The Application of Sound Level Meter Weighting in Custom Frequencies
In addition to the A, C, and Z frequency weighting characteristics designed according to standards, the AWA6228 multifunctional sound level meter and AWA6291 real-time signal analyzer have added a custom frequency weighting function. Users can set frequency weighting factors at the center frequency points of each 1/3 octave band as needed. When performing real-time spectrum analysis of the 1/3 octave band, the instrument weights each measured sound pressure level in the 1/3 octave band according to the set custom frequency weighting factor, and then synthesizes it into a custom weighted sound level.
For example, in JGJ/T 170-2009 "Standard for Limits and Measurement Methods of Building Vibration and Secondary Radiation Noise Caused by Urban Rail Transit", it is required to measure indoor secondary radiation noise in the frequency range of 16 Hz~200 Hz. The custom frequency weighting function can be used. Under the custom frequency weighting menu, the weighting factor of each 1/3 octave band center frequency in the frequency range of 16 Hz~200 Hz can be set to the A weighting factor specified in the sound level meter standard (see table), and the weighting factor of other center frequency points can be set to - INF (i.e. - ∞).
The instrument will measure the custom weighted sound pressure level based on the custom weighting factor, while measuring other parameters, and represent it as W-U. Here, the sound pressure level value of indoor secondary radiation noise in the frequency range of 16 Hz~200 Hz is directly read out. The sound pressure level value can be either instantaneous, equivalent sound level, high sound level or low sound level.
