Sound power level

Sound power level or acoustic power level is a logarithmic measure of the sound power in comparison to a specified reference level.

The measure of a ratio of two sound powers is Sound Power, Sound Intensity, and the difference between the two - Indiana University's High Energy Physics Department Georgia State University Physics Department - Tutorial on Sound Intensity

L_\mathrm{W}=10\, \log_{10}\left(\frac{W_1}{W_0}\right)\ \mathrm{dB}

where W₁ and W₀ are the powers.

The sound power level is given the symbol L_w or SWL and is measured in "dBW", which stands for decibel with the suffix for watts. Decibels are dimensionless. SPL stands for sound pressure level, and is not the same thing.

If W₀ is the standard reference sound power, where

W_0=10^{-12}\ \mathrm{W}

(W = watt), then instead of "dB", dB SWL is used. (SWL = sound power level).

Table: Sound power level and sound power of some sound sources

{| class="wikitable"

! Situation
and
sound source !! sound power
P_ac
watts !! sound power
level L_w
dB re 10^-12 W Rocket engine 1,000,000 W 180 dB Turbojet engine 10,000 W 160 dB Siren 1,000 W 150 dB Heavy truck engine or
loudspeaker rock concert 100 W 140 dB Machine gun 10 W 130 dB Jackhammer 1 W 120 dB Excavator, trumpet 0.3 W 115 dB Chain saw 0.1 W 110 dB Helicopter 0.01 W 100 dB Loud speech,
vivid children 0.001 W 90 dB Usual talking,
Typewriter 10⁻⁵ W 70 dB Refrigerator 10⁻⁷ W 50 dB (Auditory threshold) 10^-12 W 0 dB

The Trumpet and excavator both have the same sound power of 0.3 watts, but may be judged psychoacoustically to be different levels. As noise is unwanted sound the trumpet can be percieved to be acceptable when listened to as music but at the same sound power level may be percieved to be noisy if one is trying to sleep.

Measurement | Power | Sound

Schallleistungspegel | Nivel de potencia acústica

Table: Sound power level and sound power of some sound sources

References

External links

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Table: Sound power level and sound power of some sound sources

References

External links