Introduction to Several Typical Sound Level Meters
1. Integral sound level meter - capable of directly displaying the equivalent continuous sound level of the measured noise within a certain measurement time in digital form. For non-stationary noise, it is required to measure the equivalent continuous sound level Leq of the noise, which is defined as: at a certain point in the sound field, using the method of averaging energy over a certain period of time, intermittently changing several different A sound levels are represented as one A sound level to represent the magnitude of the noise during that period.
2. Digital sound level meter - a sound level meter that displays measurement results digitally. It not only has the advantages of intuitive and accurate readings, but also can be processed in conjunction with other analytical and processing instruments and computers through BCD code output.
3. Pulse sound level meter - measures the effective value of the measured signal through the pulsation characteristics of the capacitor at different times, and has a high peak factor capacity, so it can respond to pulse sound with short duration and low repetition ratio. In daily life, we often encounter discontinuous noise, namely pulse or impact sound, such as typewriter noise, stamping machine noise, guns, and so on. This type of noise has a short duration and may recur for a long time, even appearing only once over a period of time. Measuring with a general sound level meter can result in significant errors, so a pulse sound level meter should be used.
4. Environmental automatic monitoring (noise statistics, spectrum) analyzer - capable of automatically collecting and calculating noise data according to pre-set functions, and displaying the results directly (while storing data)
Why do I need to calibrate a sound level meter before using it
1. Sound level meter measurement is the process of converting the vibration wave signal of the metal diaphragm of the microphone (microphone head) in the front end of the sound level meter into an electrical signal caused by the vibration wave of air vibration caused by the sound signal (sound wave). After being amplified by a dedicated weighing network and circuit operation, the noise decibel value is displayed by digital or electric meter.
2. The quality of air is unstable, such as temperature, humidity, atmospheric pressure, etc., which can change at any time due to environmental and other factors. To ensure the accuracy of the air vibration signal received by the metal diaphragm of the microphone, the sensitivity of the microphone needs to be adjusted accordingly.
3. The process of adjusting the sensitivity of a microphone is to calibrate the sound level meter.
4. The national standard stipulates that "measuring instruments must be calibrated with a sound level calibrator before and after measurement, and the deviation of the calibrated instrument's indication must not exceed 0.5dB, otherwise the test will be invalid.
