ABSTRACT
This chapter talks about sound that propagates in a compressible medium such as air, which is known as airborne sound. Quantification of airborne sound is an important step in identifying frequency and magnitude of the dynamic pressure. A microphone is the transducer that is used for measuring dynamic pressure. The chapter discusses the time-averaged sound pressure levels that are important for computing exposure of industrial workers to airborne sound and for evaluating environment noise pollution. A typical sound signal can have a combination of several frequencies in the audible frequency range. An A-weighted sound pressure level is the quantity measured by a calibrated microphone and amplifier of a sound level meter, modified so the frequency response follows approximately the equal loudness curve of 40 phons. In order to determine sound intensity, it is necessary to measure the sound pressure and particle velocity simultaneously at the same point in the sound field.
