A method of producing an acoustic panel suitable for performing acoustic control of jet engine noise, the method comprising the steps of: - conforming a sheet of thermoplastic paper into rows that each comprise a three dimensional shape, - transforming the sheet into a multi-celled core by: - identifying fold lines separating the rows, - folding the sheet at the fold lines in a pleat fold, thereby uniting upper surfaces of adjacent rows and uniting lower surfaces of adjacent rows in the sheet , and - compressing the rows of the folded sheet together in the presence of heat causing adjacent rows to fuse together into hexagonal cells , each cell including a double wall defining a single side, - heating core and pressing double walls resulting in double walls plastically deforming and integrating into each other to create core as a singly integral shape comprising unified, seamless walls of thermoplastic material, - applying a backing sheet to the core ; - applying a facesheet to a surface of the core that includes openings able to direct a portion of airflow across the facesheet into the cells , preferably wherein the facesheet comprises a thermoplastic material; and wherein applying the facesheet comprises: ∼ fusing the facesheet to the surface via the application of heat and pressure, - and the method preferably further comprising the step of inserting a septum into each of the cells . - conforming a sheet of thermoplastic paper into rows that each comprise a three dimensional shape, - transforming the sheet into a multi-celled core by: - identifying fold lines separating the rows, - folding the sheet at the fold lines in a pleat fold, thereby uniting upper surfaces of adjacent rows and uniting lower surfaces of adjacent rows in the sheet , and - compressing the rows of the folded sheet together in the presence of heat causing adjacent rows to fuse together into hexagonal cells , each cell including a double wall defining a single side, - heating core and pressing double walls resulting in double walls plastically deforming and integrating into each other to create core as a singly integral shape comprising unified, seamless walls of thermoplastic material, - applying a backing sheet to the core ; - applying a facesheet to a surface of the core that includes openings able to direct a portion of airflow across the facesheet into the cells , preferably wherein the facesheet comprises a thermoplastic material; and wherein applying the facesheet comprises: ∼ fusing the facesheet to the surface via the application of heat and pressure, - identifying fold lines separating the rows, - folding the sheet at the fold lines in a pleat fold, thereby uniting upper surfaces of adjacent rows and uniting lower surfaces of adjacent rows in the sheet , and - compressing the rows of the folded sheet together in the presence of heat causing adjacent rows to fuse together into hexagonal cells , each cell including a double wall defining a single side, - heating core and pressing double walls resulting in double walls plastically deforming and integrating into each other to create core as a singly integral shape comprising unified, seamless walls of thermoplastic material, - applying a backing sheet to the core ; - applying a facesheet to a surface of the core that includes openings able to direct a portion of airflow across the facesheet into the cells , preferably wherein the facesheet comprises a thermoplastic material; and wherein applying the facesheet comprises: ∼ fusing the facesheet to the surface via the application of heat and pressure, - and the method preferably further comprising the step of inserting a septum into each of the cells . <EOS>