Basic knowledge of sound level meter and how to choose the right type
Measuring range
The measurement range of the sound level meter is the main technical index of the sound level meter. This technical index represents the technical advancement of the product to some extent. Generally, 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 a high sound pressure level (for example, 172 dB) needs to be measured, a high sound pressure microphone must be selected. The measurement lower limit of the sound level meter has a lot to do with the self-generated noise of the sound level meter itself. If you want to measure low sound level noise, you should choose a sound level meter equipped with a high-sensitivity microphone.
interface
The current sound level meter generally has RS232, USB and other interfaces for connecting to a micro-printer or computer, and the user can choose according to the test needs. There are also some sound level meters with wireless transmission function. If the tester needs to have a certain distance from the environment under test during measurement, then it is most suitable to choose a sound level meter with wireless function.
Certificate
my country's State Administration for Market Regulation issued an announcement (No. 48, 2019) on the catalog of measuring instruments for compulsory management last year, including the sound level meter used for environmental monitoring in the catalog of measuring instruments for compulsory management, implementing the P+V supervision method, requiring ( New product) for type approval (P), and compulsory verification (V) should be accepted during use.
Users who choose a sound level meter must know in advance whether the manufacturer has obtained the type approval certificate (CPA) of the sound level meter. The sound level meter in use by the user can only be used normally if the verification certificate is issued by the metrology department and the qualified conclusion and accuracy level are drawn and within the validity period (one year). If only a calibration certificate or test report is issued, it cannot prove that the sound level meter The performance meets the requirements of GB/T 3785.1-2010 (IEC 61672-1:2013). The "Announcement" also stipulates that those who have not obtained the type approval certificate after November 1, 2020, shall be ordered to stop manufacturing, selling and importing, and be punished in accordance with relevant regulations.
For sound level meters for other purposes, the type evaluation test shall also be carried out according to GB/T 3785.2 "Electroacoustic Sound Level Meter Part 2: Type Evaluation Test" according to the requirements of national standards, and the type evaluation certificate shall be obtained and publicized, otherwise due to periodic The scope of the test is limited, even if the results of the periodic test meet all the relevant requirements of GB/T 3785.3, it cannot be concluded that it meets the performance requirements of the sound level meter.
Supporting calibrator
The sound level meter needs to use a sound calibrator for sound calibration during use. The sound calibrator is often used as a supporting instrument for the sound level meter and becomes an integral part of the sound level meter. The sound calibrator shall meet the requirements of GB/T 15173 for a Class 1 or Class 2 sound calibrator, a Class 1 sound level meter shall be calibrated with a Class 1 sound calibrator, and a Class 2 sound level meter shall be calibrated with a Class 2 or Class 1 sound calibrator calibration. It should be noted that some acoustic calibrators are greatly affected by altitude (mainly due to the influence of atmospheric density), and need to be corrected, or an acoustic calibrator with less air pressure influence should be selected to avoid affecting the measurement accuracy.
