ABSTRACT
When specifying interior noise level objectives for different areas of a building, many factors have to be considered. In general, the ventilation system noise should be low enough so as not to interfere with speech or other communicative sounds. All air-conditioning and ventilation systems have to supply air to many areas of a building, and the major source of noise and vibration is usually associated with the supply fan. In modern ventilation systems, two types of fans, centrifugal and vane axial, are employed in approximately equal numbers. Acoustically lined plenum chambers are very frequently used in large air-conditioning or ventilation systems where considerable attenuation is required to reduce the sound power produced by a fan. Since the number of high velocity ventilation and air-conditioning systems in use is rapidly increasing, it is essential to be able to obtain a reasonably accurate estimate of the sound power level of such generated noise at common points within the system.
