Measuring and modeling the effect of density and pile height on sound absorption of double base Persian rug

The purpose of this study is to investigate the role of density and pile height on sound absorption coefficient in Double Base Persian (DBP) rug and possibility of prediction the acoustic behavior of DBP rug using the mathematical model. For this aim, in the first step, three double base rug samples were produced at different base densities (2, 4, and 6 warp yarn/cm) and the sound absorption coefficient of samples was measured with Impedance tube in two thicknesses (15 & 13 mm) to study the pile height effect. Moreover, the sound absorption of the double base zone was also measured by shaving off the pile from the double base rug samples. Three rug samples at different base densities were produced with very thin warp and weft yarns to avoid the base effect in this sample. Besides, the macroscopic empirical model (Johnson–Champoux–Allard (JCA)) was implemented on obtained data. The results showed that the sound absorption of the double base rug samples increases with increasing the pile height and base density. The role of the base zone in the sound absorption of the rug is bolder than the pile zone. What leads to improve the rug sound absorption by increasing density is increasing the sound absorption of base zone and the pile density changes do not play a major role in increasing the rug sound absorption. In addition, by assuming DBP rugs as a two-layer porous (pile + base zone) absorber, JCA model shows a good consistency with experimental data.