Acoustic Glossary


 

Sound Energy : Definitions, Terms, Units, Measurements ..


Sound Energy

is the energy present in a sound field, the units are joules = watt seconds.

Sound Energy causes mechanical vibration in any medium through which a sound wave passes, including air and the human eardrum.

Sound Energy is related to the sound pressure, particle velocity and the density of the media.

Sound produces a relatively low level of energy when compared to other forms of energy


Sound Energy Level

is the logarithmic ratio of the sound energy to the reference sound energy

Sound Energy Level : Lw = 10 lg (w/wo) dB

The reference sound energy level : wo = 10-12 joules ≡ 0 dB

20 dB is a factor of 100
40 dB is a factor of 10000 etc.,


Sound Energy Density

is the time-averaged sound energy per unit volume (BS EN ISO 80000-8-2007)

Sound Energy Density symbol w and SI units J/m3 or W·s/m3

Sound Energy Density is also known as the Total Energy Density

Sound Energy Density Definition IEC 801-21-41

sum of the instantaneous (potential and kinetic) energy densities
 

Instantaneous Kinetic Sound Energy Density Definition IEC 801-21-40

half the product of the density of the medium and the square of the velocity of a particle in the said medium.
 

Instantaneous Potential Sound Energy Density Definition IEC 801-21-39

half the quotient of the square of the instantaneous sound pressure by the modulus of elasticity of the medium.

Sound Energy Density Level

is the logarithmic ratio of the sound energy density to the reference sound energy density

Sound Energy Density Level : LE = 10 lg (E/Eo) dB
The reference sound energy density level : Eo = 10-12 J/m3 ≡ 0 dB

20 dB is a factor of 100
40 dB is a factor of 10000 etc.,


Sound Energy Flux : q the SI units are W/m2 = J s/m2

Sound Energy Flux Definition IEC 801-21-37

time average product of the in-phase components of the instantaneous sound pressure and the volume velocity through the surface element considered.

Also known as Sound Power through a Surface Element


Sound Energy Flux Density Definition IEC 801-21-38

sound energy flux in a specified direction and sense through an area perpendicular to that direction, divided by the area.

Also known as Sound Intensity and Sound Power Density.


Sound Energy Flux Density Level Definition IEC 801-22-06

logarithm of the ratio of a given intensity of sound in a stated direction to the reference sound intensity. Such intensity level in decibels is ten times the logarithm to the base ten of the ratio.
Note : unless otherwise specified, the reference sound intensity is 1 pW/m2

Also known as the Sound Intensity Level

See also the IEC Definition of Level


See also Noise DoseSound Exposure

Related Terms : LeqSound IntensitySound PowerSound Pressure

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