A-weighted decibel (dB(A)) is a sound-level measurement that applies a standardized frequency weighting intended to approximate the sensitivity of human hearing at moderate sound levels.
Human hearing does not respond equally to every frequency. A-weighting gives less emphasis to frequencies to which human hearing is less sensitive and is therefore commonly used when assessing environmental and occupational noise.
You may see sound levels reported as dB(A) rather than simply dB, particularly in environmental-health, workplace, and noise-regulation contexts.
dB(A) is particularly useful for many real-world noise assessments, but it does not capture every aspect of hearing or sound exposure. The duration and pattern of exposure also matter when considering potential hearing effects.
QUICK FACT
Two sounds with the same physical sound pressure level can have different perceived loudness because their frequencies differ.
COMMONLY CONFUSED WITH
- Decibel (dB): the broader unit, whereas dB(A) specifies a particular frequency-weighting method.
- Loudness: subjective perception rather than a direct physical measurement.
SEE ALSO