Overall evaluation - dimensions of sound quality

A challenging issue in sound-quality research is how to find new, as yet unknown perceptual attributes that contribute to the overall evaluation. To that end, rather than asking listeners to elaborate their verbal repertoire, it might be worthwhile to just require very simple comparative judgments from them, while deriving the underlying dimensional structure from subsequent modeling of the observers' behavior. This approach was taken by presenting a fairly large sample of 79 listeners with all possible pairs of 12 environmental sounds selected for their heterogeneity in psychoacoustical attributes. Judgments of all pairs with respect to overall unpleasantness were analyzed with regard to compliance with the Bradley-Terry-Luce, and the less restrictive preference-tree model. The latter model provided a valid representation of the paired-comparison judgments, and permitted construction of a ratio scale of unpleasantness. Furthermore, it revealed that this attribute may not be considered to be one-dimensional. Instead, three sub-groups of sounds were identified, which could be defined by their (non-acoustical) intrusiveness, and loudness. Within the sub-groups of soft and loud sounds, a combination of two instrumental sound measures, namely psycho-acoustical sharpness and roughness, the latter differing in magnitude for the two groups, explained the unpleasantness judgments very well. (Center contract, with participation of Christian Schmid)