Considerations for fitting, programming, and verification of sound therapy delivered by hearing aids

Objective Identification of fitting and programming considerations for sound therapy in hearing aids based on electroacoustic characterization across brands, including assessment of interactions between sound therapy and other digital signal processing (DSP) features. Methods The study was conducted in two parts: (1) electroacoustic characterization of default sound therapy settings, and (2) analysis of interactions between the sound generator, feedback cancellation, and noise reduction features. Five receiver-in-the-ear hearing aids from different manufacturers were assessed using the Ahead Simulations Clinical Assistant for Research and Learning (CARL) manikin and the Audioscan Verifit 2 hearing aid analyzer. Devices were programmed for two standard audiograms using both dome and custom earmold couplings. Results Default sound therapy outputs varied significantly across brands, influenced primarily by audiogram and coupling type. Feedback testing revealed that enabling sound therapy caused devices to exceed their stable gain limits, resulting in audible feedback. Noise reduction algorithms reduced sound therapy signals in open-fit configurations. Conclusions Sound therapy features differ across hearing aids and can interact with other DSP functions counterproductively. These interactions are measurable using standard clinical verification tools, highlighting the importance of verification of hearing aid programs. Five clinical fitting practices were developed to address these considerations.