Noise test
Project Introduction
Noise pollution is one of the most influential environmental pollutions. High-decibel noise can even cause serious damage to people's eardrums, leading to deafness. The application of a noise tester can provide the decibels reached by the noise so that relevant measures can be taken to control and reduce the noise. The measurement unit of sound size is decibel. The professional noise tester used for noise testing has a highly sensitive sensor, high precision, and wide application range. It can be widely used for noise measurement in various environments.
Noise test standards
Noise detection is mainly based on the "Acoustic Environment Quality Standard 3096-2008" and "Environmental Noise Emission Standard for Industrial Enterprises at Factory Boundaries". The detection scope is: airport noise, factory boundary noise, regional noise, traffic noise, and sensitive point noise.

outdoor standards

Applicable areas for various standards:
Category 0 standards are suitable for areas that particularly require quietness, such as health care areas, high-end villa areas, and high-end hotel areas. Areas located in suburban areas and rural areas are subject to stricter standards of 5 decibels than Category 0.
Category 1 standards apply to areas dominated by residences and cultural and educational institutions. The rural living environment can refer to the implementation of such standards.
Category 2 standards apply to mixed residential, commercial, and industrial areas.
Category 3 standards apply to industrial areas.
Category 4 standards apply to areas on both sides of urban road traffic trunk roads and on both sides of inland waterways passing through urban areas. The background noise (referring to the noise level when no trains are passing through) limits on both sides of the main and secondary railway lines that pass through urban areas also comply with this type of standard.

2. Indoor standards:
Indoor noise standards can be divided into residential and non-residential. Residential indoor noise standards are formulated based on the requirements for quiet life and the environmental noise standards of the area, with reference to the conditions of residential windows. Generally, they should not be lower than 20 decibels below the environmental noise standards of the area.
China's residential indoor standards are set to be 10 decibels lower than the ambient noise standard in the area, because there are many small factories close to residences in Chinese cities. Non-residential indoor noise standards are specified based on the use of the room.
Test Methods
Environmental noise detection and measurement instruments are integrated average sound level meters or environmental noise automatic monitoring instruments with an accuracy of Type 2 or above. Their performance must comply with the regulations of GB3785 and GB/T 17181 and be calibrated regularly. Use an acoustic calibrator to calibrate the measuring instrument before and after measurement. The indication deviation shall not be greater than 0.5 dB, otherwise the measurement will be invalid. The acoustic calibrator shall meet the requirements of GB/T 15173 for Class 1 or Class 2 acoustic calibrators. The microphone should be equipped with a windshield during measurement.

According to the monitoring objects and purposes, the following three measuring point conditions (referring to the location of the microphone) can be selected to measure environmental noise:
1. General outdoor
Measured at least 3.5 m away from any reflecting object (except the ground) and at least 1.2 m above the ground. If necessary, it can be placed on a high-rise building to expand the monitoring sound range. When using a monitoring vehicle for measurement, the microphone should be fixed at a height of 1.2m on the top of the vehicle.
2. Outdoor noise-sensitive buildings
Outside noise-sensitive buildings, 1 m away from walls or windows and more than 1.2 m above the ground.
3. Indoors of noise-sensitive buildings
At least 1 m away from walls and other reflective surfaces, about 1.5 m away from windows, and 1.2 m to 1.5 m high from the ground.