Publication Date


Document Type


First Advisor

Sandridge, Sharon A.||Jackson, Pamela L.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Communicative Disorders


Hearing aids


Three widely used prescriptive methods of hearing aid selection, the NAL, the POGO, and the CID Phase IV method were compared on the basis of prescribed gain, listener quality judgement and speech intelligibility. Fourteen adult subjects with acquired sensori-neural hearing losses no poorer than moderate-to-severe and fit with behind-the-ear amplification for a minimum of three months were tested with the Telex 353C behind-the-ear hearing aid coupled to their own earmold. Testing was completed over two sessions. Session 1 consisted of pure-tone threshold testing, obtaining most comfortable loudness levels (MCL) and uncomfortable loudness levels (UCL) for pulsed tones, and then unaided sound-field thresholds. Session 2 consisted of assessing each prescriptive method where the order of testing followed the same three step procedure. Step 1: The Telex 353C was set to provide the gain determined by the prescriptive method. The real ear insertion response was obtained. Modifications of tone control and SSPL90 were made to obtain the "best fit" curve. Step 2: The quality of speech with the aid set to that particular prescribed gain was then determined. A commercially recorded connected discourse (male talker) was presented at 55 dBHL. The subject was asked to rate the quality using eight adjectives. An overall quality rating was also obtained by rating the quality on a scale of 1 (poor) to 5 (excellent). Step 3: Speech intelligibility was then assessed by presenting the same connected discourse in the presence of an ipsilateral speech noise through the speaker. The speech was held constant at 55 dB HL and the noise was varied in intensity. The subject was instructed to indicate when he/she believed the speech to be approximately 50% intelligible. The prescribed gain, the rating for quality and the signal-to-noise ratio for each method were statistically analyzed. No significant difference for any variable was found, suggesting that the actual procedure used is not the critical issue in hearing aid selection. Follow up and counseling in assisting the hearing-impaired individual in the use of hearing aids is perhaps one of the most important factors in a good hearing aid fitting.


Includes bibliographical references (pages 44-47)


69 pages




Northern Illinois University

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