Basic knowledge of sound level meters and how to choose the correct one?
Measuring range
The measurement range of the sound level meter is the main technical indicator of the sound level meter. This technical indicator represents the technological advancement of the product to a certain extent. Generally, it is hoped that the wider the measurement range, the better. The measurement upper limit of the sound level meter is determined by the maximum undistorted sound level of the sound level meter, which can generally reach 130 dB. If you need to measure a high sound pressure level (for example, 172 dB), you need to use a high sound pressure microphone. The lower measurement limit of a sound level meter is closely related to the self-generated noise of the sound level meter itself. If you are measuring low-level noise, choose a sound level meter equipped with a high-sensitivity microphone.
interface
Current sound level meters generally include RS232, USB and other interfaces for connecting to micro printers or computers. Users can choose according to testing needs. Some sound level meters also have wireless transmission capabilities. If the tester needs to be at a certain distance from the environment being measured during measurement, then it is most appropriate to choose a sound level meter with wireless capabilities.
Certificate
Last year, my country's State Administration for Market Regulation issued an announcement (No. 48, 2019) on the implementation of the catalog of compulsorily managed measuring instruments. The sound level meter used for environmental monitoring was included in the catalog of compulsorily managed measuring instruments, and the P+V supervision method was implemented, requiring ( New products) must apply for type approval (P), and must undergo mandatory verification (V) during use.
When users choose a sound level meter, they must check in advance whether the manufacturer has obtained the Type Approval Certificate (CPA) for the sound level meter. The sound level meter in use by the user can only be used normally if the measurement department issues a calibration certificate and reaches a qualified conclusion and accuracy level and within the validity period (one year). If only a calibration certificate or test report is issued, the sound level meter cannot be certified. The performance is in compliance with the requirements of GB/T 3785.1-2010 (IEC 61672-1:2013). The "Announcement" also stipulates that those who fail to obtain a type approval certificate after November 1, 2020 will be ordered to stop manufacturing, sales and imports, and will be punished in accordance with relevant regulations.
For sound level meters for other purposes, according to national standards, type evaluation tests should also be carried out in accordance with GB/T 3785.2 "Electroacoustic Sound Level Meters Part 2: Type Evaluation Test", and a type evaluation certificate should be obtained and made public. Otherwise, due to periodic The scope of the test is limited. Even if the results of the periodic test meet all relevant requirements of GB/T 3785.3, it cannot be concluded that the performance requirements of the sound level meter are met.
