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

Abstract

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.

Acoustical behavior of camellia sinensis/ananas comosus fiber based uni-directional corrugated panel for sound damping application

“…Similar results are obtained by increasing the material's thickness, which can improve the sound absorption coefficients at low, middle, and high frequencies due to an increase in sound energy losses. As observed in other studies [28], for achieving higher sound absorption coefficients at low frequencies by using a thicker material, it can simply be altered by incorporating an air gap, thereby reducing the number of fibers required. Consequently, this investigation has once again proved that if the material's thickness increases with an increase in airgap, the sound absorption coefficient increases.…”

Research progress of piezoelectric polymer PVDF in sound absorption technology

“…Porous sound-absorbing materials are one of the most widely used sound-absorbing materials, which have good sound-absorbing performance in the highfrequency band, including fibers, [99][100][101][102] foam, [103][104][105][106] and particle [107][108][109][110] sound-absorbing materials. Within porous materials, there are a lot of tiny pores that link to the outside world and each other.…”

The sound absorption performance of the highly porous silica ceramics prepared using freeze casting method

“…It is widely believed that the presence of air gap in the back of porous sound absorbers benefits their sound absorption performance. [42][43] Seddeq et al 44 found that the inserting of air gaps and its thickness showed evident effect on the sound absorption properties including absorption peak and absorption curves of the porous fibrous materials. Thus, air gaps with different thickness are set at the back of the sample to investigate their effect on the sound absorption properties.…”