What gives a different level or importance to each frequency and is applied by the sound level meter according to the settings chosen?

The weighting network is a crucial component in sound level meters that assigns different levels of importance to various frequencies. This process is essential because human hearing does not respond equally to all frequencies; certain frequencies are perceived more acutely than others. The weighting networks, such as A-weighting, C-weighting, and others, adjust the measured sound levels accordingly to reflect a more accurate representation of how sound is experienced by the human ear.

When a sound level meter is set to a particular weighting, it applies a filter that either emphasizes or attenuates certain frequencies. For instance, A-weighting is designed to mimic the sensitivity of human hearing at lower sound levels, thus giving a different reading for higher frequencies compared to lower ones. This adjustment is vital for accurate sound level measurement in both occupational health and environmental noise assessments.

While the sound intensity level refers to the power of sound waves, it does not account for human perception and is not influenced by settings on the sound level meter. The frequency response curve illustrates how a system responds across different frequencies but does not actively apply a weighting to the sound levels. The decibel scale is simply a unit of measurement for sound intensity and does not differentiate levels according to frequency importance. Thus, the weighting network is the mechanism that