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How does an A-weighted decibel measurement account for human hearing?

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A-weighted decibel (dBA) measurements account for human hearing by using frequency filters to adjust sound-level meter readings to match the ear's varying sensitivity to different pitches.1

Because human hearing is nonlinear, people generally perceive high-frequency sounds as louder than low-frequency sounds of the same amplitude. To reflect this, the A-weighted filter introduces a frequency-dependent weighting factor that reduces the influence of low-frequency components, yielding a response that more closely approximates the subjective perception of loudness by the human ear.12

This scale is the most common standard for measuring ambient community noise and is recognized internationally for assessing noise in work environments to help prevent hearing loss. While other scales exist—such as the C-weighted (dBC) scale, which is sometimes used for impact noises like gunfire—the A-weighted scale remains the primary tool for describing how complex noises affect people.12