Calibration method of sound level meter_Why do you need to calibrate the sound level meter before using it?
The sound level meter is a basic noise measuring instrument, which is a subjective electronic instrument, which is different from objective electronic instruments such as voltmeters. It can convert the acoustic signal into an electrical signal, which can simulate the time characteristics of the human ear's response speed to sound waves; the frequency characteristics of different sensitivities to high and low frequencies, and the intensity characteristics of changing the frequency characteristics at different loudness.
Its working principle is that the microphone converts the sound into an electrical signal, and then the preamplifier transforms the impedance to match the microphone with the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting on the signal (or external filter), and then amplifies the signal to a certain amplitude through the attenuator and amplifier, and sends it to the effective value detector (or external press circuit Level recorder), the numerical value of noise sound level is given on the indicator head. However, the principles of different types of sound level meters will also be somewhat different.
According to the sensitivity of the sound level meter, there are two types of sound level meter classification: one is the ordinary sound level meter, which does not require too much microphone. The dynamic range and flat frequency response range are relatively narrow, and generally not equipped with a band-pass filter; the other is a precision sound level meter, whose microphone requires wide frequency response, high sensitivity, good long-term stability, and can Used in conjunction with a band-pass filter, the output of the amplifier can be directly connected to a level recorder or a tape recorder, and the noise signal can be displayed or stored. If the microphone of the precision sound level meter is removed and replaced with an input converter and connected to an accelerometer, it becomes a vibration meter for vibration measurement.
Moreover, there are certain differences in the measurement methods of different sound level meters, but the same is the calibration method of the sound level meter, which is to put the calibrator on the sound level meter before measurement to obtain a value. The range of the value should be 94.0dB plus or minus 0.5dB, beyond this range, the measurement will be invalid.
