| 摘要 |
PROBLEM TO BE SOLVED: To prevent notification sounds and notification messages at night from becoming noise to neighboring houses. SOLUTION: If an ambient illuminance is higher than a prescribed threshold, a control unit 20 judges based on a detection signal of a detector 28 that it is the daytime and discriminates that it is the night-time if it is lower than the prescribed threshold. If it is discriminated as being night-time, a common space apparatus (lobby interphone 2) lowers an amplification degree of a variable amplifier A2 down to a lower value than the value, when it is discriminated as being daytime. The informing sound and the informing message at night are prevented from becoming the noise to the neighboring houses, as a sound volume of the informing sound and the informing message, accompanied with an operation of number keys or the like, is lowered at night as compared with the sound volume during daytime. COPYRIGHT: (C)2006,JPO&NCIPI
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