An experimental study on the effect of panel density on the sound absorption properties of a date palm fiber panel has been presented in this paper. The experiments were carried out by using impedance tube at the Acoustic Lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The date palm fiber was tested for densities of 77 kg/m3, 100 kg/m3 and 125 kg/m3.The results show that the values of absorption coefficient improve when increasing the density of the panel. Noise reduction coefficient (NRC) was computed to compare the performance of the palm date fiber samples for the different densities. The NRC increases by increasing the density.

Sound absorption of self-facing natural date palm fibershas been investigated.A single layer sample of the fibers was tested for its sound absorption properties. The sample was then faced with the originally date palm fiber netted structure. Experimental measurements were conducted on the impedance tube at the acoustic lab, Faculty of Engineering, UniversitiKebangsaan Malaysia, to determine the sound absorption coefficient.The single layer was also tested using an aluminum perforated plate, as facing, for comparison purposes.The results show a good improvement in the sound absorption for the self-facing panel for the whole frequency range. However, when using the aluminum perforated panel an improvement in the sound absorption was observed only above 2500 Hz. The effect of introducing air gap thickness was studied. The results show improvement for the sound absorption the low frequency.

In this study sound absorption properties of a single layer date palm fiber has been investigated. Experimental measurements were carried out using impedance tube at the acoustic lab, Faculty of Engineering, Universiti Kebangsaan Malaysia. A constant thickness sample was considered in this study.The results show that the values of absorption coefficient are small at low frequencies, rising with increasing frequency but exhibiting a significant peak. The low density of the sample is reflected in the overall sound absorption performance of the date palm fiber. An improvement in the sound absorption in the lower frequency range was achieved by backing the sample with air gap of different thicknesses of 10 mm, 20 mm and 30 mm. The increase in the air gap thickness moved the peaks toward lower frequencies and improved the low frequencies absorption. However, that increase coincided with reduction of absorption in medium frequency range and reduction in the absorption peak. A linear relationship was found between sound absorption peaks and the air gap thickness. The performance of the date palm fiber can be improved by increasing the density of the sample, using different sample thicknesses and adding perforated plates to the date palm fiber panel.

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