Patent ID: 8863893

Claim:
An aircraft engine nacelle inlet comprising: an acoustic barrel panel having an outer surface, an inner surface, a forward end, and an aft end; a septum sandwiched or buried within the acoustic barrel panel, wherein the septum has a plurality of holes formed therein of varying dimensional areas and/or varying proximities relative to each other; and a face sheet bonded to the inner surface of the acoustic barrel panel, spaced a distance apart from the septum, and having a plurality of holes formed therein of varying dimensional areas and/or varying proximities relative to each other, wherein acoustical impedance of at least one of the face sheet and the septum is incrementally increased in a direction from the aft end toward the forward end of the acoustic barrel panel by at least one of incrementally decreasing the dimensional areas of the holes and incrementally increasing the proximities of the holes relative to each other.