PURPOSE: To shorten the time period, which is required for check during an inspecting step, thereby to make it possible to accomplish the confirmation for a short time peirod by making it possible to fast forward the content of a time circuit for measuring the temporary stop time of alarm sounds.

CONSTITUTION: In case alarm sounds are stopped for a while, a switch S4 is turned on to close a gate circuit G9 so that the alarm sounds are stopped and so that the temporary stop time is measured by stepwise forwading the content of a shift register C2 thereby to generate the alarm sounds a preset time later. In case the temporary stopping function is checked during an inspecting step, the content of a shift register C2 can be fast forwarded so that the function is instantly confirmed.