What is a sound level meter
Sound level meter is the basic instrument for acoustic (noise) measurement, it measures the sound pressure level or sound level of sound according to certain frequency weighting and time weighting.
Composition of sound level meter: Sound level meter is the most basic instrument in noise measurement, generally composed of condenser microphone, preamplifier, attenuator, amplifier, frequency weighting network and RMS indicator.
The working principle of the sound level meter is: the sound is converted into an electrical signal by the microphone, and then the impedance is transformed by the preamplifier to match the microphone and the attenuator. The amplifier adds the output signal to the weighting network, performs frequency weighting on the signal (or external filter), and then amplifies the signal to a certain amplitude through the attenuator and amplifier, and sends it to the RMS detector (or external power supply). flat recorder), the numerical value of the noise sound level is given on the indicator head.
At present, the sound level meter used to measure noise, the meter response can be divided into four types according to the sensitivity:
(1) "Slow". The time constant of the meter head is 1000 ms, which is generally used to measure steady-state noise.
The resulting value is a valid 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 maximum effective value.
(4) "Peak Hold". The rising time of the needle is less than 20ms. Used to measure pulsed sounds of short duration.
The sound level meter can be connected to an external filter and recorder to perform spectrum analysis on noise.
Sound level meters can be divided into precision sound level meters and ordinary sound level meters according to their accuracy. The measurement error of a precision sound level meter is about ±1dB, and that of an ordinary sound level meter is about ±3dB. Sound level meters can be divided into two categories according to their use: one is used to measure steady-state noise, and the other is used to measure unsteady noise and impulse noise.
The integrating sound level meter is used to measure the equivalent sound level of unsteady noise over a period of time. A noise dosimeter is also an integrating sound level meter, mainly used to measure noise exposure.
Impulse sound level meter is used to measure impulse noise, this kind of sound level meter accords with human ear's response to impulse sound and the average time of human ear's response to impulse sound.
