Which statement best describes A-weighting in sound measurement?

• A. It measures impulse noise exclusively
• B. It exactly matches the human ear at all frequencies
• C. It approximates the equal loudness curve and the ear's response to different frequencies
• D. It applies only to low-frequency sounds

Answer: (C)

A-weighting is a frequency weighting applied to sound level measurements to reflect how humans perceive loudness. The curve adjusts measurements by giving more emphasis to mid frequencies where the ear is most sensitive and reducing the contribution from low and very high frequencies. This approach is designed to align with the ear’s varying sensitivity across the audible range, which is captured by the equal-loudness contours developed for human hearing at typical listening levels. Because of this, a weighted value (dBA) correlates more closely with perceived loudness than a simple, unweighted SPL.

It’s not about measuring impulse noise exclusively, and it isn’t an exact match to the ear across all frequencies. It’s a practical approximation used for standardized noise measurements. It also isn’t limited to low-frequency sounds; the weighting applies across the spectrum, with greater attenuation of frequencies outside the ear’s peak sensitivity.