The advent of sound intensity measurement systems in the beginning of the 1980s has had a significant influence on noise control engineering. Today sound intensity measurements are routinely used in the determination of the sound power of machinery and other sources of noise in situ. Other important application of sound intensity include the identification and rank ordering of partial noise sources, visualisation of sound fields, determination of the transmission losses of partitions, and determination of the radiation efficiencies of vibrating surfaces. Sound intensity is also an important research tool.

 

This paper summarises the basic theory of sound intensity and its measurement and gives an overview of the state of the art in the various areas of application, with particular emphasis on recent developments.