Abstract: A multiple loudspeaker deviceQ) comprising a frame (3) with a first loudspeaker (5) for reproducing sound in a higher frequency range and a second loudspeaker (7) for reproducing sound in a lower frequency range, the frequency ranges having a crossover frequency fc. The first loud-speaker has a first radiation surface (5a) of maximal 1000 m2 and the second loudspeaker has a second radiation surface (7a), a central area (5b) of the first radiation surface and a central area (7b) of the second radiation surface being situated at a vertical distance d from each other. In order to obtain sound of high quality the parameters fc and d have the following values: 750 Hz<fc<3000 Hz, d>2. ?Jfc, (?J?c is the wavelength of the reproduced sound at fc), and 750 mm<d<3000 mm.

Abstract: A panel-shaped loudspeaker includes a panel (1) and an exciter coupled to the panel. The panel is provided with two parallel extending thin walls (1a, 1b) which are interconnected by a structure of thin strip-shaped partitions (1c) situated between the walls. The longitudinal axes of all partitions extend parallel to each other and give the panel an anisotropic bending stiffness. The material of the walls and the partitions of the panel has an internal damping which is at least 2.5% of the critical damping of the relevant material, used in the panel.

Abstract: Panel-shaped loudspeaker comprising a panel (1) and an exciter coupled to the panel. The panel is provided with two parallel extending thin walls (1a, 1b) which are interconnected by means of a structure of thin strip-shaped partitions (1c) situated between the walls. The longitudinal axes of all partitions extend parallel to each other and give the panel an anisotropic bending stiffness. The material of the walls and the partitions, used in the panel, has an internal damping which is at least 2.5% of the critical damping of the relevant material, used in the panel.