Abstract: A transducer arrangement for active noise cancellation signals provides an acoustically permeable membrane between ports in direct communication with the noise propagating conduit and the transducers delivering sound pulses to the port. A housing defines at least one chamber exposed to at least one face of a transducer diaphragm, and each chamber is connected in fluid communication with the conduit through at least one port. The chamber is partitioned by the membrane to include chamber portions with a predetermined volumetric relationship. In a preferred embodiment where the transducer arrangement is coupled to a motor vehicle exhaust conduit, the membrane is preferably a silicone impregnated polyurethane film reinforced with aromatic polyamide fibers. Such a member provides a waterproof, acoustically permeable partition between the port and any adjacent speaker face that can withstand high temperatures.

Abstract: The invention relates to a loudspeaker arrangement for creating a three-dimensional stereo sound effect. The loudspeaker arrangement is to be located at a suitable distance from sound-reflecting surfaces. The loudspeaker elements (12a, 13a, 14a; 12b13b, 14b) of the left-hand channel (2) and the right-hand channel (3) in the loudspeaker arrangement are located within one and the same loudspeaker unit (1), where they are separated from each other by means of a zone (4) which is at least of the same size as the interval (a) between human ears. The loudspeaker elements are arranged to radiate towards different sides (A, B) of the said zone (4), in a similar fashion, within 180.degree. circle sectors, in which case the sounds reflected from the surfaces, together with the sounds coming directly from the loudspeaker unit, create a depthwise expanded, three-dimensional stereo sound effect, mainly within the sector (10) expanding away from the loudspeaker unit.

Abstract: A muffler assembly of an internal combustion engine comprises an inner casing in which is defined a first expansion chamber into which is inserted one end of the exhaust pipe having another end connected to an exhaust gas port of the engine, an outer casing disposed outside the inner casing so as to define second and third expansion chambers between the inner and outer casings, a first baffle pipe disposed so as to mutually communicate the first and second expansion chambers, a second baffle pipe disposed so as to mutually communicate the second and third expansion chambers, and a tail pipe member disposed so as to communicate the third expansion chamber and the outside of the outer casing. The inner and outer casings are formed by two plate members, respectively, which are secured together when the muffler assembly is assembled. A sound absorption chamber is formed around the outer periphery of the tail pipe.

Abstract: An imaging system which uses a right-to-left scanning operation is enabled by first detecting by an optical sensor the right hand edge of a document to be copied, the left edge of the document being registered at the left edge of the platen. The scanning operation is initiated at the detected right hand edge and proceeds to the left. The end of scan coincides with the left registration edge. Book copying is enabled by adding a sloping left edge to the platen placing the book to be copied over the edge corner. The optical system is rotated for a book copy mode so that light penetrating the binding area is transmitted along the optical path. This arrangement allows required pre-scan excursion to take place in the space to the right of the start of scan position, thus avoiding interference with the sloping book edge.