Date of Award


Degree Type


Degree Name

Master of Science


Health and Rehabilitation Sciences


Dr. Susan Scollie


Speech intelligibility and quality scores were evaluated across four different hearing aid settings that differed in the strength of directional microphone (DM), digital noise reduction (DNR), and level dependent speech enhancement (LDSE) features, in quiet and noise, and in low and high reverberation environments. Twenty-two listeners with bilateral sensorineural hearing loss and ten normal hearing listeners participated in our study. Results indicated that the directional microphone condition provided significant improvement for speech recognition in noise, at both levels of reverberation. Addition of SE and DNR processing to directional microphone had both beneficial and detrimental effects on speech perception and sound quality depending upon the strength of processing, type of environment, and noise condition. Specifically, SE and DNR features operating at maximum strength degraded speech intelligibility in the high reverberation environment. The same processing condition was, however, rated as having higher sound quality especially when the masker was stationary noise at 0 dB signal to noise ratio in low reverberation. Clinical implications of these results are discussed.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.