By Ghenwa Bou Mrad, student of the Master in Clinical Audiology and Hearing Therapy

Abstract

Advances in digital signal processing (DSP) have added remarkable into modern hearing aids (HAs), yet patients continue to report difficulties in speech-in-noise perception and listening effort to date. The three leading manufacturers, Unitron, GN ReSound, and Oticon, represent distinct philosophies when addressing these challenges. Unitron emphasizes automatic environment classification, GN ReSound focuses on connectivity and binaural coordination, and Oticon adopts an open-sound paradigm. This narrative review synthesizes comparative evidence on these approaches, highlighting their technical foundations, clinical outcomes, and limitations. Results suggest that while laboratory measures of speech-in-noise performance remain central, patient-reported satisfaction depends equally on ecological validity, personalization, and reduced listening effort. The review concludes that future hearing aids may integrate hybrid strategies combining environment classification, connectivity, and open sound, optimized by artificial intelligence (AI).

Keywords: hearing aids, signal processing, speech in noise, cognitive load, ecological validity, hearing aid manufacturers.

Download the full Research Work: Bou Mrad, G (2025). Comparative Literature Review of Signal-Processing Strategies in Hearing Aids Unitron, GN ReSound and Oticon. SAERA