APPLICATION OF SOUND INTENSITY METHOD TO NOISE CONTROL ENGINEERING AND BUILDING ACOUSTICS

Sound pressure and particle velocity are the most essential quantities prescribing a sound field; they correspond to voltage and electric current respectively, in electric system. As electric power is the product of voltage and electric current, sound intensity is the product of sound pressure and particle velocity and it means the acoustic power passing through a unit area in a sound field. Although the definition of sound intensity is very simple as mentioned above, the method of measuring this quantity has not been realized for a long time, because it has been very difficult to measure the particle velocity simultaneously with the sound pressure. Owing to the recent development of such technologies as transducer production and digital signal processing, it has finally been realized. According to the sound intensity(SI) method, the sound power flow in an arbitrary sound field can be directly measured as a vector quantify. In this paper, the principle of the SI method is briefly explained at first and some examples of its application made in the author's laboratory are introduced.