A measure for predicting audibility discrimination tresholds

Both in speech synthesis and sound coding it often is beneficial to have a measure that predicts whether, and to what extent, two sounds are different. This paper addresses the problem of estimating the perceptual effects of small modifications to the spectral envelope of a harmonic sound. A recently proposed auditory model is investigated that transforms the physical spectrum into a pattern of specific loudness, as a function of critical band-rate. A distance measure based on the concept of partial loudness is presented, which treats detectability in terms of a partial loudness threshold. The implementation of the model is described, as well as its adaptation to the problem of estimating discrimination thresholds related to modifications of the spectral envelope of synthetic vowels. Data obtained from subjective listening tests using a representative set of stimuli in a 3IFC adaptive procedure show that the model makes reasonably good predictions of the discrimination threshold. Systematic deviations from the predicted thresholds can be related to individual differences in auditory filter selectivity.