Date of Award

Spring 1-1-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Speech, Language & Hearing Sciences

First Advisor

Kathryn H. Arehart

Second Advisor

James M. Kates

Third Advisor

Phillip Gilley

Fourth Advisor

Lewis Harvey

Fifth Advisor

Anu Sharma

Abstract

Music perception with hearing aids has recently gained attention as a clinical and scientific problem. The goal of this dissertation was to examine the roles of input-signal properties, hearing-aid processing, and individual variability in the perception of recorded music. Two experiments considered music-industry compression limiting (CL) and hearing-aid wide dynamic-range compression (WDRC). The specific aims were: 1) to characterize the acoustic effects of CL on recorded music and to determine how listeners with normal hearing perceive recorded music processed by CL, 2) to quantify the acoustic and perceptual effects of CL, WDRC, and CL+WDRC on recorded music processed through simulated hearing aids, and 3) to examine the relationship between preferred compression parameters and individual perceptual characteristics of listeners with hearing loss.

Experiment 1 investigated the effects of CL on classical and rock music. An acoustic analysis indicated reduced fidelity with increasing compression. When loudness varied due to compression, normal-hearing listeners preferred mild CL, on average. When loudness was equalized, mild compression did not affect music quality, but heavier compression was less preferred. Responses varied among individual listeners.

Experiment 2 evaluated CL+WDRC using hearing-aid simulations and listeners with hearing loss. Acoustically, WDRC diminished amplitude contrasts and upset spectral balance, particularly for conditions with more channels (18 vs. 3) and a faster release time (50-msec vs. 1000-msec). Perceptually, linear processing and slow WDRC were equally preferred over fast WDRC for classical music. For rock music, linear processing was preferred to both slow and fast WDRC. The main effect of channels was not significant for classical music, but for rock, 3-channel processing was preferred. CL degraded music quality for classical but not for rock. For classical music, listeners with broader estimated auditory filters preferred 3 channels and linear processing, while listeners with narrower filters preferred 18 channels and slow WDRC. For rock music, the degree of preference for linear processing was greater for listeners with a larger dynamic range. The present findings have highlighted specific acoustic modifications that contribute to music quality and have identified compression parameters that are perceptually relevant for both music-industry recording and hearing-aid design.

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