Sound pressure level Lp

Lp=10lg (p/p0)^2 dB where p is the sound pressure and the reference value in airborne acoustics is p0 = 20 μPa. Note 1 to entry: Because of practical limitations of the measuring instruments, p2 is always understood to denote the square of a frequency-weighted, frequency-band-limited or time weighted sound pressure or both. If specific frequency and time weightings, as specified in IEC 61672‑1:2002, or specific frequency bands or both are applied, this should be indicated by appropriate subscripts.