Sound absorber, sound absorbing panel and sound absorbing wall

A sound absorber comprising a plurality of cavities different in at least one of shape and size, wherein

• a wall of a first cavity included in the plurality of cavities includes a first region and a second region, wherein a plurality of through-holes connecting an interior of the first cavity to an exterior of the first cavity is formed in the first region, and wherein no through-holes connecting the interior of the first cavity and the exterior of the first cavity is formed in the second region adjacent to the first region,
• a wall of a second cavity included in the plurality of cavities includes a third region and a fourth region, wherein a plurality of through-holes connecting an interior of the second cavity to an exterior of the second cavity is formed in the third region, and wherein no through-holes connecting the interior of the second cavity and the exterior of the second cavity is formed in the fourth region adjacent to the third region, and
• density of through-holes in the first region is different from density of through-holes in the third region.

A sound absorber comprising a plurality of cavities mutually different in at least one of shape and size, wherein

• a wall of a first cavity included in the plurality of cavities includes a first region and a second region, wherein a plurality of through-holes connecting an interior of the first cavity to an exterior of the first cavity is formed in the first region, and wherein no through-holes connecting the interior of the first cavity and the exterior of the first cavity is formed in the second region adjacent to the first region,
• a wall of a second cavity included in the plurality of cavities includes a third region and a fourth region, wherein a plurality of through-holes connecting an interior of the second cavity to an exterior of the second cavity is formed in the third region, and wherein no through-holes connecting the interior of the second cavity and the exterior of the second cavity is formed in the fourth region adjacent to the third region, and
• a number of through-holes in the first region is different from a number of through-holes in the third region.