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目的探讨噪声测量时点数量与工作日噪声暴露(LAeq. 8 h)评估准确性的关系。方法采用SH126型记录式声级计,在某纺织厂测量59个8 h工作班次的噪声水平,其中挡车班次25个、机修班次34个。对每一班次的测量均按10 min间隔顺序记录48个10 min等效连续A声级(LAeq.10 min)。为模拟日常工作中根据特定时点短时噪声测量结果估算LAeq.8 h的方法,应用区组随机抽样程序进行8轮抽样,分别从59组数据中抽取1、2、3、4、5、6、7、8个LAeq.10 min,根据抽样结果估算8个LAeq. 8 h。用估算LAeq.8 h与真实LAeq.8 h(根据全部48个LAeq.10 min计算得出)之差的绝对值反映LAeq.8 h估算误差,评价增加测量时点对LAeq估算误差的影响。结果挡车工、机修工噪声暴露方式明显不同,前者为典型稳态噪声暴露,而后者表现为非稳态噪声暴露。当测量时点为1时,挡车工暴露估算误差为(1.00±1.33)dB,而机修工为(8.62±11.90)dB。两类暴露LAeq.8 h估算误差均随测量时点增加而下降,在测量时点数达3~4个时,下降曲线逐渐平坦。测量时点数目相等时,机修工暴露估算误差均大于挡车工。结论按单一时点的测量结果估算非稳态噪声LAeq.8 h可能会导致较大误差,增加测量时点可减少估算误差。就稳态噪声暴露而言,增加测量时点去除LAeq.8 h估算误差的意义较小。
Objective To explore the relationship between the number of noise measurements and the assessment accuracy of working day noise exposure (LAeq. 8 h). Methods Using SH126 recording sound level meter, the noise level of 59 8 h work shifts in a textile factory was measured, including 25 shift shifts and 34 shift trips. For each shift, 48 10-minute equivalent continuous A-sound levels (LAeq. 10 min) were recorded in 10-min intervals. In order to simulate the method of estimating LAeq.8h according to the noise measurement results of short-time at a specific point in daily work, eight random sampling procedures were used to sample eight samples from 59 groups, 6, 7, 8 LAeq. 10 min, 8 LAeq. 8 h were estimated based on the sampling results. The absolute value of the difference between LAeq.8h and true LAeq.8h (calculated from all 48 LAeqs.10mins) reflects the LAeq.8h estimation error and evaluates the effect of increasing measurement time on the LAeq estimation error. As a result, there was a significant difference in noise exposure between mechanics and mechanics. The former was a typical steady-state noise exposure and the latter was unsteady noise exposure. When the measuring point is 1, the estimated error of driver’s exposure is (1.00 ± 1.33) dB, while the mechanic is (8.62 ± 11.90) dB. The error of estimation of two kinds of exposed LAeq.8h decreased with the increase of measurement time point. When the number of points was up to 3 ~ 4, the decline curve became flat. When the number of measurement points is equal, the estimated error of mechanic exposure is greater than that of the driver. Conclusion The estimation of unsteady noise LAeq by a single point measurement may lead to large errors. Increasing the measurement time may reduce the estimation error. For steady-state noise exposure, it is less meaningful to increase the measurement error by 8 h when LAeq is removed.