(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 maximum 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, and the measured value is the peak value. i.e. the maximum value. Range finder, altimeter, laser line cast meter, flow meter, GPS thickness gauge, level meter, flat meter, waveform recorder, test fixture, voltage and current recorder, data recorder, graphic recorder
