Abstract: The invention relates to a sound recording device for a public address system. Sound is emitted from a sound source, picked up by at least two sound sensors and converted into electrical signals. The sound sensors are located at a distance from a reference position which corresponds to an ideal set position. Directional vectors located between said reference position and the sound sensors indicate different directions. The sound sensors are electrically or acoustically connected to a common signal amplitude add device.

Abstract: A fixing member (1) designed for at least partially interlocking axial securement in a solid body (4) by means of an initially fluid setting material (2) introduced into a blind borehole (3), and is intermediately mechanically fixed and adjustable. The fixing member (1) is a peripherally closed medium to thickwalled tubular member (5), at least in part radially deformed and of uniform wall thickness having an axial passageway (6) extending through it.

Abstract: A sound-absorbing cellular component is produced in multiple-chamber array, using a grid of spaced elongate rods, and by engaging to the rods of said grid a foil of deformable sheet material which is then drawn by deformation through spaces between rods, to thereby define adjacent partition walls of adjacent chambers. Various embodiments are described, involving retention and/or removal of the rods, and/or involving application of one or more insulating or finishing materials continuously over outwardly facing bottoms of the chambers of the array.