Abstract: An acoustic loudspeaker is mounted within a curved reflecting enclosure. Openings through the enclosure allow sound vibrations from the front of the speaker to emerge from the enclosure. A port in the enclosure, spaced away from the openings allow vibrations from the rear of the speaker to emerge from the enclosure. The inside of the enclosure is shaped to direct the desired vibrations through the port. A second embodiment has two speakers and two ports non-interferingly mounted in a single reflecting enclosure.

Abstract: Rooms of a building are provided with an air distributing ceiling and plenum chambers thereabove. Treated air is pumped to the plenum chambers where it passes through the ventilating ceiling to heat or cool an enclosed area below. A recirculation system permits withdrawal of all of the treated air from the enclosed area. The withdrawn air is recirculated after mixing with freshly treated air. The air is treated by passing a portion thereof over a heating or cooling coil while the remainder bypasses the coil. The mixture of treated and bypass air is pumped at a high rate into the plenum chambers where a static pressure such as 1 inch of water exists.