| 摘要 |
A device that allows the evaluation of the acoustical Biot-Allard material parameters in a fast and efficient way by using an inverse hybrid calculating tool. The calculating tool is called "inverse", since the material parameters are calculated backwards, i.e. by starting from standard transfer functions measured between microphone positions placed above and below a sample of the material inserted into a cylindrical tube and by using theoretical formulas based on material models. It is at the same time called "hybrid", since not all the parameters are actually calculated backwards but instead a limited number of them (the porosity and possibly the air flow resistivity) is measured with classical direct methods and in advance. The principle of the invention is based on the measurement of transfer functions instead of impedances, it is able to minimize the number of measurements necessary for the evaluation of the material parameters of interest and it exploits also a more robust experimental setup. |
