Investigation of Eigen Frequencies and Eigen Modes of Rooms Due To Low Frequency Noise

Abstract

There are rapid social, economic and technological changes, and the numbers of industrial noise sources are growing higher which are affecting a large number of individuals in past decades. Low frequency noise (LFN), the frequency of which ranges below 250 Hz, is generated by many machines commonly used in the working environment, such as fans, ventilation systems, heat pumps, diesel engines, blowers, compressors, and so on. Sound pressure levels (SPLs) at low frequencies (20 to 200 Hz) are strongly dependent on measurement position in normal-sized rooms. The variation of SPL can be above 20 dB between different measurement locations. Resonance frequency, called modes are present in every room. For low frequency modes we have to investigate the resonance behavior of room as a whole. This paper demonstrates the use of COMSOL multiphysics to predict the acoustic response of a room such as laboratory in Shopra Elkheima electrical power plant.