Feature Selection in Auditory Perception
CATHOLIC UNIV OF AMERICA WASHINGTON DC HUMAN PERFORMANCE LAB
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Feature extraction plays a fundamental role in most theories of pattern recognition, but despite its importance, the extraction process is not well defined. Two contrasting views of feature extraction can be identified, one which emphasizes invariant feature detection and one which emphasizes flexible feature selection. The invariant detector approach assumes that the auditory system is equipped with finely tuned feature detectors that respond to specific stimulus properties. In this view, stimuli are described in terms of property lists of specific features. In contrast, the more flexible, process-oriented approach assumes that the auditory system is equipped with a set of rules and criteria for feature selection. In this view, the important perceptual features reflect the underlying structure of the stimuli. Research on timbre and pitch perception has supported a flexible, process-oriented approach. The flexibility of this approach offers particular advantages in that it can explain the effects of stimulus and task context on performance. Both types of context influence the perception of complex sounds. Stimulus context affects the structure of the stimulus space and consequently the features that would be extracted by a structure preserving transformation. Task context affects the relative importance of features in making similarity judgements and classification decisions. The two approaches to feature extraction have important implications for the development of auditory pattern recognition theory.