FWIW, three dBA is twice the sound power, but is not perceived as twice as loud by the human ear. Our ears are also logarithmic devices, meaning a 10 dBA increase sounds twice as loud even though it is ten times the sound power level.
dB = 10 * LOG (sound power / 10^(-12)) where sound power is in watts.
dBA merely adds or subtracts a dB or few based on the primary frequency to correspond to the ear's non-linear (vs frequency) sensitivity.
|