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China Occupational Medicine ; (6): 319-323, 2020.
Article in Chinese | WPRIM | ID: wpr-881903


OBJECTIVE: To evaluate the application value of 40 Hz auditory event related potential(40 Hz AERP) in hearing assessment in workers exposed to noise by observing the consistency between pure tone audiometry(PTA) and 40 Hz AERP. METHODS: A total of 240 ears of 120 workers who exposed to noise with PTA high-frequency hearing threshold > 25 dB were selected as the research subjects using the convenient sampling method. The thresholds of PTA and 40 Hz AERP at different frequencies were investigated. According to the average hearing threshold of PTA language frequency, the workers were divided into normal hearing group and mild-, medium-, medium-severe-, severe-hearing loss groups, and the difference and correlation between the thresholds of 40 Hz auditory potential and PTA were analyzed. RESULTS: The response thresholds of 40 Hz AERP of 0.5, 1.0, 2.0 kHz in ears of normal hearing group, and mild-and moderate-hearing loss groups were higher than the PTA hearing threshold(P<0.01), while the 40 Hz AERP response thresholds of 0.5 kHz in the ears of medium-severe-and severe-hearing loss groups were lower than the hearing thresholds of PTA(P<0.05). The different value of the response threshold of 40 Hz AERP and PTA of 1.0 and 2.0 kHz in ears of normal hearing group was higher than 0.5 kHz(median: 25.0 vs 15.0 dBHL, 30.0 vs 15.0 dBHL, P<0.01). Except for 0.5 and 1.0 kHz of mild-hearing loss group, the different value of the response threshold of 40 Hz AERP and PTA in ears of the other hearing loss groups were lower than that of the normal hearing group(P<0.01). The 40 Hz AERP response threshold was frequency-specific and correlated well with PTA at the same frequency. The correlation coefficients of 0.5, 1.0 and 2.0 kHz were 0.744, 0.732 and 0.665 respectively(P<0.01). CONCLUSION: It is feasible to evaluate PTA in noise-exposed workers using 40 Hz AERP response threshold, but the 40 Hz AERP cannot completely replace PTA. The measurement frequency and the degree of hearing loss should be considered simultaneously.

Article in Chinese | WPRIM | ID: wpr-441825


Objective To study the changes of hearing function and cochlear morphology on diffuse brain in-jury model in rat .Methods One hundred and fifty SD rats with normal hearing were randomly divided into five groups ,each group consisted of 30 SD rats ,including a control group and four experimental groups which endured diffuse brain injury(DBI) from one to four weeks .Diffuse brain injury model of rats were established ,then ABR , 40 Hz AERP and ASSR examination ,light microscopy ,electron microscopy were used to evaluate the change of hearing function and morphology .Results The difference of ABR ,40 Hz AERP and ASSR thresholds between the experimental and the normal control group were significant (P<0 .05) .The thresholds of ABR ,40HzAERP and AS-SR were increased in the first week of DBI ,then the threshold continuously increased in the second and third week , at last the threshold decreased in the fourth week .The results under scaning electron microscope demonstrated that the ciliums of the majority of outer hair cells lodged in the first week of DBI .The results under transmission electron microscope showed that in the first week of DBI ,there were edema and denuration of mitochondrial ,mitochondrial cristaes were obscured or disappeared .The changes were deteriorate in the second and third week ,whereas the changes were mitigatal in the fourth week .Conclusion Cochlear morphology and hearing damage were observed in diffuse brain injury model of rats .