Comparison of a Hearing Aid Fitting Formula Based on Korean Acoustic Characteristics and Existing Fitting Formulae

Abstract

Purpose: Most existing hearing aid (HA) fitting formulae were developed based on English. However, Korean language has different acoustic characteristics compared to English. This study aimed to develop Korean language-specific hearing aid fitting formula (Hallym Audiology Institute-version 1, HAI-v1) and to compare speech perception, clarity, and overall preference between the HAI-v1 and established fitting formulae [National Acoustic Laboratories’ nonlinear fitting procedure, version 2 (NAL-NL2) and Desired Sensation Level, version 5.0 (DSL5.0)]. Methods: Gains for the HAI-v1 were determined to reach the gain around the medium to the two-thirds portion in the dynamic range of conversational speech level for soft, medium, and loud levels using loudness growth for Koreans who have sensorineural hearing loss (SNHL). Twenty-four people with SNHL participated in this study. Reception thresholds of sentences (RTSs) and preferences (clarity and overall preference) were evaluated, once with HAI-v1 setting, once with NAL-NL2 setting, and once with DSL5.0 setting, in random order. Then, results of RTSs and preferences across HA fitting formulae were compared. Results: There were no statistical differences for RTSs with and without noise in all HA fitting formulae. For clarity, more participants preferred sounds with HAI-v1 or NAL-NL2 than sounds with DSL5.0. For overall preference, more participants preferred sounds with HAI-v1 than sounds with NAL-NL2 or DSL5.0. Conclusion: Results of this study suggest that language-specific HA fitting formula may provide better HA outcomes for people who use different languages.