A decibel (dB) is a logarithmic unit used to express the level of a sound or, more precisely, the ratio between measured sound quantities.
The decibel scale is logarithmic rather than linear. This means that an increase of several decibels can represent a substantial increase in sound intensity, so 100 dB is not simply “twice as loud” as 50 dB.
In everyday health communication, decibels are commonly used to describe sound levels and help estimate potential hearing risk when considered together with exposure duration.
A decibel value is incomplete without knowing what quantity and reference are being used. For sound, different measurements can therefore be expressed using different forms of decibel notation.
QUICK FACT
dB is not a single universal measure of “loudness.” The reference and measurement method matter.
COMMONLY CONFUSED WITH
- dB(A): a sound-level measurement using A-weighting to approximate the frequency sensitivity of human hearing.
- Loudness: a person’s perception of how loud a sound seems.
SEE ALSO
