The working principle of sound level meter and its components
The inherent irregular motion and mutual repulsion of air molecules creates a static force, and this pressure is the atmospheric pressure. Sound is the vibration of air molecules, vibration of air molecules on the cross-section through which it will produce additional pressure, this additional pressure is called sound pressure. Sound pressure than the atmospheric pressure is much smaller than the general use of sound pressure level to describe the size of the sound, that is, a very small sound pressure p0 = 2 х10-5 Pa as a reference sound pressure, the measurement of the sound pressure p and reference sound pressure p0 ratio to take the common logarithm of the value obtained by multiplying by 20 is known as the sound pressure level, the unit is the decibel (db ). The decibel (dB) is named after the American telephone inventor Bell, because the unit of shell is too large, so the decibel is used, representing 1/10 of a shell. The operation of the decibel is not linearly proportional, but logarithmically proportional, the use of decibels to describe the sound needs to be given at the same time the frequency.
How a sound level meter works and what it consists of
A sound level meter is a *basic* instrument for noise measurement, generally consisting of a microphone, preamplifier, attenuator, amplifier, frequency weighting network, and RMS indicating meter head.
The working principle of sound level meter is:
The microphone converts the sound into an electrical signal, and then the preamplifier transforms the impedance so that the microphone matches the attenuator. The amplifier will add the output signal to the weighting network, frequency weighting of the signal (or external filter), and then through the attenuator and amplifier to amplify the signal to a certain amplitude, sent to the RMS detector (or external level recorder), in the indication of the meter head to give the numerical value of the noise sound level.
Sound Level Meter Maintenance
(1) Keep the exterior of the instrument clean;
(2) The microphone should be kept dry when not in use;
(3) The microphone diaphragm should be kept clean and should not be touched by hand;
(4) When the instrument is not used for a long time, it should be energized for 2h per month, and it should be energized for 2h per week during the mildew and rainy season.
(5) Instruments should be used in a timely manner to remove the battery when finished
(6) Regularly sent to the measurement department for calibration.
