dB(A)

A Weighting curve is a graph that is used to 'weight' measured values of a variable according to their importance in relation to some outcome. The most commonly know example is in sound level measurement where a specific set of weighting curves known as A, B, C and D weighting are often used. Measurements of sound intensity do not correspond to perceived loudness because the human ear is less sensitive at low and high frequencies, with the effect more pronounced at lower sound intensities. The four curves are applied to the measured intensity, for example by the use of a weighting filter in a sound level meter, to arrive at readings of loudness in Phons or in deciBells (dB) (see A-weighting).
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