Preferred Name

Molly Scherer

Date of Award

Spring 2017

Document Type

Dissertation

Degree Name

Doctor of Audiology (AuD)

Department

Department of Communication Sciences and Disorders

Advisor(s)

Christopher G. Clinard

Brenda M. Ryals

Lincoln C. Gray

Abstract

Difficulty understanding speech in the presence of background noise is one of the most common complaints of older adults, both with and without hearing loss. One possible contributing factor is an age-related decline in neural synchrony (e.g., phase locking). Tones-in-noise were used in an attempt to disrupt rate-place coding of frequency and to encourage participants to use phase-locked, temporal representations of frequency during a behavioral frequency discrimination task. Fourteen adults participated in the study (five younger, aged 21-29; four middle aged, 41-50; and five older, aged 61-80). Participants had clinically normal hearing sensitivity (≤ 25 dB HL at octave frequencies 250 – 8000 Hz). Tone-in-noise detection thresholds and frequency discrimination limens (FDLs) were obtained at 500 and 1000 Hz, separately. FDLs were tested in quiet and noise conditions. The Words-in-Noise test was used to assess speech-in-noise understanding. Results indicated that tone-in-noise detection thresholds were not significantly different across age groups. Frequency discrimination limens were significantly poorer (larger) in the presence of noise; however, no significant age effects were found. Frequency discrimination results indicated that the presence of noise worsened FDLs, consistent with the effect expected with reduced neural coding strategies available in noise. Speech-in-noise understanding was not significantly different across age groups. It is believed that the presence of noise may reduce the effectiveness of some neural coding strategies available to listeners.

Available for download on Wednesday, February 13, 2019

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