Noise meter is the most basic instrument in noise measurement. It is generally composed of condenser microphone, preamplifier, attenuator, amplifier, frequency weighting network and RMS indicator.
The sensitivity of the noise meter can be divided into four types:
(1) "Slow". The time constant of the meter head is 1000 ms, which is generally used to measure steady-state noise, and the measured value is the effective value.
(2) "Fast". The time constant of the meter head is 125ms, which is generally used to measure unstable noise and traffic noise with large fluctuations. Fast gear is close to the human ear's response to sound.
(3) "Pulse or pulse hold". The rise time of the needle is 35ms, which is used to measure pulse noise with a long duration, such as punches, hammers, etc. The measured value is the most effective value.
(4) "Peak Hold". The rise time of the needle is less than 20ms. It is used to measure pulse sounds with short duration, such as guns, guns and explosions. The measured value is the peak value. That is, the maximum value. The sound level meter can be connected to an external filter and recorder to perform spectrum analysis on noise. The domestic precision sound level meter is equipped with an octave page filter, which is easy to carry to the scene and for spectrum analysis.
