GBZ/T 189.8-2007Measurement of physical agents in workplace - Part 8: Noise (English PDF)

2.1 Sound level meter: Type 2 or above, with A-weighting, "S (slow)" gear.

2.2 Integrating sound level meter or personal noise dosimeter: Type 2 or above, with A-

weighting, C-weighting, "S (slow)" gear and "Peak (peak)" gear.

3.1 On-site investigation

In order to correctly select the measurement point, measurement method, measurement

time, etc., it is necessary to conduct an on-site investigation of the workplace, before

the measurement. The investigation contents mainly include:

3.1.1 Draw a sketch for the area, space, process division, noise equipment layout, etc.

of the workplace.

3.1.2 Division of work flow, noise characteristics of each production procedure, noise

change law, etc.

3.1.3 Pre-measurement, to determine whether the noise is stable and whether the

distribution is uniform.

3.1.4 Number of staff, working routes, working methods, stay time, etc.

3.2 Preparation of measuring instruments

3.2.1 Selection of measuring instruments: Sound level meters are used for fixed job

positions; individual noise dosimeters are preferred for mobile jobs, OR sound level

meters are used for different workplaces, to measure separately and calculate the

equivalent sound level.

3.2.2 The measuring instrument shall be calibrated, according to the instrument

calibration requirements, before measurement.

3.2.3 Integral sound level meter or personal noise dosimeter is set to A-weighting, "S

(slow)" gear; the value is sound level LpA or equivalent sound level LAeq. When

measuring impulse noise, use "Peak (peak value)" gear.

3.3 Measuring point selection

3.3.1 When the sound field in the workplace is evenly distributed [A sound level

difference within the measurement range is less than 3 dB(A)], select 3 measuring

points; take the average value.

3.3.2 When the sound field distribution in the workplace is uneven, it shall be divided

into several sound level areas; the sound level difference within the same sound level

area is < 3 dB(A). In each area, select 2 measuring points; take the average value.

3.3.3 Workers are mobile. Within the mobile range, make measurements at the

workplaces respectively; calculate the equivalent sound level.

3.3.4 Refer to Appendix A, for the sampling method using personal noise dosimeters.

3.4 Measurement

3.4.1 The microphone shall be placed at the height of the ears of the workers, when they

are working, 1.50 m for standing gesture and 1.10 m for sitting gesture.

3.4.2 The direction of the microphone is pointing to the sound source.

3.4.3 The measuring instrument is fixed on a tripod and placed at the measuring point;

if the tripod is not suitable for placement on site, the sound level meter can be held by

hand; however, the distance between the tester and the microphone shall be kept > 0.5

m.

3.4.4 For workplaces with steady-state noise, make 3 measurements at each measuring

point; take the average value.

3.4.5 For workplaces with unsteady noise, determine the time period, according to the

sound level change (sound level fluctuation >= 3 dB); measure the equivalent sound level

of each time period; record the duration of each time period.

3.4.6 When measuring impulse noise, it shall measure the peak value of impulse noise

and the number of impulses in a working day.

3.4.7 Measurements shall be carried out under normal production conditions. When the

wind speed in the workplace exceeds 3 m/s, the microphone shall wear a windshield.

Electromagnetic field interference shall be avoided, as much as possible.

Where:

LEX,W - Refers to the average weekly exposure value (A-weighted), in decibels (dB);

LEX,8h - The equivalent sound level (A-weighted) of exposure noise intensity, which

is normalized to 8 hours of work during the actual working time of a day, in decibels

(dB);

n - Refers to the actual number of working days per week, in days (d).

3.5.4 Impulse noise: Using the integral sound level meter, "Peak (peak value)" gear, it

can directly read the peak value of the sound level Lpeak.