Objective To measure and evaluate the eight-hour continuous equivalent A-weighted sound levels (LAeq.8 h), one-minute continuous equivalent A-weighted sound levels (LAeq.1 min), and continuous equivalent A-weighted sound levels over a work day (LAeq.T) of non-steady noise at work.
Methods LAeq.8 h was determined by personal noise dosimeter. LAeq.1 min was measured by environmental noise dosimeter. LAeq.T was calculated with LAeq.1 min. A Total of 239 workers exposed to non-steady noise in a pipeline manufacturing factory and a household appliance factory were investigated using LAeq.8 h. Workplace noise levels were measured using LAeq.1 min and LAeq.T.
Results The averages of LAeq.8 h in the two factories(89.7& #177;3.8) dB(A) and (90.5& #177;5.7) dB(A) were significantly higher than the averages of LAeq.T(88.0& #177;2.4) dB(A) and (89.2& #177;3.6) dB(A) (P< 0.05 or P< 0.01). Sampling time errors of the values of LAeq.1 min were observed as compared with the values of LAeq.8 h. The differences between the mean values of LAeq.1 min and LAeq.8 h at most of the work locations were greater than 3 dB(A). The differences between the mean values of LAeq.T and LAeq.8 h at all work locations were less than 3.0 dB(A).
Conclusion LAeq.8 h is able to measure the non-steady noise level of workers. LAeq.T reflects actual noise levels of workers. LAeq.1 min may underestimate or overestimate noise levels.
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