Sound absorption properties and mechanism of multi-layer micro-perforated nanofiber membrane

Aiming at achieving low-frequency and broadband sound absorption under the premise of light and thin layers, in this paper, polyvinyl butyral (PVB) nanofiber membranes were micro-perforated and then combined sequentially to prepare multi-layer micro-perforated nanofiber membrane (MPNM) for acoustic noise reduction. It was demonstrated that the multi-layer MPNM exhibited a high absorption (constantly over 50%) in the frequency of 480-2500 Hz. In addition, the established theoretical model of the sound absorbing coefficient can accurately predict the sound absorption performance of the structure with different layers, which can provide a theoretical foundation for the design of the structure of the nanofibrous membrane acoustic absorber. Based on the proposed acoustic model, the relationships between the absorption properties and the parameters were investigated, and it was found that the effective acoustic absorption frequency range and acoustic absorption coefficient curve of the multi-layer MPNM were closely related to the size and arrangement of hole diameter, perforation rate, fiber membrane thickness, and cavity depth. Optimization of the structural parameters utilizing algorithms can achieve superior sound absorption performance, with an average absorption coefficient of 0.81 in the frequency of 100-2500 Hz. This study provides a theoretical and experimental basis for the development of low-frequency sound-absorbing materials and is of great significance for optimizing the acoustic performance of nanofiber membranes and expanding their applications in various acoustic engineering applications.