Sound wave guide for use in acoustic structures

摘要

The bandwidth or acoustical range of an acoustic structure is increased by locating a sound wave guide within the acoustic cell. The wave guide divides the cell into two acoustical chambers. The two chambers provide an effective increase in resonator length of the cell.

主权项

1. An acoustic structure for reducing noise generated from a source, said acoustic structure comprising:
a honeycomb comprising a first edge to be located closest to said source and a second edge, said honeycomb comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls; an acoustic barrier located at the second edge of said honeycomb or within at least one of said cells to form an acoustic resonator wherein the depth of said acoustic resonator is equal to the distance between the first edge of said honeycomb and said acoustic barrier; a frusto-conical duct located in said acoustic resonator, said frusto-conical duct comprising a sound permeable wall having interior and exterior surfaces, said sound permeable wall comprising an inlet edge defining a duct inlet and outlet edge defining a duct outlet wherein said duct inlet is closer to said honeycomb first edge than said duct outlet and wherein said sound permeable wall is an open mesh fabric or a perforated plastic film.