Supersonic acoustic intensity

A new acoustic quantity called the supersonic acoustic intensity vector is defined in this paper for application to measurements on plate and cylinderlike structures. As the name implies, the supersonic intensity is composed only of wave components which radiate to the far field (supersonic), with the nonradiating (subsonic) components eliminated. The normal component of this vector, measured in the extreme near field or on the surface of the structure, provides an accurate tool for locating regions (‘‘hot spots’’) on the structure which radiate to the farfield. Furthermore, the supersonic intensity provides an accurate quantification of these source regions, providing a ranking of the strength of the identified source regions as a function of frequency. This identification and ranking provides a powerful new tool in the understanding and control of radiated noise.