Measuring range of sound level meter
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, 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 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, choose a sound level meter equipped with a high-sensitivity microphone.
Accuracy class of sound level meter
According to different accuracy levels, sound level meters are divided into level 1 accuracy and level 2 accuracy. The difference between level 1 and level 2 is mainly in the maximum allowable error, operating temperature range and frequency range, and the accuracy of level 1 sound level meter is higher than that of level 2. Although in general, the use of a Class 2 sound level meter can meet the measurement requirements, but more and more Class 1 sound level meters are used. According to my country's environmental noise regulations, when the noise A sound level is lower than 35 dB, it is required to use A sound level meter that meets Class 1 accuracy.
Time Weighting of Sound Level Meter
In real life, there are many types of noise, including steady-state noise, transient noise, and impulse noise, etc., and time weighting is introduced for different noise measurements. Time weighting is actually the time averaging of the measurement signal. Usually, the time averaging feature includes four modes, namely "Fast" (Fast) file, "Slow" (Slow) file, "Impulse" (Impulse) file and "Peak Hold" (Peak) file.
For continuous sound signals, usually "fast" and "slow" weights are used. The weighting time constant of the "fast" gear is 125ms, which is generally used to measure unstable noise and traffic noise with large fluctuations. The fast gear is close to the human ear's response to sound. The weighting time constant of the "slow" gear is 1000ms, which is generally used to measure steady-state noise, and the measured value is an effective value. For steady-state continuous sound signals, there is no significant difference between the two weighting methods. However, if the measured sound fluctuates greatly, the result obtained by weighting with "slow gear" is more stable due to the different length of weighting time. However, due to the long averaging time, there will be errors in peak and valley measurements. Therefore, in order to accurately understand the real-time changes of the signal, it is advisable to use the "fast" gear weighting (the fast gear is close to the human ear's response to sound, and the fast gear and A weighting should be used when measuring the background noise of the soundproof room).
Time weighting is usually used in sound level meter measurement, and the time weighting is used in conjunction with the previous frequency weighting to make the measurement results reflect the subjective perception characteristics of the human ear to a certain extent. In addition, the sound level meter can be connected with an external filter and recorder to perform spectrum analysis on the noise.
