| 摘要 |
PROBLEM TO BE SOLVED: To efficiently improve conversation articulation in a cabin by reducing noise level in a frequency band of a human conversation, specially, a high-frequency range. SOLUTION: A soundproof layer 202 is 5 to 50 mm thick and≤2,000 g/m<SP>2</SP>in weight per unit area, and the soundproof layer 202 comprises two layers differing in density, i.e. a high-density soundproof layer 202a and a low-density soundproof layer 202b. The high-density soundproof layer 202a bonded to an air-permeable resonance layer 203 through a bonding layer 204 is 0.05 to 0.20 g/cm<SP>3</SP>in density and 2 to 30 mm in thickness, and the low-density soundproof layer 202b, on the other hand, is bonded to the opposite surface of the high-density soundproof layer 202a from the air-permeable resonance layer 203 through a bonding layer 202c while the density is 0.01 to 0.10 g/cm<SP>3</SP>and the thickness is 2 to 30 mm. COPYRIGHT: (C)2005,JPO&NCIPI
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