| 摘要 |
A noise reduction system for a jet engine including a tubular exhaust shroud affixed to the engine through which engine exhaust gases pass, porous acoustical lining affixed to a substantial portion of the internal circumferential surface of the shroud, a chamber in contact with the acoustical lining outer surface and a controllable source of air pressure affixed to the chamber to control the passage of air through the acoustical lining to thereby vary the acoustical absorption properties of the lining.
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