A Lightweight Fabric-based Breathable Metamaterial for Low Frequency Noise Insulation

The common sound insulation material existing in the market are mainly in the form of porous or fibrous material. It is bulky for insulating low frequency noise (<500Hz) and unfavorable to equip on wearable products or industrial machines for low frequency noise insulation. This project is a response to the rapid growth of environmental noise pollution due to increasing human activities as per the alarm from the World Health Organization (WHO).

• The metamaterial uses self-developed energy absorption coating to absorb low frequency sound. It makes use of shearing thickening sluid, a fluid that acts like solid for protection when experiencing shear force (e.g. noise).
• The installation is fabric-based, replacing thick sponge or metal louver as sound barrier. Metamaterial-coated cotton fabric is thinner than sponge but with higher sound transmission loss (i.e. better noise reduction performance).
• A tension control is equipped to adjust sound insulation performance.

• Simple set-up, lightweight and easily adaptable to various sources of noise for broadband frequency absorption
• Good air permeability (1.5cm³/cm²/sec) for thermal control and heat dissipation of machines (complying ASTM D737-18 standard on air permeability for textile fabrics)

• 49th International Exhibition of Inventions of Geneva (2024) - Silver Medal

• The fabric-based soft acoustic metamaterial can be applied to produce sound insulation for various sources of low frequency noise.

• PCT/CN2024/072237 (PCT)