Custom‐Built Graphene Acoustic‐Absorbing Aerogel for Audio Signal Recognition.

Porous acoustic‐absorbing materials currently used to solve noise pollution mainly include polyurethane composite materials and porous fibers which are dedicated to achieving good noise reduction effects in a wide frequency range. Nevertheless, traditional porous acoustic‐absorbing materials face irreparable defects as required by the multifunction and high energy efficiency. The reason is nothing more than the internal microstructure of conventional acoustic‐absorbing materials is difficult to be precisely controlled by macroscopic operations, resulting in poor mass transfer capability and low energy conversion efficiency. In this work, by customized design of controlled mechanical foaming and atmospheric drying technique, a custom‐built graphene aerogel (cGA) as acoustic‐absorbing material with an acoustic absorption coefficient approaching 100% is prepared, which can efficiently absorb noise at an assigned frequency (2000–6000 Hz range) according to individual needs. Through simple stacking, cGAs expand from single‐frequency absorption to multi‐frequency high‐efficiency absorption. What is more significant is that a single aerogel has electrical signal responses of different intensities to sounds of different frequencies, which allows to build the aerogel into an acoustic detector to convert noise signals into electrical signals and realize the goal of sound fingerprint detection. [ABSTRACT FROM AUTHOR]