Importance: Less than 20% of US adults with hearing loss use hearing aids due to barriers like high cost. Over-the-counter (OTC) hearing aids offer a potential solution, incorporating self-fitting strategies via smartphone apps. Self-fitting strategies have been validated for FDA-approved OTCs compared to prescription-based approaches. However, no direct comparative analysis exists between in-situ audiometry and self-adjustment strategies using self-fitting OTC (OTC-SF) hearing aids.

 Objective: To compare self-adjustment and in-situ audiometry self-fitting strategies in OTC-SF hearing aids for adults with mild-to-moderate hearing difficulties.

 Design Settings and Participants: A cross-over, within-subject pseudo-randomized controlled trial was conducted between July and November 2023. Twenty-eight participants were pseudo-randomly assigned to one of the two self-fitting strategies, and they experienced both interventions for four consecutive weeks.

Interventions: The self-adjustment group manually adjusted settings, including overall gain and spectral tilt, using Lexie B2 hearing aids, while the in-situ audiometry group utilized Lexie B2 Plus hearing aids, with an automated fitting based on in-situ tests conducted through the app.

 Main Outcomes and Measures: Primary outcome: Abbreviated Profile of Hearing Aid Benefit (APHAB). Secondary outcomes: International Outcome Inventory for Hearing Aids (IOI-HA), speech-in-noise tests (DIN and QuickSIN), and real-ear measurements (REMs). Measures were completed at baseline and after the four-week field trial using each strategy.

 Results: Twenty-eight participants (mean age 60.2 years SD 12) were evenly distributed by sex. Self-adjustment and in-situ audiometry strategies produced no clinically meaningful differences across various outcome measures, including overall APHAB benefit (Cohen d = 0.2 [95% CI, -0.2 – 0.6]) and overall IOI-HA satisfaction (Rosenthal’s r = 0.0 [95% CI, -0.3 – 0.2]). Self-adjustment users reported higher satisfaction (Rosenthal’s r = -0.4 [95% CI, -0.6 – -0.1]) and longer daily use (Rosenthal’s r = -0.3 [95% CI,-0.5 – 0.0]) compared to those utilizing in-situ audiometry. No clinically meaningful differences were observed in speech-in-noise benefit and real-ear measurements.

 Conclusion and Relevance: For OTC-SF hearing aids, self-adjustment and in-situ audiometry strategies resulted in similar outcomes. However, self-adjustment may produce higher satisfaction and longer daily use, highlighting the potential advantages of active user involvement in the fitting process. Further investigation is needed for long-term outcomes.