A "Goldilocks" Approach to Hearing Aid Self-Fitting: Ear-Canal Output and Speech Intelligibility Index.

OBJECTIVES

The objective was to determine self-adjusted output response and speech intelligibility index (SII) in individuals with mild to moderate hearing loss and to measure the effects of prior hearing aid experience.

DESIGN

Thirteen hearing aid users and 13 nonusers, with similar group-mean pure-tone thresholds, listened to prerecorded and preprocessed sentences spoken by a man. Starting with a generic level and spectrum, participants adjusted (1) overall level, (2) high-frequency boost, and (3) low-frequency cut. Participants took a speech perception test after an initial adjustment before making a final adjustment. The three self-selected parameters, along with individual thresholds and real-ear-to-coupler differences, were used to compute output levels and SIIs for the starting and two self-adjusted conditions. The values were compared with an NAL second nonlinear threshold-based prescription (NAL-NL2) and, for the hearing aid users, performance of their existing hearing aids.

RESULTS

All participants were able to complete the self-adjustment process. The generic starting condition provided outputs (between 2 and 8 kHz) and SIIs that were significantly below those prescribed by NAL-NL2. Both groups increased SII to values that were not significantly different from prescription. The hearing aid users, but not the nonusers, increased high-frequency output and SII significantly after taking the speech perception test. Seventeen of the 26 participants (65%) met an SII criterion of 60% under the generic starting condition. The proportion increased to 23 out of 26 (88%) after the final self-adjustment. Of the 13 hearing aid users, 8 (62%) met the 60% criterion with their existing hearing aids. With the final self-adjustment, 12 out of 13 (92%) met this criterion.

CONCLUSIONS

The findings support the conclusion that user self-adjustment of basic amplification characteristics can be both feasible and effective with or without prior hearing aid experience.