Title

A TEST OF AN AUDITORY MOTION HYPOTHESIS FOR CONTINUOUS AND DISCRETE SOUNDS MOVING IN PITCH SPACE

Date of Award

2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Psychology/Experimental

First Advisor

Devin McAuley, PhD

Second Advisor

Rodney Gabel, PhD (Committee Member)

Third Advisor

Jennifer Gillespie, PhD (Committee Member)

Fourth Advisor

Dale Klopfer, PhD (Committee Member)

Abstract

Ten experiments tested an auditory motion hypothesis, which proposes that regular pitch-time trajectories facilitate perception of and attention to auditory stimuli; on this view, listeners are assumed to use velocity information (pitch change per unit time) to generate expectations about the future time course of continuous and discrete sounds moving in pitch space. Toward this end, two sets of experiments were conducted. In six experiments reported in Part I of this dissertation, listeners judged the duration or pitch change of a continuous or discrete comparison stimulus relative to a standard, where the comparison’s velocity varied on each trial relative to the fixed standard velocity. Results indicate that expectations generated based on velocity information led to distortions in perceived duration and pitch change of continuous stimuli that were consistent with the auditory motion hypothesis; specifically, when comparison velocity was relatively fast, duration was overestimated and pitch change was underestimated. Moreover, when comparison velocity was relatively slow, duration was underestimated and pitch change was overestimated. On the other hand, no perceptual distortions were observed for discrete stimuli, consistent with the idea that velocity information is less clearly conveyed, or easier to ignore, for discrete auditory stimuli.

Four experiments reported in Part II tested the hypothesis that listeners tune attention to expected pitch-time locations of future events based on velocity information conveyed by continuous and discrete auditory stimuli. Listeners detected pure-tone signals in noise that were expected or unexpected based on extrapolation of the trajectory of ascending or descending glides or sequences. Consistent with the auditory motion hypothesis, results indicate that listeners used pitch-time trajectory information in continuous and discrete auditory stimuli to tune attention; that is, listeners were most sensitive to detect expected relative to unexpected signals, and results were similar for continuous and discrete cues. However, consistent with an auditory gravity hypothesis, large asymmetries were observed for ascending versus descending cues, with listeners overshooting the expected pitch location of signals following descending cues. Taken together, the results support the hypothesis that listeners use velocity information to generate expectations about the future time course of sounds moving in pitch space.