The sound pressure level measured by a sound level meter through a frequency weighting network is called sound level. Depending on the weighting network used, it is referred to as A sound level, B sound level, and C sound level, with units denoted as dB (A), dB (B), and dB (C).

The sound level meter used for measuring noise can be divided into four types of response based on sensitivity:

1. Slow ": The time constant of the header is 1000ms, usually 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 transportation noise with large fluctuations. Fast gear approaches the human ear's response to sound.

3. Pulse or pulse hold ": The rising time of the needle is 35ms, used to measure pulse noise with a longer duration, such as punch presses, hammers, etc. The measured value is the large effective value.

4. Peak holding ": The rise time of the gauge needle is less than 20ms. It is used to measure pulse sounds with short duration, such as gun, cannon, and explosion sounds, and the measured value is the peak value, that is, the large value.

Sound level meters can be equipped with external filters and recorders to perform spectral analysis on noise. The domestically produced ND2 precision sound level meter is equipped with an octave band filter, which is easy to carry to the site and perform spectral analysis. Sound level meters can be divided into precision sound level meters and ordinary sound level meters based on their accuracy. The measurement error of a precision sound level meter is about 1dB, while that of a regular sound level meter is about 3dB.

Sound level meters can be divided into two categories according to their purposes: one is used to measure steady-state noise, and the other is used to measure non-stationary noise and impulse noise.

Integral sound level meter is used to measure the equivalent sound level of unstable noise over a period of time. A noise dosimeter is also an integral sound level meter, mainly used to measure noise exposure. Pulse type sound level meter is used to measure pulse noise, which conforms to the response of the human ear to pulse sound and the average time of the human ear's response to pulse sound.