Measuring and modelling the effect of base zone on sound absorption of persian rug

The aim of this study is to investigate the role of base zone on rug sound absorption and to predict the acoustic behavior of typical Iranian rugs using a mathematical model. For this purpose, four rug samples (1.5 cm thickness) were produced with different base structures, so that the base warp yarns are divided into two equal groups and arranged from each other at a different adjustable distance (0.0, 0.1, 0.2 and 0.3 cm). Sound absorption measurements were carried out using an impedance tube. Then, in order to focus on the base zone and to separate the piles contribution from the global rug sound absorption, the pile yarns were shaved from all samples and the non-piled samples were measured again. The five-parameter model of Johnson-Champoux-Allard (JCA model) was fitted to experimental data, assuming the rug is a two-layer (pile + base zone) porous absorber. The agreement between the model and the experiments is satisfactory. This optimized model can be used to predict the sound absorption coefficient of Iranian rugs. The results indicate that the rug base plays an important role in the overall rug sound absorption and that the air gap between the two groups of warp yarn improves the rug sound absorption.