Structure-sound absorption property relationships of electrospun thin silica fiber sheets: Quantitative analysis based on acoustic models

Abstract In order to determine the sound absorption mechanism and characteristics of nonwoven sheets composed of thin silica fibers quantitatively, their structure and acoustic properties were characterized and the influence of their structure on the sound absorption characteristics were investigated based on conventional acoustic models (Delany–Bazley–Miki, rigid-frame, and limp-frame models). Nonwoven sheets with fiber diameters in the micrometer and nanometer ranges were prepared by electrospinning from sol-gel precursors. All the silica fiber sheets showed a superior sound absorption coefficient over glass wool. Our theoretical analyses clearly indicate that the sound absorption mechanism of the thin fiber sheets gradually approaches midway between porous-type and panel-type from typical porous-type with decreasing fiber diameter. In addition, the effect of the flow resistivity due to the friction between the air and the fiber, as well as the effect of sample vibration induced by the sound waves, is more substantial for fibers thinner than 3 μm. The insights provided by our quantitative analysis will be useful for the rational design of high-performance porous thin-film sound absorbers.