Abstract: A method of manufacturing a double-structure sound absorbing wall having a cavity defined by joining first and second plate members, comprising the steps of providing said first and second plate members with gas bleeding holes and recesses depressed toward the inside of said cavity to abut the members to each other, providing a sound insulating member foamable by heat received in said cavity with relief holes for spot-welding corresponding to said cavity, holding said sound insulating member by said recesses upon abutting of said plate members, abutting said peripheral edges to each other, spot-welding said recesses to each other to close said cavity, and foaming said sound insulating member by heating to fill said cavity therewith.

Abstract: A shift-time indicating system for a manually operated transmission comprising two actuating circuits for shift-up and shift-down indicators, said circuits being arranged in parallel through change-over switches. The switches are operated in response to positions of a shift lever of the transmission and to an intake negative pressure of an engine. Each indicator is actuated when both of the switches are connected to the corresponding circuit, thereby indicating the driver a necessity of shift-up or shift-down.