Experimental study on the effect of compression on the sound absorption of date palm fibers

This paper presents an experimental investigation on the effect of compression on the sound absorption properties of a date palm fiberl. The experiments were carried out using an impedance tube. The material was tested for 1, 1.3 and 2.5 compression rates. The results show that the values of absorption coefficient for the uncompressed sample (30 mm) are small at low frequencies, rising with increasing frequency and exhibiting a significant peak. When the sample is compressed to 23 mm or nominal rate of 1.3 the sound absorption improved after frequency 2500 Hz with a slight decrease in the range of 1500 Hz and 2500 Hz. However, a further compression to 12 mm or increasing the nominal compression rate to 2.5 reveals an overall lower performance of the sample compared with the compression rate of 1.3. Simulation was performed using Delany and Bazley model for sound absorption of the panel using modified and unmodified flow resistivity. The simulation results show that the trend of the panel in sound absorption when using the modified flow resistivity is more closed to the trend of the experimental results.