The **sound energy density level** gives the ratio of a sound incidence as a sound energy value in comparison to a reference level of 0 dB (DIN 45630). It is a logarithmic measure of the ratio of two sound energy densities.

The energy produced by vibrations is known as sound

L
(
E
)
=
10
log
10
(
E
1
E
0
)
d
B
where *E*_{1} and *E*_{0} are the energy densities. The unit of the sound energy density level is the decibel (dB).

If *E*_{0} is the standard reference sound energy density of

E
0
=
10
−
12
J
m
3