Hearing loss among workers at an oil refinery in Taiwan

In this study, the authors determined the characteristics of noise-induced hearing loss (NIHL) and its association with hearing-loss-related symptoms (HLRSs) among workers at an oil refinery in Taiwan. Workers from the refinery (N = 384) who had chronic noise exposure (range = 73 to 89 dBa; mean = 81.2, standard deviation = 5.4 dBa) were enrolled in the study. Workers chronically exposed to noise levels that were less than 85 dBa experienced slight hearing loss at high frequencies [(3k + 4k + 6k)/3]. Workers with > or = 1 HLRSs had increased hearing loss at low frequencies [(0.5k + 1k + 2k)/3] and high frequencies (odds ratios = 7.2 and 3.7, respectively). An increased hearing threshold shift for high frequencies (3k, 4k, and 6k Hz) was found in workers who had chronic noise exposure for more than 15 yr. These findings indicate that self-reported HLRSs provide valuable early warning signs of NIHL.