An identification method for objective quality measurements on speech waveform coders

Objective quality measures provide an economic and practic alternative to the tedious and expensive subjective tests. Furthermore some recently proposed measures predict quality values which correlate quite well with the subjective ones. In this paper the architecture of a measuring equipment to conduct objective quality measures on speech waveform coders is presented and discussed. Only the input and output signals from the coder are needed and an identification algorithm is used to separate the distortion effects introduced by the coder from other nondistorting effects as gains, time shifts, low-pass filtering and so on. The performance of the method is investigated under different conditions and the correlation with subjectively determined results is also reported for a number of ADPCM coders with largely varying parameters.