QuantAsylum QA401 User
’s
Manual
Page
29
Weighting
Weighting can be applied to measurements if needed. While there are a lot of different weighting
functions defined, most are seldom used. The most commonly specified weighting function is A
Weighting, which attempts to adjust for the loudness as perceived by the human ear. Because the ear is
less sensitive at lower and higher frequencies, the weighting works to attenuate the values below
roughly 1 KHz and above 4 to 5 KHz or so.
On the QA401, weighting can be applied or removed by pressing the A weighting button, or the Off
button. When the Off button is selected, then no weighting is applied to the displayed data. When the A
button is selected, then the A weighting is applied. Notice that at 1 KHz, the A weighting has a gain of 0
dB, thus a 1 KHz signal will have the same amplitude whether or not weighting is applied.
Wikipedia lists the response curves for the various weighting function as follows:
