Abstract: A valve assembly for a plate-type flow-control valve has a stationary plate having a planar upper face and formed with at least one inlet port and with an outlet port opening offset therefrom on the upper face and a movable plate having a planar lower face slidable on the upper face of the stationary plate and formed with a pocket open at the face and defined by a generally flat floor having an outer periphery and an annular side wall extending from the periphery to the faces. An annular screen in the pocket has an inner wall inward of the side wall and itself having a lower edge spaced slightly above the faces and an end wall extending outward from the lower edge to the side wall generally at the faces. This screen defines with the side wall and outer periphery of the floor an annular chamber extending in the pocket around the outer floor periphery.

Abstract: Disclosed herein is a sound diffusion plant with very low directivity. The plant, normally of the multiway type, is essentially characterized by the fact that each way comprises a pair of loudspeakers arranged one opposite the other, the diaphragms of which are enclosed in a space delimitated by screening elements made of high acoustic absorption material.The said plant enables the sound diffusion to be uniform in the surrounding space and makes it possible to limit greatly undesired effects, such as for example, sound "haloes" and identical sounds reproduced by different ways being out of phase.