ITU-T Contribution COM12-74-E, Review of Validation Tests for Objective Speech Quality Measures, March 1996

An improvement of the P.861 Perceptual Speech Quality Measure PSQM is given. One of the main problems of the PSQM method is that for loud distortions and time clipping the cognitive processing as used in PSQM does not model the behaviour as found with subjects. This is solved by a simple algorithm which was optimised on one database and validated on another one. The correlation for the second database, on which the method was not trained, increased from 0.85 to 0.97. The improved method, called PSQM+, allows the prediction of subjective speech quality in a wider range of applications when compared to the PSQM method.