Which three main weighting networks are commonly used in sound measurement?

The correct answer identifies the three main weighting networks commonly used in sound measurement, which are A, C, and Z.

The A-weighting network is designed to reflect the sensitivity of human hearing at different frequencies. It reduces the impact of very low and very high frequencies, focusing more on the mid-range frequencies where human hearing is most sensitive. This makes it particularly useful for measuring environmental noise and assessing potential hearing damage in occupational settings.

C-weighting is used for measuring sound levels in a more flat manner across all frequencies, with less emphasis on the lower frequencies compared to the A-weighting. This makes it suitable for measuring sounds that are more representative of overall sound energy, such as bursts of noise that may not have the same frequency characteristics.

Z-weighting, on the other hand, is essentially a flat weighting that does not apply any frequency filters. It provides a true representation of the sound levels across the entire audible spectrum. This is advantageous for scientific measurements or when assessing noise where a detailed frequency analysis is required.

Choosing the options A, C, and Z correctly reflects these commonly employed weighting networks, making it the most appropriate answer for the question. Other combinations would either omit one of the main types or include less relevant options.