Sound energy density

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Not to be confused with Sound pressure.
Sound measurements
 Sound pressure  p, SPL
 Particle velocity  v, SVL
 Particle displacement  δ
 Sound intensity  I, SIL
 Sound power  P, SWL
 Sound energy  W
 Sound energy density  w
 Sound exposure  E, SEL
 Acoustic impedance  Z
 Speed of sound  c
 Audio frequency  AF
 Transmission loss  TL

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[edit]

Sound energy density, denoted w, is defined by

w = \frac{p v}{c}


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).

Relationships with other quantities[edit]

Sound energy density is related to sound intensity:

w = \frac{I}{c},


Sound energy density is related sound power:

w = \frac{P}{Ac},


  • P is the sound power;
  • A is the area.

See also[edit]

External links[edit]