Objective To study the expression of Nuclear factor E2 related factor 2 (Nrf2) ,Superoxide Dis‐mutas 1 (SOD1) ,and Heme Oxygenase- 1( HO -1) factors related to Nrf2 signaling pathway in noise-induced cochlear injury of rats .Methods A total of 30 SD rats were randomly and equally assigned into the following 2 groups :noise group and normal control group .The rats in noise group were exposed to an 115 dB SPL continuous steady white noise for 12 hours ,then 1 day ,3 days ,and 7 days later ,the rats receveid the ABR and DPOAE testing after noise exposure .Both RT -PCR and Peggy Sue trace protein detection techniques were used to detect gene ex‐pression in Nrf2 /Keapl-ARE signaling pathway and the protein levels by cochlear tissue sampling after noise ex‐posure 7 days later .Results The ABR thresholds in the noise group was higher than those of in normal control group after noise exposure 1 ,3 ,and 7 days later (P<0 .05) .The DPOAE values of noise group were significantly lower than those of normal control group (P<0 .05) .The up -regulation of expression of Nrf2 ,SOD1 ,HO -1 mRNA(1 .11 ± 0 .05 ,1 .45 ± 0 .12 ,1 .15 ± 0 .03) in noise group were higher than those of in the normal control group after noise exposure 7 days later (1 .00 ± 0 .02 ,1 .10 ± 0 .12 ,0 .92 ± 0 .08) ,and the differences were statistically sig‐nificant (P<0 .05) .And in Peggy Sue trace detection system ,we also found SOD1 ,HO -1 protein levels in noise group were higher than those of in normal control group .Conclusion After the noise -induced cochlear injury in rat ,Nrf2 expression in the cochlea increased and up-regulatd expression of downstream gene and protein content such as antioxidant enzymes SOD1 and HO-1gene by regulating Nrf2 /Keapl-ARE signaling pathway ,which may be involved in protection against oxidative stress injury in noise-induced cochlear injury of rat .

Objective To investigate the features of hearing loss induced by ship noise among sailors.Methods One thousand sailors,among whom 563 of them were from the deck department and 437 were from the engine department,received hearing tests.Results Of pure tone audiometry detection were evaluated,analyzed and compared.Results For hearing damage at various frequencies,hearing loss at 4 kHz was the most common.The rate of hearing loss at high frequency was greater than that at audio frequency,which conformed to the features of noise-induced hearing loss (NIHL).The longer the sea service of sailors was and the longer they exposed to ship noise,the greater hearing damage they would sustain.For instance,the rate of hearing loss for sailors with 31 years of sea service or longer would reach as high as 35.2％.Statistical differences could be seen in the severeness of hearing damage among different groups of sailor with different length of sea service (P ＜ 0.01).There was statistical significance in the rate of hearing loss,when comparisons were made between the engine department sailors (21.1％) and the deck department sailors (11.4％) (P ＜ 0.01).The rate of hearing loss for the sailors wearing ear plugs frequently was much lower than those not wearing them,also with statistical significance (P ＜ 0.01).Conclusions Due to the high rate of hearing loss among sailors,the application of ear plugs could alleviate noise-induced hearing loss to some extent.It is of practical importance to develop and adopt highly effective,convenient and nontoxic intervention measures or devices against noiseinduced hearing loss.

Objective To investigate the features of hearing loss induced by ship noise among sailors.Methods One thousand sailors,among whom 563 of them were from the deck department and 437 were from the engine department,received hearing tests.Results Of pure tone audiometry detection were evaluated,analyzed and compared.Results For hearing damage at various frequencies,hearing loss at 4 kHz was the most common.The rate of hearing loss at high frequency was greater than that at audio frequency,which conformed to the features of noise-induced hearing loss (NIHL).The longer the sea service of sailors was and the longer they exposed to ship noise,the greater hearing damage they would sustain.For instance,the rate of hearing loss for sailors with 31 years of sea service or longer would reach as high as 35.2％.Statistical differences could be seen in the severeness of hearing damage among different groups of sailor with different length of sea service (P ＜ 0.01).There was statistical significance in the rate of hearing loss,when comparisons were made between the engine department sailors (21.1％) and the deck department sailors (11.4％) (P ＜ 0.01).The rate of hearing loss for the sailors wearing ear plugs frequently was much lower than those not wearing them,also with statistical significance (P ＜ 0.01).Conclusions Due to the high rate of hearing loss among sailors,the application of ear plugs could alleviate noise-induced hearing loss to some extent.It is of practical importance to develop and adopt highly effective,convenient and nontoxic intervention measures or devices against noiseinduced hearing loss.