Cortical Indices of Auditory Processing of Speech in Reverberation

Date of Award

2008

Document Type

Dissertation

Degree Name

Doctor of Science (ScD)

College/School

College of Humanities and Social Sciences

Department/Program

Communication Sciences and Disorders

Thesis Sponsor/Dissertation Chair/Project Chair

Janet Koehnke

Committee Member

Ilse Wambacq

Committee Member

Joan Besing

Abstract

A common complaint of listeners is difficulty perceiving speech in everyday listening environments that contain background noise and reverberation. In this study, we measured auditory event-related potentials (ERPs) to determine the effect of noise and reverberation on speech perception in young and older listeners with normal hearing. The components Nl, P2, and P3 were examined. To our knowledge, there have been no ERP studies examining the effects of reverberation on speech perception. An active oddball paradigm was used in which listeners pressed a button to indicate the speech sound they heard. Stimuli were CV tokens /ba/, /da/, and /ga/. These tokens were selected based on a preliminary study designed to determine the most appropriate speech stimuli from a closed set of stop consonants followed by the vowel /a/. The listening conditions included speech: (1) plus noise (+12 dB SNR) without reverberation, (2) plus noise (+12 dB SNR) with 0.31s of reverberation, and (3) plus noise (+12 dB SNR) with 0.63s of reverberation. Results indicate that the ERP components were affected by the addition of reverberation to background noise in young adults. This is in agreement with existing behavioral data which show that as the listening condition becomes more degraded (by noise and reverberation), less information is accurately perceived by the listener. In older adults, we did not find a significant effect of reverberation. In all listening conditions the ERP responses in older adults were reduced compared to the ERPs in young adults.

Comments

Print version available at Sprague Library.

Full text available at ProQuest Dissertations & Theses Global

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