ACOUSTIC TECHNOLOGY FOR ROOMS, SUCH AS CONCERT HALLS, THAT CAN BE VARIED BETWEEN A SOUND-ABSORPTIVE AND A SOUND REFLECTIVE STATE

The present invention relates to a panel for attachment to boundaries of a room, such as a concert hall, the panel comprising a panel board (1, 28) provided with through openings (2, 29) between a first surface (1', 28') and a second surface (1'', 28'') of the panel board (1, 28); a closing unit (3, 14, 30) provided opposite to and facing the second surface (1'', 28'') of the panel board (1, 28), such that the distance between the second surface (1'', 28'') of the panel board (1, 28) and the closing unit (3, 14, 30) can be varied between a closed state, in which the closing unit (3, 14, 30) closes the through openings (2, 29) in the panel board (1, 28) and an open state, in which the closing unit (3, 14, 30) does not close the through openings (2, 29) in the panel board; where the closing unit (3, 14, 30) in first regions (15, 32) of the closing unit that in the closed state of the panel cover the through openings (2, 29) in the panel board (1, 28) is substantively sound impenetrable, so that sound is substantively prevented from being transmitted through the through openings (2, 29) in the panel board (1, 28) in the closed state 15 of the panel; and the closing unit (3, 14, 30) in one or more second regions (4, 12, 13, 17, 37, 38) of the closing unit (3, 14, 30) that in the closed state of of the panel are not totally or partly coinciding with said through openings (2, 29) in the panel board (1, 28) allow transmission of sound through the closing unit. The invention further relates to a device comprising a panel of the invention and a system of such devices