Influence of airflow resistance on acoustic behaviour of needle-punched nonwoven structures

Textile materials and structures have gained significant attention in the field of noise reduction due to their porosity, softness, and good acoustic absorption properties. Porous materials are an excellent example of passive materials, which reduces sound energy by dissipating heat energy due to the presence of void structure. In textiles, nonwovens are highly porous and less expensive materials compared to woven and knitted structures. In this research, flax, jute, and polyester nonwovens were used to study the effect of various parameters such as fiber fineness, fiber cross section, areal density, and punch density on the airflow resistivity of the nonwovens and in turn its influence on the sound absorption coefficient. It was observed that the acoustic performance of woven and nonwoven structures is mainly dependent on the porosity or bulk density of the structure which also influences the airflow resistivity of the fabrics. Therefore, the investigation of the airflow resistance of the nonwovens and its correlation with the sound absorption coefficient became an important part of this study. An instrument based on ISO 9053 standard was fabricated to measure the airflow resistivity. It was observed that the increase in the areal density leads to increase in the airflow resistance of the nonwoven. The airflow resistance increases as the mass density increases and porosity decreases. It was observed that the sound absorption coefficient and airflow resistance were directly proportional.