The Principle and Introduction of the Decibel Meter Noise Meter Sound Level Meter
Noise Meter Head Response Indicators
At present, noise meters for measuring noise, meter head response can be categorized into four types according to sensitivity:
(1) "Slow". The meter head has a time constant of 1000 ms and is generally used to measure steady state noise, with the measured value being the RMS value.
(2) "Fast". The time constant of the meter head is 125 ms, and it is generally used for measuring large fluctuation of unsteady noise and transportation noise, etc. The fast gear is close to the human ear's perception of sound. The fast gear is close to the human ear's response to sound.
(3) "Pulse or pulse hold". The rise time of the meter needle is 35ms, used to measure the impulse noise with longer duration, such as punch, press hammer, etc. The measured value is the *larger RMS value.
(4) "Peak hold". The rise time of the meter needle is less than 20ms. It is used to measure the impulse sound with short duration, such as gun, cannon and explosion sound, and the measured value is the peak value. That is, the * big value.
Classification:
Noise meters can be divided into precision noise meters and ordinary noise meters according to accuracy. Precision noise meter measurement error of about earth 1dB, ordinary noise meter about earth 3dB. noise meter according to the use can be divided into two categories: a class used to measure the steady state noise, a class is used to measure the unsteady state noise and impulse noise.
Integral noise meter is used to measure the equivalent sound level of unsteady noise over a period of time. A noise dosimeter is also an integrating noise meter and is primarily used to measure noise exposure.
Impulse noise meters are used to measure impulse noise, and this type of noise meter matches the response of the human ear to impulse sound and the averaging time of the human ear's response to impulse sound.
Principle of operation:
A noise meter is the most basic instrument in noise measurement. Noise meters are generally composed of a condenser microphone, a preamplifier, an attenuator, an amplifier, a frequency weighting network, and an RMS indicator head. The working principle of the noise meter is: the microphone converts the sound into an electrical signal, and then the preamplifier transforms the impedance to match the microphone with the attenuator. Amplifier will be added to the output signal weighting network, the signal frequency weighting (or external filter), and then by the attenuator and amplifier will be amplified to a certain amplitude of the signal, sent to the RMS oscilloscope (or outside the level recorder), in the indication of the meter head to give the numerical value of the noise level.
