| Summary: | The purpose of the present study was to determine whether amplifying beyond 3 kHz was beneficial to the user, whether the benefit was dependent on degree of loss, and whether subjective data reflected the benefit. Seventeen hearing impaired subjects were binaurally fitted with digital hearing instruments. Qualified subjects were divided into two groups, A and B. Group A had a pure tone average (3,4, and 6 kHz), of 55 dBHL or better. Group B had a pure tone average (3,4, and 6 kHz) greater than 55 dBHL but not exceeding 75 dBHL. Each subject was fit with two conditions (upward frequency response of 3 kHz and 6 kHz) throughout the study. Probe microphone measurements were obtained at the plane of the tympanic membrane using a swept pure tone of 60 dB SPL to verify appropriate fit of the hearing instruments. Listener performance in quiet was evaluated via the Connected Speech Test (CST), listener performance in noise was evaluated via the CST and the Hearing in Noise Test, and listener preference was evaluated via the Abbreviated Profile of Hearing Aid Benefit and an exit questionnaire. Results of the probe microphone measures indicated that the mean output levels for each condition were significantly different. Results indicated that increasing the bandwidth did not significantly improve benefit in quiet for either group but did significantly improve benefit in noise for each group. However, the amount of benefit was similar for each bandwidth suggesting that the amount of benefit is not dependent on degree of loss. Subjective data suggested that amplifying beyond 3 kHz did not increase subjective benefit according to the APHAB. However, results from the exit questionnaire suggest that the 6 kHz condition was preferred by the majority of the subjects overall, both in quiet and in noise.
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