Master of Arts (MA)


Communication Sciences and Disorders

Document Type



The present research involves two studies. Twenty hearing-impaired participants were divided into two groups depending on their audiometric data and binaurally fit with the Starkey Endeavour 3211 hearing instruments. Experiment I was designed to determine if the use of expansion technology affected objective and subjective benefit in hearing-impaired listeners. Probe microphone measures were obtained at 40, 50, and 60 dB SPL and with the speaker deactivated to ensure that the expansion feature was functioning. Listener performance was measured in quite using the Connected Speech Test (CST) and in noise using the Hearing in Noise Test (HINT) at 40, 50, and 60 dB SPL with expansion activated and deactivated. Participants were also asked to participate in a subjective portion of the experiment. They filled out a rating form twice a day in two settings: quiet and in noise, with expansion activated and deactivated. Results indicated that expansion negatively affected user performance, but participants significantly preferred the feature. Experiment II, very similar in design, examined expansion time constants and their effects on objective and subjective benefit in hearing-impaired listeners. Experiment II examined four different expansion time constants (128 ms, 512 ms, 2048 ms, 4056 ms) to determine their role on speech intelligibility in quiet and in noise with two levels of hearing-impaired subjects (one group was worse than the other). The CST and the HINT were administered at 65 dB SPL to determine listener performance. A similar subjective rating form was used in Experiment II. Participants were asked to rate the speed of the gain and/or reduction of gain in quiet and in noise while speaking and listening. Results indicated that as expansion time constants lengthened performance decreased. Results indicated that there was no preferred time constant and that as the time constant lengthened performance decreased.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Paul Hoffman