In noise control engineering, in order to make the objective physical quantity of sound consistent with the auditory characteristics of the human ear, people set up three frequency weighting networks in the sound level meter: A, C and Z frequency weighting.
Since the human ear has different perception capabilities for noise in each frequency band, it is most sensitive to the intermediate frequency around 500Hz to 6kHz, and is less sensitive to low frequency and high frequency. In order to simulate the different sensitivities of human hearing at different frequencies, there is a network in the sound level meter that can simulate the auditory characteristics of the human ear and correct the electrical signal to an approximate value of hearing. This network is called frequency weighting. , which are essentially some filters.
In the measurement process, to correctly select the required frequency weighting, when the measurement is over, it is impossible to convert the measurement data from one frequency weighting to another frequency weighting. That's why to use Cirrus Optimus series sound level meters, Optimus series sound level meters can measure and record all frequency weighted data in the same measurement process, avoiding measurement parameter errors or repeated measurement, saving you time.
A-weighted
A-weighting simulates the response of the human ear to sound, so that the middle and low frequency bands of the electrical signal have a greater attenuation. The A-weighted filter covers the frequency range from 20Hz to 20KHz. Measurements that use A-weighting are usually labeled dB(A), such as LAeq, LAFmax, LAE, etc., where A indicates that A-weighting is used.
C weighting
The C-weighted sound level is a frequency characteristic that simulates high-intensity noise. Measurements that use C-weighting are usually labeled dB©, such as LCeq, LCPeak, LCE, etc., where C indicates that C-weighting is used.
Z weighting
Z-weighting is the horizontal response to the frequency range 20Hz to 20KHz, ±1.5dB, excluding the microphone response. Measurements that use Z-weighting are usually labeled dB(Z), such as LZeq, LZFmax, LZE, etc., where C indicates that C-weighting is used.
