The Acoustic Power of a loudspeaker is the acoustic energy emitted from the speaker passing
through a specific plane which covers speaker’s entire frontal angle, in one second. More
specifically, acoustic power is the product of particle velocity, which is perpendicular to the plane,
and sound pressure. Acoustic power readings are obtained by calculation after measuring sound
pressure frequency response at multiple points on a specific plane in front of a speaker.
Every sound has a source. The sound emitted from the sound source travels in all directions
through air, similar to ripples on the surface of water after dropping a stone. Just as the ripples
carry kinetic energy, the sound waves carry acoustic energy. The acoustic energy at a moment is
acoustic power. The sound we hear in the natural world is the sum of the acoustic energy arriving
f rom al l directions, converted to sound pressure at ears.
The Necessity of Using Acoustic Power
When we hear the sound from the speakers, we are hearing the acoustic energy arriving to our ears
(converted to the sound pressure) from the multiple directions as both on-axis and off-axis sound.
Traditional equalization is based on one-point SPL on-axis measurement and does not correspond
to the sound we actually hear at the different locations in the room. Therefore, we should equalize
the acoustic power instead of the one-point SPL on axis.