[Comparative investigation of hearing injury in workers exposed to punching machine noise and to steady state noise].
OBJECTIVE
To compare the difference of effects on hearing injury between punching machine noise and steady state noise.


METHODS
The subjects of present study were 100 workers, included 38 workers exposed to punching machine noise from forging shops and 62 workers exposed to steady state noise from drawbench or abrasive dust workshops. The individual noise dosimetries were used to detect noise that workers exposed, and cumulative noise exposure (CNE) was then calculated. On the basis of GBZ 49-2007, the worker hearing was tested, and the results were assessed.


RESULTS
There were no differences of CNE between group exposed to punching machine noise and group exposed to steady state noise. The hearing loss rate (55.3%) at high frequency in workers exposed to punching machine noise was significantly higher than that (32.3%) in workers exposed to steady state noise (P < 0.01). CNE and the hearing loss rate at high frequency showed dose-response relationship (P < 0.01).


CONCLUSIONS
when the exposure levels of workers were similar, the hearing injury induced by punching machine noise may be significantly higher than that induced by steady state noise.
Deqing County Center of Disease Control and Prevention, Deqing, Zhejiang Province, China.
Guo-ying
GY
Zhang
Zhi-feng
ZF
Tang
Yong-ping
YP
Yao
D000328:Adult; D006317:Hearing Loss, Noise-Induced; D006801:Humans; D008297:Male; D009623:Noise, Occupational / Q000009:adverse effects*; D016273:Occupational Exposure / Q000032:analysis*; D011795:Surveys and Questionnaires