Sound Power


Sound power or acoustic power Pac is a measure of sonic energy E per time t unit. It is measured in watts and can be computed as sound intensity (I) times area (A):

P_{\mathrm{acoustic}} = I \cdot A

When the acoustic wave approaches the measurement surface at an angle, the area is taken as the area times the projection of the wave direction upon the normal of the surface.

The difference between two sound powers can be express in decibels (logarithmic measure) using this equation:

L_\mathrm{w}=10\, \log_{10}\left(\frac{P_1}{P_0}\right)\ \mathrm{dB}

where, are the sound powers. The sound power level SWL, LW, or LPac of a source is expressed in decibels (dB) relative to a reference sound power. In air this is normally taken to be = 10−12 watt, that is 0 dB SWL.

Unlike sound pressure, sound power is neither room dependent nor distance dependent. Sound power belongs strictly to the sound source. Sound pressure is a measurement at a point in space near the source, while sound power is the total power produced by the source in all directions.

Read more about Sound Power:  Table of Some Sound Sources, Sound Power Measurement, Sound Power With Plane Sound Waves, Sound Power Level

Famous quotes containing the words sound and/or power:

    “I thought when I was a young man that I would conquer the world with truth. I thought I would lead an army greater than Alexander ever dreamed of. Not to conquer nations, but to liberate mankind. With truth. With the golden sound of the Word. But only a few of them heard. Only a few of you understood. The rest of you put on black and sat in chapel.”
    —Philip Dunne (1908–1992)

    “The power of consumer goods ... has been engendered by the so-called liberal and progressive demands of freedom, and, by appropriating them, has emptied them of their meaning, and changed their nature.”
    —Pier Paolo Pasolini (1922–1975)