Editing Sound energy density

{{distinguish|Sound pressure}}
{{Sound measurements}}

'''Sound energy density''' or '''sound density''' is the [[sound energy]] per unit volume. The [[International System of Units|SI unit]] of sound energy density is the [[Pascal (unit)|pascal]] (Pa), which is 1&nbsp;kg⋅m<sup>−1</sup>⋅s<sup>−2</sup> in SI base units or 1 [[joule]] per [[cubic metre]] (J/m<sup>3</sup>).<ref name=SIUnits>{{cite report | editor-last=Newell | editor-first=David B | editor-last2=Tiesinga | editor-first2=Eite | title=The international system of units (SI) | publisher=National Institute of Standards and Technology | publication-place=Gaithersburg, MD | year=2019 | doi=10.6028/nist.sp.330-2019 | url = https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.330-2019.pdf}}</ref>{{rp|at= Section 2.3.4: Derived units, Table 4}}

==Mathematical definition==
Sound energy density, denoted ''w'', is defined by
:<math>w = \frac{p v}{c}</math>
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).

==Sound energy density level<!--'Sound energy density level' redirects here-->==
The '''sound energy density level'''<!--boldface per WP:R#PLA--> gives the ratio of a sound incidence as a sound energy value in comparison to the reference level of 1 pPa (= 10<sup>−12</sup> pascals).<ref>[[Deutsches Institut für Normung]], ''Grundlagen der Schallmessung; Physikalische & subjektive Größen von Schall, Physical & subjective magnitudes of sound'', Norm, Standard, № [https://dx.doi.org/10.31030/1234608 DIN 45630‑1:1971‑12] (Berlin: Beuth, 1971‑12).</ref> It is a logarithmic measure of the ratio of two sound energy densities. The unit of the sound energy density level is the [[decibel]] (dB), a non-SI unit accepted for use with the SI Units.<ref name=SIUnits />{{rp|at=| Chapter 4: Non-SI units that are accepted for use with the SI, Table 8}}

The sound energy density level, ''L''(''E''), for a given sound energy density, ''E''<sub>1</sub>, in pascals, is 
:<math>
L(E) = 10\, \log_{10}\left(\frac{E_1}{E_0}\right) ~ \text{dB}
</math>,

where ''E''<sub>0</sub> is the standard reference sound energy density<ref name="DIN1320">[[Deutsches Institut für Normung]], ''Akustik—Begriffe, Acoustics—Terminology'', Norm, Standard, № [https://dx.doi.org/10.31030/1544140 DIN 1320:2009-12] (Berlin: Beuth, 2009‑12).</ref>

:<math>
E_0 = 10^{-12}\ \mathrm{Pa} 
</math> .

==See also==
*[[Particle velocity level]]
*[[Sound intensity level]]

==References==
<references/>

==External links==
*[http://www.sengpielaudio.com/calculator-soundlevel.htm Conversion: sound intensity to sound intensity level]
*[http://www.sengpielaudio.com/calculator-ak-ohm.htm Ohm's law as acoustic equivalent - calculations]
*[http://www.sengpielaudio.com/RelationshipsOfAcousticQuantities.pdf Relationships of acoustic quantities associated with a plane progressive acoustic sound wave - pdf]

[[Category:Acoustics]]
[[Category:Sound]]
[[Category:Sound measurements]]
[[Category:Physical quantities]]