Technology-limited and patient-derived versus audibility-derived fittings in bone-anchored hearing aid users: a validation study.

OBJECTIVES: Current approaches to fit bone-anchored hearing aid (Baha) rely heavily on patient feedback of "loudness" and "sound quality." Audiologists are limited to this approach for two reasons: (1) the technology in current models of Baha does not allow for much fine-tuning of frequency response or maximum output on an individual basis and (2) there has not been a valid approach to verify the frequency response or maximum output on an individual basis. The objectives of this study are to (1) describe an alternative approach to fit Baha, an "audibility-derived (AD)" fitting, and (2) test whether outcomes improve with this new fitting compared with the current "patient-derived (PD)" fitting. DESIGN: This study used a repeated measures design where each subject experienced both the AD and PD fittings in random order. Subjects were tested on a variety of outcome measures including output levels of aided speech, hearing in noise test (quiet and in noise), consonant recognition in noise, aided loudness, and subjective percentage of words understood. RESULTS: Electromechanical testing revealed significantly higher aided output with the AD fitting, especially in the high frequencies. Subjects performed significantly better in all outcome measures with the AD fitting approach except when testing aided loudness and subjective perception for which the differences were nonsignificant. When the input levels to the Baha were soft, advantages for the AD fitting were emerging on these tests, but they did not reach significance. CONCLUSIONS: This study presents a more objective, fitting approach for Baha that leads to better outcomes in the laboratory. The next steps will be to test these fittings in the real world and to make the approach generally available to clinicians fitting Bahas.