPINE (overall performance index model for network evaluation) which is being studied for telephone transmission quality is described. The model estimates an MOS (mean opinion score) by summing psychological values on independent psychological factors, given the physical values of fundamental listening factors such as loss and noise. For the model to incorporate new talking factors such as talker echo and sidestone, evaluation characteristics are studied when both listening and talking factors are present in a telephone transmission system. The interaction of the listening and talking factors is discussed, and it is shown experimentally that these factors are independent of fundamental listening factors. From these results, an extended OPINE is proposed by establishing new psychological factors: talker echo and sidestone. The estimated MOS for composite conditions of listening and talking factors agrees well within the confidence interval of subjective MOS deviation