Abstract: A sound absorber arrangement includes a plurality of sound absorbing layers of porous materials such as glass wool, rock fiber or cellular plastic, and high-polymer films, are alternately laminated in a direction perpendicular to a sound incidence plane. The layer thicknesses are increased in order in a direction away from the sound incidence plane. The sound absorber arrangement makes it possible to make a sound absorbing coefficient constant over the low to high frequency sound range.

Abstract: In a packet communication method, a packet communication device, an input transmission frame of V (bytes/sec) consisting of a transmission overhead of V.sub.OH (bytes/sec) containing control information for transmission and a pay load of V.sub.p (bytes/sec) of c (=a+b) bytes, the outer cell consisting of an information field of a b-byte length containing transmission data and a header field of an a-byte length containing a first control information for transmitting the information field. The transmission overhead is removed from and a second control information is added to the input transmission frame. The input transmission frame with the second control information and without the transmission overhead is converted to a plurality of inner cell trains of f (=b+j) bytes length, the inner cell trains consisting of an information field of a b-byte containing the transmission data and a second header field of j (=a+d) bytes consisting of the first control information and the second control information (where f.

Abstract: A packet switching equipment housing therein a plurality of pairs of an input line and an output line is provided with a monitor circuit for monitoring a packet congestion state in the packet switching equipment for each output line. When a packet congestion is detected in association with either one of the output lines, a congestion indicator is added to a packet to be delivered to the output line so as to return the packet as a congestion notice packet to an equipment as the transmission source of the packet; furthermore, the input packet is relayed via the output line to the destination equipment.

Abstract: A telephone exchange system has a plurality of bit synchronization circuit each provided for an individual subscriber's line. A single clock generating circuit which generates a plurality of clocks is provided in common to the plurality of bit synchronization circuits. The bit synchronization circuit selects one clock of a phase suitable for regenerating an input data signal among the plurality of clocks applied thereto by the clock generating circuit, and regenerates and phases the input data signal by using the selected clock.

Abstract: In the ATM switching system, an ATM speech path is divided into a plurality of functional blocks. A routing function for distributing cells (packets) each of a fixed length to addresses outgoing lines and a logical multiplexing function are imparted to a switch, while other functions associated with a line typified by a phase synchronizing function and a flow control function are incorporated en bloc in ATM line terminating units and functions capable of being processed by hardware in common to the lines are assembled in a line common unit. The ATM line terminating unit physically terminates transmission lines and performs the processing relevant to header information of the cells each of a fixed length (ATM terminating processing) and includes a cell phase synchronizing circuit for matching the temporal positions of the cells among the lines and a flow control circuit for avoiding overload exceeding the load declared by subscriber terminal.