- Sound power
Sound measurements
Sound power or acoustic power "P"ac is a measure of sonic
energy "E" pertime "t" unit.It is measured in
watt s, orsound intensity "I" times area "A"::The measure of a ratio of two sound powers is:
where:"P"1, "P"0 are the sound powers.
The
sound power level PWL, LW, or LPac of a source is expressed indecibel s (dB) and is equal to 10 times the logarithm to the base 10 of the ratio of the sound power of the source to a reference sound power. It is thus a logarithmic measure.The reference sound power in air is normally taken to be 10−12 watt = 0 dB SWL.
Sound power is neither room dependent nor distance dependent. Sound power belongs strictly to the sound source.
Table: Sound power and sound power level of some sound sources
:
Usable music sound (trumpet) and noise sound (excavator) both have the same sound power of 0.3 watts, but will be judged psychoacoustically to be different levels.
ound power with plain sound waves
Between sound power and other important acoustic values there is the following relationship:
where:
External links
* [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]
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