Hladina akustického tlaku
livello di pressione sonora
miary wielkości ilorazowych
niveau de pression acoustique
nível de pressão acústica
уровень звукового давления
Sound pressure level ($SPL$) or sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level.
Applicable units are those of quantitykind:SoundPressureLevel
http://en.wikipedia.org/wiki/Sound_pressure#Sound_pressure_level
$L_P = 10 \log_{10} \frac{p^2}{p_0^2} dB$, where $p$ is sound pressure and the reference value in airborne acoustics is $p_0 = 20 \mu Pa$.