Investigation of wall surface material to reduce industrial noise

Abstract

Today noise control has become a major requirement with increasing of harmful effects for the people caused by industrial noise. This can be achieved when the intensity of sound is brought down to a level that is not harmful to human ears. .. This research was conducted to investigate the potential of using saw dust and coconut coir fiber as sound reducers. Wall tiles were made by using saw dust mixed with sand, a binding agent (i.e., cement, plaster of paris) and water. Tile properties (i.e., sawdust particle size, tile thickness, tile surface, binding agent, mix proportions) were changed and their effects were investigated. The moulds having the size of 20cm x 20cm x 2.5 cm, (length x width x height) were used to cast tiles. Panels were casted mixing coconut coir fiber with latex of rubber. Noise Reduction Co-efficient (NRC), which was the ratio of the intensity of sound absorbed and reflected by a tile to the intensity of incident noise of these tiles, was investigated by using an experimental setup including signal generator, speakers and noise level meter. A wooden box having 15cm xl5cm x 30cm width, height and length was also used to minimize the effects of surrounding noises. The readings were obtained at frequency intervals of 0.25 kHz for each tiles and panel. The NRC values obtained for above products ranged from 0.1 to 0.5 in the frequency range of 1-8 kHz. Saw dust and coconut coir fiber, which are natural material, can be used to manufacture tiles or panels with appreciable noise reduction properties.