The working principle and composition of a sound level meter
The inherent irregular motion and mutual repulsion of air molecules form a static force, which is atmospheric pressure. Sound is the vibration of air molecules, and the vibrating air molecules generate additional pressure on the cross-section they pass through, which is called sound pressure. The sound pressure is much smaller than atmospheric pressure, and the sound pressure level is generally used to describe the size of sound, that is, a very small sound pressure p0=2 х The sound pressure level is obtained by multiplying the ratio of the measured sound pressure p to the reference sound pressure p0 by the commonly used logarithm of 10 to 5 Pa as the reference sound pressure, and the unit is decibels (db). The decibel (dB) is named after American telephone inventor Bell because the unit of decibel is too large, so it is used to represent 1/10 of a decibel. The operation in decibels is not linearly proportional, but logarithmically proportional. When using decibels to describe sound, the frequency needs to be given simultaneously.
The working principle and composition of a sound level meter
A sound level meter is a basic instrument in noise measurement, generally composed of a microphone, preamplifier, attenuator, amplifier, frequency weighting network, and effective value indicator head.
The working principle of a sound level meter is:
The microphone converts sound into electrical signals, and then the preamplifier transforms impedance to match the microphone with the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting (or external filter) on the signal, and then amplifies the signal to a certain amplitude through an attenuator and amplifier, and sends it to the effective value detector (or external level recorder). The noise level value is given on the indicator head.
