Lateralization of Sinusoidally - Amplitude-Modulated Tones: Effects of Spectral Locus and Temporal Variation

The purpose of this study was to evaluate, as a function of spectral locus and temporal variation, the lateralization of sinusoidally-amplitude-modulated tones. An acoustic pointing task was employed in which listeners varied the interaural intensitive disparity of a narrow band of noise (the pointer) so that it matched the intracranial position of a second, experimenter-controlled, stimulus (the target). Targets were sinusoidally-amplitude-modulated tones with carrier frequencies chosen at octave intervals between 500 Hz and 4 kHz. Rates of modulation ranged from 50 Hz and 400 Hz, and each target contained interaural temporal disparities and/or interaural intensitive disparities. In contrast to the findings from several recent investigations, the data strongly suggest that interaural temporal disparities in the envelope (modulator) affect the lateral position of low-frequency targets. These envelope-based cues appear to interact with those provided by the fine-structure, which appear to be dominant. In addition, interaural temporal disparities in the fine-structure of low-frequency targets appear to be more potent than interaural temporal disparities in the envelope, regardless of the spectral locus of the target. No consistent relation was found between the extent of laterality produced by an interaural intensitive disparity and the spectral locus of the target. Finally, we observed consistent individual differences in how the listeners weighted cues provided by the fine-structure and the envelope. All of these findings suggest that the localization of complex, dynamically changing sounds depends upon several factors and is not well characterized by traditional experiments which employed only pure tones of stimuli.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Bernstein, Leslie Robert

• Psychology, Experimental

Identifier

(UMI)AAI8422020

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/69645