An acoustical panel has a multiplicity of short micro-slits, about 10 mm in length each, with each micro-slit having a wedge shaped cross-section in which the opening on the front side of the panel is wider than the opening on the rear side of the panel by a factor of about 2 to effectively absorb sound frequencies in the range of 250-2000 Hz, with the micro-slits greater than 4%. The micro-slits are spaced apart less than 5 mm and several different patterns of micro-slits may be employed including micro-slits that are straight as well as arcuate or some combination of straight and arcuate. The area of the micro-slits on the front surface of the panel exceeds 4%.

A noise reduction apparatus can include a frame and multiple spaced apart panels positioned adjacent to each other. Each of the panels or only one of the spaced apart panel elements may have holes therein to receive acoustic waves for absorbing the waves between the panels. The panels can be attached to a frame or other connection structure so that the arrangement of panels can be hung over a work space or positioned in a work space (e.g. in a wall, formed as a partition or wall, included as part of shelving, etc.). The panels can also be incorporated into a light fixture that may hang from a ceiling or be attached to some other type of support (e.g. a table, a base, etc.). The panels can be composed of glass, wood, or other type of material.

The invention concerns a reinforced concrete element comprising an at least partially open-cell foamed, sound-absorbing material which is partially exposed on a surface of the concrete element. The surface on which the foamed material is exposed consists only partially of the foamed material and the reinforcement is partially surrounded by the foamed material. The invention further concerns a method of producing the concrete element and the use thereof as an acoustic ceiling in a building.

An acoustical panel has a multiplicity of short micro-slits, about 10 mm in length each, with each micro-slit having a wedge shaped cross-section in which the opening on the front side of the panel is wider than the opening on the rear side of the panel by a factor of about 2 to effectively absorb sound frequencies in the range of 250-2000 Hz, with the micro-slits greater than 4%. The micro-slits are spaced apart less than 5 mm and several different patterns of micro-slits may be employed including micro-slits that are straight as well as arcuate or some combination of straight and arcuate. The area of the micro-slits on the front surface of the panel exceeds 4%.

The invention relates to a drywall construction for resonance sound absorption. The drywall construction comprises a plurality of drywall profiles and fixed thereto at least one layer of plasterboards having an opening arranged therein. The drywall construction further comprises a resonance chamber in fluid connection with the opening, the resonance chamber and the opening having a size and shape so that sound of predetermined resonance frequencies enters the resonance chamber via the opening.

Disclosed herein is a sound insulation panel which is easy to manufacture and has a light weight. The sound insulation panel includes: a patterned plate comprising an edge plate and a separation plate extending into an inner region of the edge plate and dividing the inner region into a first elastic region and a second elastic region; and an elastic plate protruding from the patterned plate to be stepped with respect to the patterned plate and including a first elastic plate disposed in the first elastic region and a second elastic plate disposed in the second elastic region, the elastic plate blocking an air flow path and converting airborne sound waves into elastic waves, wherein the first elastic plate and the second elastic plate are displaced in opposite directions at a resonant frequency of the sound insulation panel.