Sound energy density
Appearance
Sound measurements | |
---|---|
Characteristic | Symbols |
Sound pressure | p, SPL, LPA |
Particle velocity | v, SVL |
Particle displacement | δ |
Sound intensity | I, SIL |
Sound power | P, SWL, LWA |
Sound energy | W |
Sound energy density | w |
Sound exposure | E, SEL |
Acoustic impedance | Z |
Audio frequency | AF |
Transmission loss | TL |
![]() | It has been suggested that Sound energy density level be merged into this article. (Discuss) Proposed since March 2015. |
Sound energy density or sound density is the sound energy per unit volume. The SI unit of sound energy density is the pascal (Pa), that is the joule per cubic metre (J/m3) in SI based units.
Mathematical definition
Sound energy density, denoted w, is defined by
where
- p is the sound pressure;
- v is the particle velocity in the direction of propagation;
- c is the speed of sound.
The terms instantaneous energy density, maximum energy density, and peak energy density have meanings analogous to the related terms used for sound pressure. In speaking of average energy density, it is necessary to distinguish between the space average (at a given instant) and the time average (at a given point).