Why do you need to calibrate a sound level meter before use?
Sound level meter is a basic noise measurement instrument, which is a subjective electronic instrument, different from objective electronic instruments such as voltmeter. It can convert sound signals into electrical signals and simulate the time characteristics of the human ear's response speed to sound waves; The frequency characteristics with different sensitivities to high and low frequencies, as well as the intensity characteristics that change the frequency characteristics at different loudness levels.
The working principle is that the sound is converted into an electrical signal by the microphone, and then the impedance is transformed by the preamplifier to match the microphone with the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting on the signal (or an external filter), and then amplifies the signal to a certain amplitude through an attenuator and amplifier, and sends it to the effective value detector (or an external level recorder). The noise level value is displayed on the indicator head. However, the principles of different types of sound level meters may also have some differences.
According to the sensitivity of the whole sound level meter, there are two methods for classifying sound level meters: one is ordinary sound level meters, which do not require high requirements for the microphone. The dynamic range and frequency response flat range are relatively narrow, and generally do not configure bandpass filters for use in conjunction; Another type is precision sound level meters, whose microphones require wide frequency response, high sensitivity, good long-term stability, and can be used in conjunction with various bandpass filters. The amplifier output can be directly connected to level recorders and recorders to display or store noise signals. If the microphone of a precision sound level meter is removed and replaced with an input converter and connected to an accelerometer, it becomes a vibration meter that can be used 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 and obtain a value. The range of values should be 94.0dB plus or minus 0.5dB. If it exceeds this range, the measurement behavior will be invalid.
