| 摘要 |
A liner assembly for a duct includes noise attenuation panel for dissipating sound energy generated within the duct. A damage resistant acoustic panel for installation in high velocity impact prone locations includes a plurality of openings for communicating noise signals to the noise attenuation panel. At lease some of the openings includes a first diameter that extends a depth into the acoustic panel. The depth is no greater than the first diameter. A second portion extends the remainder of the thickness into the acoustic panel and includes a diameter greater than the first diameter. The increased area provided by the second diameter reduces restriction to the transmission of sound energy to the noise attenuation panel within an acoustic panel thickness required for protecting against foreign object damage.
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