Sound power or
acoustic power is the rate at which
sound energy is emitted, reflected, transmitted or received, per unit time. The
SI unit of sound power is the
watt (W). It is the power of the sound force on a surface of the medium of propagation of the sound wave. For a sound source, unlike sound pressure, sound power is neither room-dependent nor distance-dependent. Sound pressure is a measurement at a point in space near the source, while the sound power of a source is the total power emitted by that source in all directions. Sound power passing through an area is sometimes called
sound flux or
acoustic flux through that area.