Sound energy density
Sound quantities |
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The sound energy density (symbol E or w ) is a measure to describe the sound energy present at a certain location in the sound field . It is a sound energy quantity . The associated logarithmic quantity is the sound energy density level.
definition
The sound energy density E is the sound energy per volume unit:
It gives information about the sound energy W at a certain location of a sound field and is its energy density .
The unit of sound energy density is joules per cubic meter (J / m³).
In the special case of the even advancing wave, the time-averaged sound energy density is:
- ,
where I is the sound intensity and c is the speed of sound .
Sound energy density level
Occasionally the sound energy density is also given in the form of a sound energy density level L _{E} in decibels (dB):
The reference value is defined as J / m³ or W · s / m³.
Relationships in the plane wave
Further formulas for the sound energy density for flat, progressing sound waves:
Where:
symbol | units | meaning |
---|---|---|
E. | W · s / m ^{3} | Sound energy density |
ξ | m , meter | Sound deflection |
= 2 · · f | rad / s | Angular frequency |
ρ | kg / m ^{3} | Air density , density of the air (of the medium) |
v | m / s | Speed of sound |
a | m / s ^{2} | Sound acceleration |
p | Pascal | Sound pressure |
f | hertz | frequency |
Z = c ρ | N · s / m ^{3} | Characteristic acoustic impedance, acoustic field impedance |
I. | W / m ^{2} | Sound intensity |
c | m / s | Speed of sound |
P _{ak} | W, watt | Sound power |
A. | m ^{2} | Transmitted surface |
Web links
- Sound energy density and the relationship between the acoustic quantities in the case of flat, progressing sound waves (PDF; 109 kB)
- Sound quantities, their levels and the reference value - conversions, calculations and formulas
Individual evidence
- ↑ DIN 1320: Acoustics: Terms . Edition 1997-06.