Objective modeling of speech quality with a psychoacoustically validated auditory model

A new objective measure for the transmission quality of low-bit-rate speech coding algorithms is described and tested. A quantitative psychoacoustical signal processing model is employed to measure the perceptually relevant d eviations between the transmitted, degraded signal and the corresponding re ference signal objectively. The processing is applied to transform the code d (distorted) signal and the corresponding original speech signal to an int ernal representation which is thought of as the information that is accessi ble to higher neural stages of perception. From a comparison of these inter nal representations a quality measure can be derived, which shows a high co rrelation with the subjective mean opinion score data of various test datab ases if a frequency-dependent weighting is applied that exhibits increasing weights for increasing center frequencies of the filter channels of the in ternal representation. The inherent parameters of the auditory processing m odel optimized from psychoacoustical data independent from the present stud y yielded also the best performance in predicting the subjective speech qua lity data compared to alterations of the auditory model. The performance of the new measure was investigated by comparing it with alternative models w ith regard to dynamic compression and with the PSQM/P.861 measure. The perf ormance of the proposed model was on average comparable to that of the PSQM model.