抄録
In the design of the cabin such as a car and an agricultural machine, the construction machine, it is necessary to consider about the acoustic feature in the cabin, and to design it. However, I hear that it is possible only to the frequency range of approximately 0-300Hz by the analysis using FEM. On the other hand, the frequency range of 300-1000Hz, called ‘middle frequency range’ is regarded as important about the design of the cabin, but the analytical technique of this range is nonestablishment. Therefore we perform a study to suggest the new analytical technique of this middle frequency range. In this study, we suggest the analytical technique of the acoustic absorption sound field using the mode distortion energy method as the first stage of analyzing a cabin. By this technique, we demand the energy of the air domain and the energy of the sound absorption material domain from the model that sound absorption material was added to on the wall of the cuboid space each and derive the same loss coefficient by the ratio of energy used by energy and sound absorption material of the whole space. At first we compare the truth level by the theory analysis with the solution of the same acoustic absorption sound field by the suggestion technique in simulation and confirm the validity of the suggestion technique. Then, we compare it with the experimental value in the model who stuck sound absorption material on the wall entire surface and the model that stuck sound absorption material on a part of the wall and confirm the validity of the suggestion technique experimentally. Finally we perform a comparison between suggestion technique and classic technique using A and show the thing that is more correct than classic technique.
