Go Figure: Customizing Gain Leads in Optimal Results

This installment of Go Figure shows results of a 2018 study from Mike Valente’s lab at Washington University in St. Louis. Using a double-blind, randomized crossover design 24 adult participants with mild-moderate, downward-sloping bilateral hearing loss were fitted with hearing aids for the first time. The 24 participants were split into two groups: One fitted to a closely matched NAL-NL2 prescriptive target and verified with standard probe microphone measures, and the other group fitted to the manufacturer’s proprietary first-fit algorithm without probe microphone verification measures.

All 24 participants wore the hearing aids for about three weeks. Following this time frame, they returned for follow-up testing, including speech recognition in quiet and in noise (HINT), subjective responses for the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Speech, Spatial and Qualities of Hearing (SSQ) questionnaire.

The group fitted to the NAL-NL2 target and verified with probe microphone measures outperformed the “first-fit” group on all outcome measures. Perhaps the most fundamental point taken from the study is outlined in the figure. It shows the group fitted and verified to the NAL-NL2 target had almost 20% better, on average, speech recogition scores relative to the “first fit” group.

If you are wondering if it’s worth the time to chase after five to ten dB of gain in the ear canal (and not simply rely on first-fit algorithms), the results of this study clearly show that, yes, it is worth the time to customize gain. Getting closer to the prescribed target is likely to achieve significantly better speech recognition ability for most patients.

You can find the complete article here:

Valente M., Oeding K., Brockmeyer A., Smith S., and Kallogjeri D. (2018) Differences in Word and Phoneme Recognition in Quiet, Sentence Recognition in Noise, and Subjective Outcomes between Manufacturer First-Fit and Hearing Aids Programmed to NAL-NL2 Using Real-Ear Measures. J Am Acad Audiology 29, 8, 706-721.