Can real-ear insertion gain deviations from generic fitting prescriptions predict self-reported outcomes?

Listening Preferences of New Adult Hearing Aid Users: A Registered, Double-Blind, Randomized, Mixed-Methods Clinical Trial of Initial Versus Real-Ear Fit

“…For example, 20% of custom earmold initial fittings were within 10 dB of target in Munro et al (2016) compared to 67% in the current study. Similar improvements in the manufacturers’ initial fits were also observed in recently published studies that found small initial fit deviations from targets and greater consistency between manufacturers (Folkeard et al, 2019; Narayanan et al, 2022).…”

“…The findings of this study could be generalized to other prescription methods, given the similarity between prescription methods (Johnson & Dillon, 2011) and the lack of noticeable deviations of initial fits from targets that were found with the Desired Sensation Level prescription method (Folkeard et al, 2019). However, caution should be exercised when generalizing the results of this experiment to other manufacturers’ fitting software, as there are mixed reports of deviation from target values (Narayanan et al, 2022; Sanders et al, 2015). In addition, it is unclear whether the findings can be generalized to other types and severities of hearing loss.…”

“…In earlier reports, manufacturer's initial fit was found to provide inadequate amplification compared to Real Ear Measurement (REM) fitting, with deviations between the two approaches most prominent at high frequencies and low input levels (Aazh & Moore, 2007; Aazh et al, 2012; Munro et al, 2016; Sanders et al, 2015; Valente et al, 2018). However, accuracy of the manufacturer's initial fits has improved over time (Folkeard et al, 2019; Narayanan et al, 2022), presumably because (a) hearing aids have become more adjustable and (b) manufacturers have more information about how to allow for low-frequency venting and high-frequency tubing effects (Dillon, 2012). For example, Aazh and Moore (2007) found that only 36% of initial fittings were within 10 dB tolerance of NAL-NL1 target from 0.5 to 4 kHz.…”

“…Based on the findings of our review, it is evident that there is a need for high-quality evidence on clinical and cost-effectiveness of REM, given that it requires resources and time (perhaps up to ten minutes of a typical NHS fitting appointment), which could be otherwise directed to non-technical procedures such as addressing the specific listening needs of the patient. In addition, the accuracy of the manufacturers’ initial fit, as mentioned above, has improved over time (Folkeard et al, 2019; Narayanan et al, 2022). However, a lack of statistically significant gain difference between the REM and initial fittings would not mean patients will not have a preference for either of the fitting approaches.…”

“…More recent studies have reported further improvement in the manufacturer's initial fits. For example, Narayanan et al (2022) reported data from 1251 participants fitted with seven different hearing aid brands. They found that the median initial fit deviation from the NAL-NL2 targets was around zero at all frequencies except 4 kHz.…”