SOUND ABSORPTION PERFORMANCE OF OIL PALM EMPTY FRUIT BUNCH FIBERS

The conventional acoustic absorbers are made from synthetic materials which are not only causing global warming and pollutions during its production, but also harmful to human. Thus, scientists have turned their attention to find sustainable and 'green' materials which have the potential to replace synthetic materials. Oil Palm Empty Fruit Bunch (OPEFB) fiber is a biodegradable material and is available in abundance quantity as agricultural waste in Malaysia. In this study, sound absorption performance of OPEFB fiber is investigated. The impedance tube testing according to ISO 10534-2 was conducted to measure the sound absorption coefficient. Samples of raw OPEFB fibers with different masses and thicknesses are tested. In the experimental work, the effects of fiber density (or fiber mass), thickness and air gap on sound absorption coefficient are explored. Increment in fiber density showed improvement of sound absorption performance in high frequency region. The increase in thickness and application of air gap enhanced the sound absorption performance, especially at lower frequency region. At thickness of 50 mm, OPEFB fibers with density of 292 kg/m(3) showed good sound absorption performance where the sound absorption coefficient achieved 0.9 in average above 1 kHz. Comparison with industrial acoustic rock wool showed that OPEFB fibers possess similar sound absorption performance at the same thickness of 50 mm Delany-Bazley model is used to validate the experimental work. It is found that the mathematical model is able to predict the trend of the sound absorption performance curve with minor deviation.