Normative Hearing Threshold Levels in Koreans with Normal Tympanic Membranes and Estimated Prevalence of Hearing Loss

ABSTRACT

OBJECTIVES: We investigated the normative data on the hearing threshold levels of Koreans with normal tympanic membranes and the prevalence of hearing loss (HL) and nonserviceable hearing using the data from the Korea National Health and Nutrition Examination Surveys (KNHANES) during 2010–2012. METHODS: Data obtained from 16,673 participants ≥12-year-of-age with normal tympanic membranes who completed audiometric testing. We defined HL as the pure tone average (PTA) >25 dB hearing level at 500, 1,000, 2,000, and 3,000 Hz and non-serviceable hearing as PTA >40 dB hearing level. RESULTS: The hearing levels at some frequencies (0.5, 3, and 6 kHz) did not differ in between the 10's and 20's, but the hearing thresholds at all frequencies increased gradually from the 30's. The hearing thresholds were higher in men than in women at high frequencies (3, 4, and 6 kHz) in the 30's and older. The prevalence of HL in either ear was 16.5% (estimates of 5.9 million), from 2.4% in the 10's up to 75.4% in the 70's and older. The prevalence of nonserviceable hearing in either ear was 6.8% (estimates of 2.5 million) and that of bilateral nonserviceable hearing was 2.5% (estimates of 0.9 million). CONCLUSION: Hearing loss aggravated from the 30's at all frequencies and men showed poorer hearing levels than women at high frequencies. Hearing loss was a common condition and the prevalence of non-serviceable hearing in either ear, which needs hearing rehabilitation to help social communication, was 6.8%. Normative pure tone thresholds at each frequency can be used as referent values when counseling patients complaining of hearing loss.