| To be able to handle acoustic sizes better, the value is set in proportion with a reference size put in a logarithm. The levels as logarithm of a proportional size are dimensionless. The designation dB (Decibel ) is added.
The sound pressure level is set in proportion to the reference pressure p 0 = 2 x 10 -5 Pa and put in a logarithm. The following applies for the sound pressure level:
LP = Sound pressure level [dB]
 = Sound pressure [Pa]
p0 = Reference sound pressure [ 2 x 10-5 Pa ]
The other sizes in acoustics are treated in similar fashion. Acoustics uses almost only levels to indicate sizes. |