This paper describes designs of structures and control systems of an active sound insulation unit consisting of active cells which are individually controlled as a single input single output system. Two types of Active Sound Insulation Cell (ASIC) using lightweight card-type speakers were manufactured for trial. It became clear that ASIC can reduce the transmitted noise whose sound field inside the cell is uniform. That means that the size of ASIC should be less than quarter wavelength of controlled sound and secondary noise sources should be properly arranged. The feedback control system for ANC was systematically designed by Hinfinity control theory, and the sound attenuating performance was verified by the simulation.

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