Abstract: For reproducing sound in a rectangular room in association with a video playback screen (10), from audio signals of the kind comprising at least three main channels (2, 3, 4) and a bass effects channel (1), at least five loudspeakers (11, 12, 13, 14, 15) are used that are specialized for reproducing audio frequencies lower than 120 Hz, four of which (11, 13, 14, 15) are arranged in four respective corners of the room and at least one of them (12) is arranged in the proximity of the screen. The two loudspeakers (14, 15) arranged in the corners furthest away from the screen receive either a signal constituted by the sum of the signals for the other loudspeakers with polarity inversion, with individual delays, and with lowpass filtering, or else a signal coming from a microphone (23, 25) arranged in the immediate proximity of each of the two loudspeakers (14, 15) concerned, the microphone signal being inverted in polarity and lowpass filtered.

Abstract: A projection screen comprises a film having a projection side and provided with a number of passages adapted for permitting emitted sound waves to pass through said film. The projection screen is characterized in that these passages are arranged in such a manner that, if alignments can be detected, at least the principal ones have an angle that is not zero with regard to the vertical and horizontal edges of the screen.

Abstract: The front projection screen comprises firstly a support layer of substantially black color suitable for rolling onto a roll-up tube, and a weight at its bottom edge, and secondly a projection surface that is substantially white or pale gray, being smaller in size than said support layer, and being fastened to the support layer via a junction at its top edge and overlying the face of the screen that is to receive projection.

Abstract: A projection screen comprises a film having a projection side and provided with a number of passages adapted for permitting emitted sound waves to pass through said film. The projection screen is characterized in that these passages are arranged in such a manner that, if alignments can be detected, at least the principal ones have an angle that is not zero with regard to the vertical and horizontal edges of the screen.

Abstract: The front projection screen comprises firstly a support layer of substantially black color suitable for rolling onto a roll-up tube, and a weight at its bottom edge, and secondly a projection surface that is substantially white or pale gray, being smaller in size than said support layer, and being fastened to the support layer via a junction at its top edge and overlying the face of the screen that is to receive projection.