Flexible sound insulator with subwavelength film structure for noise reduction

Decorative textiles such as curtains and wall-cloth have the characteristics of sound absorption and sound insulation to reduce the external noise annoyance, which has been expected by the researcher. In this study, a film with controllable thickness was constructed on the woven fabric's surface by ultrasonic precision spraying to reduce noise. Influences of fabric structure, film thickness, filler distribution, filler content and type on the sound transmission loss (STL) of the flexible sound insulator were investigated. From the results, the film sealed the tiny pores on the fabric surface and increased the reflection of sound energy, which leading to excellent sound insulation performance of the structure. Furthermore, sound energy can be effectively absorbed by this structure. When the thickness of the film was about 50 μm and the filler was vermiculite, the flexible sound insulator exhibited the best sound insulation performance: the STL reached 9.5 dB, which was about three times that of the substrate. It was worth noting that the STL of the sound insulator can be significantly changed by adjusting the distribution of filler. The thickness of this new type material was similar to that of wall-cloth, but its STL was much better than the wall-cloth, which was equivalent to the STL of the thick curtain. This will open up the application of thin fabrics in the field of acoustic protection.