Predictive model of sound propagation in porous materials: Extension of applicability in Kato model

In a previous paper, it was shown that the Kato model, with the material density and fiber diameter, can be used as a predictive model that enables the acoustic design (optimization of the fiber mixing rate) of fibrous materials. However, it does not have sufficient analytical precision for a material with high-bulk-density, so the model has limited applicability. Also, since the material density and fiber diameter are required as parameters, the Kato model cannot be applied to fibrous materials or foamed materials, the parameters of which are unknown. To solve these problems, in this paper, a technique of applying the Kato model to fibrous materials with high-bulk-density, fibrous materials with unknown material density and fiber diameter, and foamed materials is shown to extend its application.