A cell structure for use in an acoustic panel, the cell structure comprising: a first cavity having a regular shape cross section perpendicular to a central axis, the first cavity having a continuous first boundary wall , the first cavity having a floor side , a cell height , and an entrance side defined by a first incircle, the floor side covered by a cell structure floor; a second cavity disposed coaxially within the first cavity, the second cavity having the regular shape cross section perpendicular to the central axis, the second cavity having a continuous second boundary wall , the second cavity having a floor side covered by the cell structure floor, the cell height, and an entrance side defined by a second incircle; characterized by a first number of inner chambers disposed within the second cavity from the second cavity entrance side to the cell structure floor, each of the inner chambers having an equal inner chamber cross sectional area created by radially dividing the second incircle, the inner chambers being rotated in a first direction around the central axis by at least p rotations per 2.5 cm (per inch) from the second cavity entrance side to the cell structure floor; and a second number of outer chambers disposed in a volume between the continuous first boundary wall and the continuous second boundary wall , from the first cavity entrance side to the cell structure floor, each of the outer chambers having an equal outer chamber cross sectional area created by radially dividing the first incircle into equally sized outer sections, the outer chambers being rotated around the central axis in an opposing direction to the first direction by the at least p rotations per 2.5 cm (per inch) from the first cavity entrance side to the cell structure floor; a partition dividing an outer chamber into two modified outer chambers; and a port opening from the divided outer chamber into the inner cavity, the port opening positioned near the partition. a first cavity having a regular shape cross section perpendicular to a central axis, the first cavity having a continuous first boundary wall , the first cavity having a floor side , a cell height , and an entrance side defined by a first incircle, the floor side covered by a cell structure floor; a second cavity disposed coaxially within the first cavity, the second cavity having the regular shape cross section perpendicular to the central axis, the second cavity having a continuous second boundary wall , the second cavity having a floor side covered by the cell structure floor, the cell height, and an entrance side defined by a second incircle; a first number of inner chambers disposed within the second cavity from the second cavity entrance side to the cell structure floor, each of the inner chambers having an equal inner chamber cross sectional area created by radially dividing the second incircle, the inner chambers being rotated in a first direction around the central axis by at least p rotations per 2.5 cm (per inch) from the second cavity entrance side to the cell structure floor; and a second number of outer chambers disposed in a volume between the continuous first boundary wall and the continuous second boundary wall , from the first cavity entrance side to the cell structure floor, each of the outer chambers having an equal outer chamber cross sectional area created by radially dividing the first incircle into equally sized outer sections, the outer chambers being rotated around the central axis in an opposing direction to the first direction by the at least p rotations per 2.5 cm (per inch) from the first cavity entrance side to the cell structure floor; a partition dividing an outer chamber into two modified outer chambers; and a port opening from the divided outer chamber into the inner cavity, the port opening positioned near the partition. <EOS>