A compact method for efficient evaluation of acoustic absorbers with submicron materials.

Materials with submicron or nano-scale features possess unique physical properties and are well-suited for application in noise reduction. To date, experimental characterization of the sound absorbing ability of the submicron/nano materials is still a challenging task, because the measuring of sound absorptivity usually requires bulky samples, while the preparation of large quantities of submicron/nano materials or structures is generally costly and laborious. In this work, an acoustic testing method is proposed to evaluate the acoustic absorptivity of submicron/nano materials using small samples. Based on the transfer-matrix algorithm, the method establishes correlations among acoustic-related parameters of a large sensor fixture and a small sample holder. A proof-of-principle experimental setup was developed to test absorbers with well-known acoustic behavior to verify accuracy of the method. Finally, the sound absorption properties of two submicron materials are characterized, with one comprising dispersed silver submicron fibers and the other comprising electrospinning submicron fibers. The results indicate that acoustic absorption coefficients can be effectively retrieved using only 1/200 of the amount of materials that are typically required in the standard test.