First ISCA ITRW on Auditory Quality of Systems
April 23-25, 2003
One of the major goals of current sound-quality research has been to develop automated, objective metrics of perceptual attributes. These metrics have to be validated against subjective measures of the attributes which they claim to capture. To that end, typically, verbal reports are collected on complex psychophysical attributes from observers directly. That procedure, however, involves the risk of accumulating data of unknown validity, dimensionality, and unit. Rather than getting at the dimensions of interest directly, it is therefore advocated to ask but very simple judgments of preference from observers. Such data may then be used to model the listener’s decision strategies when comparing auditory events. Once a valid decision model has been established, psychophysical scale values may be derived. The focus of the presentation will be on two approaches, the Bradley-Terry-Luce model, and the representation of paired comparisons by ’preference trees,’ which will be illustrated with examples from sound-quality research. It is shown that these ’indirect approaches offer (a) the advantage of an explicitly stated theory about the observer’s decision strategy, with (b) built-in checks of the consistency of judgments, and (c) statistical tests to validate if the attempt at scale construction succeeded or failed. In that way, indirect methods are able to (d) reveal the dimensional structure behind psychoacoustical judgments, and (e) provide the possibility to discover ’new,’ as yet undetected auditory attributes.
Bibliographic reference. Ellermeier, Wolfgang / Zimmer, Karin (2003): "Using psychological choice models to investigate overall sound quality", In AQS-2003, 71-78.