Portal de Periódicos da CAPES

Psychoacoustically motivated objective speech quality evaluation procedures, PSQM, and improvements

1999; Acoustical Society of America; Volume: 105; Issue: 2_Supplement Linguagem: Inglês

10.1121/1.425330

1520-9024

John G. Bereends, A.P. Hekstra,

Advanced Adaptive Filtering Techniques

PSQM (Perceptual Speech Quality Measure), measuring speech quality objectively, has been standardized by ITU-T as recommendation P.861. PSQM characterizes the perception of the (degraded) output speech signal of the system in comparison to the (ideal) input speech. A perceptual model is used that maps input and output signals onto psychophysical representations using psychophysical equivalents of frequency (Bark) and intensity (compressed Sone). The quality of the device under test is determined with a simple cognitive mapping from the differences in the psychophysical representation to the perceived speech quality in terms of Mean Opinion Scores (MOS). Within an ITU benchmark testing a limited set of unknown codec distortions the PSQM showed high correlations (around 0.97) between subjectively perceived and objectively measured speech quality. When applying PSQM to a wide variety of real world distortions two major limitations show up: First, dynamic time warping effects, as they will be found, e.g., in Internet telephony, cause a degradation in correlation. Second, the perceptual model that is used within the PSQM method is too simple to account for a wide variety of distortions. This presentation discusses extensions to the PSQM method that allows application to real world distortions.