Feature Assignment in Perception of Auditory Figure and Ground
Gregg, Melissa Kay
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Many critical skills rely on the ability to successfully sort out the auditory sensory information in an auditory scene. For example, in order to communicate successfully, listeners must be able to segregate incoming speech from other co-occurring sounds, such as a telephone ringing, background music, car horns, and speech coming from a nearby source. The task of segregating an auditoryobject of interest from other co-occurring sounds is one of identifying an organized auditory figure against the unattended auditory ground. In this project, I conducted a series of experiments intended to contribute to a basic understanding of how auditory figure and ground analysis is accomplished. The first part of this project utilized behavioral methods to determine how the relationship between the object in figure and the objects in ground affects the auditory system's assignment of a feature to those objects. One finding thatoccurred across experimental manipulations was that the auditory system is more likely to allocate a feature to an object that needs the feature in order to be a meaningful object. This finding did not occur as often in more complicated perceptual scenarios, presumably because of increased competition for the feature.The second part of this project was designed to address the fate offeatures in auditory ground. Behavioral and physiological methods were used to determine if features are assigned to objects in perceptual ground or to perceptual groups in ground. The results indicated that features are assigned to objects in the background, but not to perceptual groups. The results suggest that the nature of perceptual ground is not a free-floating perceptual limbo. Rather,objects appear to be well constructed in ground.