Topic summary
Weighting
Extracted from the Wikipedia article Frequency Weighting (spectral analysis).
Weighting and loudness
In the measurement of loudness, for example, a weighting filter is commonly used to emphasise frequencies around 3 to 6 kHz where the human ear is most sensitive, while attenuating very high and very low frequencies to which the ear is insensitive. A commonly used weighting applicable to human hearing is the A-weighting curve, which results in units of dBA sound pressure level. Because the frequency response of human hearing varies with loudness, the A-weighting curve is correct only at a level of 40-phon and other curves known as B-, C- and D-weighting are also used, the latter being particularly intended for the measurement of aircraft noise.