| 摘要 |
PROBLEM TO BE SOLVED: To provide a sound absorbing device which includes the compatibility to make the device compatible to various operating conditions, is relatively low in a manufacturing cost and has excellent durability and a sound absorbing method which is capable of lowering a noise level in various operating states. SOLUTION: The sound absorbing device 10 has housings 11 and the housings delineate sound absorbing spaces 12. Openings 13 formed at the housings 11 communicate the sound absorbing spaces 12 and flow passages 20, thereby decreasing the sounds in the flow passages 20. The resonance frequencies and impedance of the sound absorbing spaces 12 are made variable, by which the sound absorbing device 10 is made compatible to the operating conditions meeting the sound field in the flow passages 20. The device has elastic films 15 for changing the volume of the sound absorbing spaces 12 as mechanical means for attaining the compatibility and has heating wires 14 and heating wire nets 17 as thermal means for attaining the compatibility. The sound absorbing method consists in changing the resonance frequencies and impedance of the sound absorbing spaces 12 by the thermal means and/or the mechanical means so as to make the sound absorbing device 10 compatible to the sound field in the flow passages 20.
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