[Analysis of asymmetric hearing loss in both ears of patients with occupational noise-induced deafness]

Objective: To investigate the characteristics of asymmetric hearing loss in left and right ears of patients with occupational noise-induced deafness and to explore the possible causes of asymmetric hearing loss. Methods: A total of 423 cases of occupational noise-induced deafness diagnosed in Guangdong Province Hospital for Occupational Disease Prevention and Treatment from May 2015 to May 2018 were investigated retrospectively. On the basis of three consecutive pure tone audiometry (PTA) with intervals of more than 3 d in hospital, the minimum of hearing threshold of each frequency and the frequency response threshold of auditory steady-state response (ASSR) , and based on the GBZ 49-2014 "Diagnosis of Occupational Noise-induced Deafness". The statistical analysis of Wilcoxon signed rank test and Spearman correlation analysis were carried out by nonparametric test. The hearing threshold weight of PTA and the response threshold of ASSR were tested and compared from different dimensions according to sex, age, length of service of exposure noise, diagnosis grade and so on. Results: There were 369 male (87.23%) and 54 female (12.77%) ; the age was (41.8±7.6) years; the length of service was (10.1±6.2) years. The weighted values of left ear PTA and ASSR were higher than those of right ear (P<0.001) . The weighted values of left ear PTA and ASSR were higher than those of right ear (P<0.05) in men, patients with age ≤ 40 and 41-60 years, 3-9 years of service, and patients with mild grade (P<0.05) . After the equalization of characteristic variables, the weighted values of left ear PTA and ASSR were also higher than those of right ear (P<0.05) . There was a positive correlation between the weighted value of PTA and the weighted value of ASSR (P<0.001) . Conclusion: There is asymmetry in hearing loss of patients with occupational noise deafness, and hearing loss in the left ear is higher than that in the right ear.