Noise operation refers to the operation with sound harmful to hearing, health or other hazards, and the equivalent sound level of 8h/d or 40h/w noise exposure is ≥80dB(A). Noise can cause damage to many systems of human body, but the main characteristic damage is in auditory organs. Noise below 80dB(A) will not cause hearing loss after lifetime exposure. Below 85dB(A), it has no effect on 90% people; Below 90dB(A), it has no effect on 85% people. In the production environment, because the positions of noise sources and workers often change, the noise emitted by noise sources changes with time, resulting in unstable data and great differences. Taking a metal processing enterprise as an example, this paper compares the advantages, disadvantages and applicable conditions of three noise testing methods for the same type of workers.

1 objects and methods

1. 1 object

A metal processing enterprise in Jiading District, Shanghai, the working system is eight hours a day, five days a week. Noise detection of 0/0 noise workers in some workshops/KLOC. The noise emitted by the noise source changes irregularly with time, and the equipment is turned on for less than 8 hours, which belongs to unsteady noise.

1.2 method

1.2. 1 instrument

(1)AWA 56 10 B personal sound exposure meter.

(model hs6288b noise spectrum analyzer.

1.2.2 noise detection

The detection method is based on Measurement of Physical Factors in Workplace Part 8: Noise (GBZ/T 189.8-2007). On the same working day and in the same post, three methods are used for detection: individual noise dosimeter measurement, multi-cycle measurement by comprehensive sound level meter and single-cycle measurement by comprehensive sound level meter. Personal noise dosimeter measurement is detected by personal sound exposure meter, and multi-period measurement of comprehensive sound level meter and single-period measurement of comprehensive sound level meter are detected by noise spectrum analyzer.

Personal noise dosimeter measurement method: personal sound exposure meter, the test microphone is fixed at the collar of the tested person, and the equivalent A sound level of this time period is read every 2 seconds. * * * Measure the whole working shift for 8 hours, save the data of 14400, and calculate the equivalent sound level of this position for 8 hours.

Multi-period measurement method of integrated sound level meter: according to the change of noise sound level, it is divided into multiple time periods, and the equivalent sound level in each time period is measured, and the equivalent sound level of 8 hours is calculated according to the duration of each time period.

Single-period measurement method of integrated sound level meter: according to the working characteristics of the machine, measure the equivalent sound level of noise in a period of time when the machine is working, which represents the equivalent sound level of the machine during the opening period; Measure the equivalent sound level of workers' contact noise when the machine is not turned on and the corresponding time period, and calculate the equivalent sound level of 8h according to the unsteady noise formula.

2 conclusion

The harm of occupational noise in China is very serious. According to statistics, the incidence of hearing loss is 20%~50% in different industries. At present, there are more than 6,543,800,000 employees working in an environment with excessive noise, and millions of them have hearing loss to varying degrees. First of all, we should do a good job in noise detection and put forward corresponding preventive measures. How to detect it is particularly important. In many workplaces, the noise forms are diverse and chaotic, so the individual noise dosimeter measurement method is the first choice, and the detection result is the closest to the true value. Disadvantages of personal sound exposure meter: the measurement time is long (one shift time), and every examinee needs to wear the instrument. When there are many detection positions, it takes a long time. The integrated sound level meter has high requirements for personnel, accurate division of noise periods and heavy workload in one day, and can replace personal sound level meters in places with complex noise. The single measurement method of integrated sound level meter has the advantages of short detection time and high measurement efficiency, but the disadvantage is that it is not suitable for the workplace with complex noise, otherwise the measurement result has a large deviation, and it is only suitable for the situation that the noise level changes slightly to steady state or periodically when the equipment works.

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