Abstract: An acoustic attenuation device includes resonator panels stacked in a thickness direction of the device. Each resonator panel is tuned to a different frequency range and includes a plurality of openings through which excited air resonates. The resonator panels are placed adjacent to other resonator panels such that all openings are accessible to the environment.

Abstract: An acoustic attenuation assembly includes a low frequency sound attenuation device having at least one sound attenuation chamber containing a volume and mass of air. First and second openings are associated with each low frequency chamber through which excited air resonates. The first and second openings extend through the first sheet into each low frequency chamber. Each chamber has an open side. A high frequency sound attenuation device is secured to the low frequency attenuation device and closes the open side of each chamber. The high frequency sound attenuation device includes a plurality of projections formed from a sound absorbing material that absorbs excited air.

Abstract: An acoustic attenuation device includes resonator panels stacked in a thickness direction of the device. Each resonator panel is tuned to a different frequency range and includes a plurality of openings through which excited air resonates. The resonator panels are placed adjacent to other resonator panels such that all openings are accessible to the environment.

Abstract: An acoustic attenuation assembly includes a low frequency sound attenuation device having at least one sound attenuation chamber containing a volume and mass of air. First and second openings are associated with each low frequency chamber through which excited air resonates. The first and second openings extend through the first sheet into each low frequency chamber. Each chamber has an open side. A high frequency sound attenuation device is secured to the low frequency attenuation device and closes the open side of each chamber. The high frequency sound attenuation device includes a plurality of projections formed from a sound absorbing material that absorbs excited air.

Abstract: A method of manufacturing an acoustic attenuation device includes three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define attenuation chambers. Each chamber has at least one opening through which excited air resonates.

Abstract: A method of manufacturing an acoustic attenuation device includes three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define attenuation chambers. Each chamber has at least one opening through which excited air resonates.

Abstract: A method of forming a composite structure can include providing a plurality of composite panels of material, each composite panel having a plurality of holes extending through the panel. An adhesive layer is applied to each composite panel and a adjoining layer is applied over the adhesive layer. The method also includes stitching the composite panels, adhesive layer, and adjoining layer together by passing a length of a flexible connecting element into the plurality of holes in the composite panels of material. At least the adhesive layer is cured to bond the composite panels together and thereby form the composite structure.

Abstract: A method of forming a composite structure can include providing a plurality of composite panels of material, each composite panel having a plurality of holes extending through the panel. An adhesive layer is applied to each composite panel and a adjoining layer is applied over the adhesive layer. The method also includes stitching the composite panels, adhesive layer, and adjoining layer together by passing a length of a flexible connecting element into the plurality of holes in the composite panels of material. At least the adhesive layer is cured to bond the composite panels together and thereby form the composite structure.