Sound propagation in fibrous absorbing materials with glue effect

Abstract:

Two equivalent formulations for the effective density and the effective bulk modulus of fibrous materials were derived from the microscopic scattering process of the filaments according statistical consideration by Zhao Songling. Then there are some difference between its theoretical results and experimental data. This difference will increase with sound frequency increases. Its cause maybe lay in the glue effect. Considering glue effect and introducing definition of equivalent volume mass, the improvement equivalent formulations were proposed, and an experimental examination is discussed also. Theoretical results are in better agreement with the experimental data. The effects of glue, volume mass, fibrous radius and thickness on acoustic properties were discussed using the improvement equivalent formulations. The analytic results are perfectly agreement with the conclusion from a large number of measurement data on acoustic properties of fibrous absorbing materials.