Prevalence of hearing impairment in an adult population in Southern Taiwan.

The objective of this study was to estimate the prevalence of hearing impairment in a representative adult population in southern Taiwan and compare the results to those of similar studies in other countries. A stratified systematic cluster sample of 1140 residents, aged > or =20 years, of Tainan City was studied from 2001 to 2003. The test battery included otoscopy, pure-tone audiometry, and a questionnaire covering relevant personal, occupational, and family history. The hearing threshold level (HTL) was defined as the better ear pure-tone average (BPTA) (i.e. the average of hearing thresholds at frequencies 500, 1000, 2000, and 4000 Hz). The prevalence of hearing impairment was 21.4% (95% confidence interval: 19.3-23.7%) at BPTA > or =25 dB HTL. Middle ear disease was a significant risk factor for hearing impairment in addition to age and gender. The overall prevalence of hearing impairment may be higher in Taiwan (17.1%) than in western populations (11.5%), but differences in the definition of hearing impairment severity and variation in sex distribution among studies may account for this higher prevalence.