Date of Award

Summer 2019

Document Type

Open Access Dissertation


Communication Sciences and Disorders

First Advisor

Daniel Fogerty


Amplification is necessary to restore audibility to individuals with hearing impairment. However, frequency-specific amplification alters the spectral shape and level of speech. Previous research has demonstrated that amplification is associated with better speech recognition outcomes as compared to unaided listening (e.g. Humes, 2013). However, many hearing aid listeners report a lack of perceived benefit associated with hearing aids, and adherence is low (McCormack and Fortnum, 2013). This may, in part, be reflected by a common complaint of hearing aid users that speech is audible, but additional effort is required to understand speech. As amplification alters the spectral shape and overall level of speech, it is possible that more effort could be required to understand amplified speech, even in situations where accuracy remains equivalent. Furthermore, previous research has suggested that ratings of perceived sound quality differ with various hearing aid processing techniques (Neuman et al., 1998). Therefore, it is possible that varying spectral shape and speech level could have effects on perceived sound quality as well. This has clinical implications, as poor perceived sound quality is a top complaint of hearing aid users (McCormack and Fortnum, 2013). The current study aimed to systematically investigate the effect of spectral shape and speech level on measures of speech recognition, listening effort, and sound quality. Outcomes were investigated in three different background conditions. In addition, acoustic metrics were utilized to quantify the alterations made to speech stimuli amplified in a frequency-specific manner.