New reference condition for very low bit rate voice coder evaluation

The standard reference signal for speech quality studies is speech correlated noise, which is especially useful for characterizing the reduction in speech quality due to digital processing in transmission facilities. The results of two studies designed to characterize the suitability of speech correlated noise and a new type of reference condition, called temporally correlated noise, for use in evaluating the speech quality of very low bit rate voice (VLBRV) algorithms are reported. The results suggest that temporally correlated noise is a more appropriate reference condition for the speech quality evaluation of VLBRV coders because it sounds similar to the impairments introduced by these coders