The Power of Sound

The Power of Sound explains sound power, also called acoustic power, as the rate at which sound energy is emitted, reflected, transmitted or received over time. It defines the quantity through a surface by combining sound pressure with the component of particle velocity normal to that surface, then integrating the result across it. The book distinguishes sound power from sound pressure: sound pressure describes the sound field at a particular point in space, while sound power belongs to the source itself and is the total power that source emits in every direction. It also notes that, for a sound source, sound power does not depend on the room or on distance.

The text uses the technical language of acoustics, including the watt as the SI unit of sound power. It also identifies sound power passing through an area as sound flux or acoustic flux through that area.