Prevalence of asymmetric hearing loss in Korean adults

BACKGROUND: Representative data on asymmetric hearing loss (AHL) in Korea remain limited. AIMS/OBJECTIVES: To estimate AHL prevalence among Korean adults aged ≥40 years and characterize age-standardized prevalence, frequency-specific asymmetry, laterality, and interaural difference (IAD) distribution. MATERIAL AND METHODS: Data from the 2022-2023 Korea National Health and Nutrition Examination Survey were analyzed. Adults aged ≥40 years with complete bilateral pure-tone audiometry and type A or type C tympanograms were included. AHL was defined as an absolute IAD ≥15 dB HL in the four-frequency pure-tone average. Weighted analyses accounted for the complex sampling design. RESULTS: Among 6,574 participants, 447 had AHL. Weighted prevalence was 6.5% (95% confidence interval [CI], 5.9-7.2%), and directly age-standardized prevalence was 6.0% (approximate 95% CI, 5.3-6.6%). Prevalence increased from 3.2% at 40-49 years to 11.9% at ≥80 years. Older age and male sex were independently associated with AHL; occupational noise exposure was not. Frequency-specific asymmetry was most common at 4 kHz. Among AHL cases, left-sided AHL predominated, and IADs were concentrated near the lower end of the diagnostic range. CONCLUSIONS AND SIGNIFICANCE: AHL increased with age and showed high-frequency and left-sided predominance. These findings provide population-based reference data and support cautious interpretation of criterion-defined AHL.