The structure of the noise analyzer and the principle of its operation
Noise analyzer, also known as noise meter (noise meter, sound level meter), is the most basic instrument in noise measurement. A sound level meter generally consists of a condenser microphone, preamplifier, noise meter image attenuator, amplifier, frequency meter network, and effective value indicator head.
The working principle of a sound level meter is that the sound is converted into an electrical signal by a microphone, and then the impedance is transformed by a preamplifier to match the microphone with an attenuator. The amplifier adds the output signal to the network, and then amplifies the signal to a certain amplitude through attenuators and amplifiers, and sends it to the effective value detector.
Introduction to Calibration and Measurement Methods of Sound Level Meters
Sensitivity calibration
To ensure measurement accuracy, calibration should be performed before and after use.
Connect the sound level calibrator to the microphone, turn on the calibration power, read the value, adjust the sensitivity potentiometer of the noise meter, and complete the calibration.
measuring method
When measuring, the instrument should choose the correct gear according to the situation, hold the noise meter on both sides with both hands, and point the microphone towards the measured sound source. Extension cables and extension rods can also be used to reduce the influence of the noise meter's appearance and human body on the measurement. The position of the microphone should be determined according to relevant regulations.
The classification of noise measurement mainly includes the following types:
1. From the perspective of measuring objects, it can be divided into the measurement of environmental noise (sound field) characteristics and the measurement of sound source characteristics.
2. According to the temporal characteristics of the sound source or field, it can be divided into steady-state noise measurement and non-stationary noise measurement. Unsteady noise can be divided into periodic variation noise, irregular variation noise, and pulse sound.
3. According to the frequency characteristics of the sound source or field, it can be divided into broadband noise, narrowband noise, and noise containing prominent pure tone components.
4. According to the required accuracy of measurement, it can be divided into precision measurement, engineering measurement, and noise survey.
