Effects of air gap, fibre type and blend ratio on sound absorption performance of needle-punched non-woven fabrics

This article reports a study on the effect of different natural fibres, their blend ratios and varying air gaps between a needle-punched non-woven fabric and polystyrene backing on the sound absorption coefficients of the needle-punched non-woven fabrics. These parameters as well as their interactive effects were studied by variance analysis. The air gap varied from 0 to 25 mm in 5 mm increments; three natural fibre types (agave, flax and waste wool) were used; each one blended with polyester fibres in three blending ratios. The univariate test of significance showed that all three parameters and two of the three two-way interactions effects on sound absorption coefficients were significant. Only two-way interaction effect between blend ratio and air gap on sound absorption coefficient was not significant. It was found that the sound absorption coefficients increased with an increase in air gap size up to 15 mm, after which they decreased slightly as the air gap was increased further to 25 mm. In addition, the non-woven fabrics produced from the blend of waste wool and polyester fibres achieved the highest sound absorption coefficients than those of the other two natural fibres, and generally, the sound absorption coefficients increased with the increase in polyester fibre content in each blend studied.