Effects of total surface area and fabric density on the acoustical behavior of traditional thermal‐bonded highloft nonwoven fabrics

Nonwoven fabrics are ideal materials for use in acoustical insulation products because they have a high total surface area, which is directly related to the denier and cross‐sectional shape of the fiber. The smaller the denier, the more fibers for the same material density, the higher the total fiber surface area is. This results in a greater opportunity for interaction between the sound wave and the fibers in the structure. Another important parameter is the density of the nonwoven material, which affects the geometry and the volume of the voids in the structure. The acoustical properties of fabric materials are measured using one of two methods: the impedance tube method and the reverberation room test method. The impedance tube method uses very small test samples (5–15 cm), whereas the reverberation room test method requires large test samples and is expensive to set up. For making comparative analysis of the test samples and overcoming the disadvantages of the current test methods, a direct comparative acoustical properties measurement device has been developed and fabricated in the School of Materials Science and Engineering at Clemson University in an attempt to overcome some of the disadvantages of the other method.