ABSTRACT
Objective To investigate the correlation between incidence rate of tinnitus and noise exposure time,age,hearing condition in noise exposure workers.Methods A total of 1 985 noise exposure workers (age between 20～60 years old;working length between 1 ～30 years) in a large dockyard were randomly selected as the subject of this study with 1 831 male workers and 154 female workers in average 36.3±8.25 years old.The average noise exposure time was 9.1±6.50 years and pure tone threshold of final candidates in sound-proofed environment was evaluated (at 0.25～8 kHz).The subjects were divided into four groups according to the subjective tinnitus level:mild tinnitus,moderate tinnitus,severe tinnitus and no tinnitus to analysis the correlation among incidence rate of tinnitus and noise exposure time,age,hearing condition,etc.Results Among all 1 985 subjects enrolled the occurrence rate of tinnitus was 20.55％ (408/1 985),with 367 acquired mild tinnitus(89.95％),39 acquired moderate tinnitus (9.56％) and 2 for severe tinnitus (0.49％).Mild tinnitus and moderate tinnitus showed a multi-step raising according to noise exposure time.Mild tinnitus increased continually with age while moderate tinnitus showed an accumulation in age group over 55 years old.Female was less likely to be annoyed by tinnitus than male.Conclusion Tinnitus can be early warning of auditory damage by noise exposure;older male group with longer noise exposure time is more vulnerable to tinnitus.Tinnitus acquired in noise environment is more likely to be mild.