UC Riverside

ABSTRACT OF THE DISSERTATION

The Influences of Spatial and Motion Properties on Auditory Grouping

by

Ryan Robart

Doctor of Philosophy, Graduate Program in Psychology

University of California, Riverside, December 2010

Dr. Lawrence D. Rosenblum, Chairperson

Despite a plethora of research and theory on spatial hearing and the perceptual organization of sound, the question of the relative importance of spatial and frequency relations in low level auditory grouping remains (Bregman, 1990; Rogers & Bregman, 1993; 1998; Strybel and Neale 1998; Kubovy & VanValkenberg, 2001). Most researchers share the assumption that frequency relations of sounds dominate spatial relations in the perceptual organization of sound. In a natural context, sound sources (e.g. automobiles) create sound that has a broad range of frequency content, but a limited -and often predictable-- range of motion. It could be that in a natural context, the coherent movement of sound components may be more important in forming auditory groups than frequency similarity among those components. The research conducted in this project tested a new theory that assumes spatial relations can dominate frequency relations in grouping (dynamic spatial assessment after initial localization [DSAIL]). Based on the free-field methods used by Rogers & Bregman (1993; 1998), listeners' in these experiments reported the extent of their perceptual grouping of simple tone sequences under various spatial manipulations. In many cases, the results showed that grouping varied systematically with coherent motion-type [opposite trajectory vs shared trajectory] and angular separation [far (>90°) vs near (<90°) among the tones. The implications of these results are discussed.