The sound pressure level which has been filtered or weighted to quantitatively reduce the effect of low frequency noise. It was designed to approximate the response of the human ear to sound. A-weighted sound pressure level is measured in decibels with a standard sound level meter which contains the "A" weighting network. A-weighted decibels are abbreviated dBA and indicates approximate relative loudness.
A measurement representing a sound generally as the human ear hears it by filtering out as much as 20 to 40 decibels of sound below 100 hertz (Hz). Used for aircraft noise evaluations.
A measure of sound pressure level designed to reflect the response of the human ear, which does not respond equally to all frequencies. To describe sound in a manner representative of the human ear's response it is necessary to reduce the effects of the low and high frequencies with respect to the medium frequencies. The resultant sound level is said to be A-weighted, and the units are dBA. The A-weighted sound level is also called the noise level. Sound level meters have an A-weighting network for measuring A-weighted sound levels.